0001021635-21-000026 | 10-K | XBRL Viewer

462.8

491.8

474.6

391.3

355.0

321.6

101.4

93.6

92.0

Operating expenses

955.5

940.4

888.2

Equity in earnings (losses) of unconsolidated affiliates

522.2

504.3

489.6

OTHER INCOME (EXPENSE)

^[1]

(668.0)

^[2]

113.9

152.8

Allowance for equity funds used during construction

4.8

4.5

23.8

Pension and Other Postretirement Benefits Cost (Reversal of Cost)

(3.9)

(9.8)

(10.8)

Other income

37.5

21.9

21.7

Other expense

(35.2)

(23.5)

(23.4)

Net other income (expense)

(664.8)

107.0

164.1

INTEREST EXPENSE

Interest on long-term debt

152.8

138.3

157.4

Allowance for borrowed funds used during construction

(1.9)

(2.8)

(11.7)

Interest on short-term debt and other interest charges

7.6

12.4

10.3

INCOME (LOSS) BEFORE TAXES

158.5

147.9

156.0

(301.1)

463.4

497.7

INCOME TAX EXPENSE (BENEFIT)

(127.4)

29.8

72.2

BASIC AVERAGE COMMON SHARES OUTSTANDING

$ (173.7)

$ 433.6

$ 425.5

200.1

199.7

DILUTED AVERAGE COMMON SHARES OUTSTANDING

200.1

200.7

200.5

BASIC EARNINGS (LOSS) PER AVERAGE COMMON SHARE

$ (0.87)

$ 2.17

$ 2.13

DILUTED EARNINGS (LOSS) PER AVERAGE COMMON SHARE

(0.87)

2.16

2.12

DIVIDENDS DECLARED PER COMMON SHARE

$ 1.5800

$ 1.5050

$ 1.3950

$ (4.2)

$ 1.0

$ (5.7)

Revenue from Contract with Customer, Excluding Assessed Tax

2,069.8

2,175.5

2,211.7

Revenues from Alternative Revenue Programs

52.5

56.1

58.6

OPERATING REVENUES

Total operating revenues

2,122.3

2,231.6

2,270.3

Total cost of sales

644.6

786.9

892.5

OPERATING EXPENSES

464.4

492.5

473.8

391.3

355.0

321.6

97.2

89.5

88.2

Operating expenses

952.9

937.0

883.6

Allowance for equity funds used during construction

524.8

507.7

494.2

OTHER INCOME (EXPENSE)

4.8

4.5

23.8

Pension and Other Postretirement Benefits Cost (Reversal of Cost)

(3.1)

(1.2)

(8.9)

Other income

5.0

6.7

14.1

Other expense

(2.6)

(6.9)

(3.4)

Net other income (expense)

4.1

3.1

25.6

INTEREST EXPENSE

Interest on long-term debt

152.8

138.3

157.4

Allowance for borrowed funds used during construction

(1.9)

(2.8)

(11.7)

Interest on short-term debt and other interest charges

3.9

5.0

6.1

INCOME (LOSS) BEFORE TAXES

154.8

140.5

151.8

374.1

370.3

368.0

INCOME TAX EXPENSE (BENEFIT)

34.7

20.1

40.0

Net Income (Loss) Attributable to Parent

339.4

350.2

328.0

Comprehensive Income (Loss), Net of Tax, Attributable to Parent

0.0

$ 339.4

$ 350.2

$ 328.0

[1]

For the year ended December 31, 2020, Enable recorded a $225.0 million impairment on its SESH equity method investment. Enable estimated the fair value of this equity method investment was below the carrying value at September 30, 2020 and concluded the decline in value was other than temporary due to the expiration of a transportation contract and the current status of renewal negotiations. The impairment ran through OGE Energy's portion of Enable net income and was offset by basis differences that flow through the amortization of basis difference and dilution recognition line item above.

[2]

In March 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Notes 5 and 7.

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Net income (loss)	$ (173.7)	$ 433.6	$ 425.5
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss, net of tax of $1.2, $1.1 and $1.1, respectively	3.9	3.4	3.3
Net loss arising during the period, net of tax of ($1.7), ($2.6) and ($4.7), respectively	(5.1)	(8.3)	(14.1)
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax	2.2	8.6	4.7
Postretirement benefit plans:
Amortization of prior service credit, net of tax of ($0.6), ($0.6) and ($0.6), respectively	(1.7)	(1.7)	(1.7)
Amortization of deferred net gain, net of tax of $0.0, $0.0 and $0.0, respectively	(0.1)	(0.2)	0.0
Net gain (loss) arising during the period, net of tax of ($0.8), ($0.1) and $0.7, respectively	(2.4)	(0.2)	2.1
Curtailment cost, net of tax of ($0.1), $0.0 and $0.0, respectively	(0.3)	0.0	0.0
Other Comprehensive Income (Loss), Tax, Portion Attributable to Noncontrolling Interest	(0.2)	(0.2)	0.0
Other comprehensive income (loss), net of tax	(4.2)	1.0	(5.7)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest	0.7	0.6	0.0
Comprehensive income (loss)	$ (177.9)	$ 434.6	$ 419.8

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME Parenthetical - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss, net of tax of $1.2, $1.1 and $1.1, respectively	$ 1.2	$ 1.1	$ 1.1
Net loss arising during the period, net of tax of ($1.7), ($2.6) and ($4.7), respectively	(1.7)	(2.6)	(4.7)
Postretirement plans:
Amortization of deferred net gain, net of tax of $0.0, $0.0 and $0.0, respectively	0.0	0.0	0.0
Net gain (loss) arising during the period, net of tax of ($0.8), ($0.1) and $0.7, respectively	(0.8)	(0.1)	0.7
Amortization of prior service credit, net of tax of ($0.6), ($0.6) and ($0.6), respectively	(0.6)	(0.6)	(0.6)
Pension Plans [Member]
Pension Plan and Restoration of Retirement Income Plan:
Settlement cost, net of tax of $0.7, $2.7 and $1.6, respectively	0.7	2.7	1.6
Other Postretirement Benefits Plan [Member]
Pension Plan and Restoration of Retirement Income Plan:
Settlement cost, net of tax of $0.7, $2.7 and $1.6, respectively	$ (0.1)	$ 0.0
Postretirement plans:
Curtailment cost, net of tax of ($0.1), $0.0 and $0.0, respectively			$ 0.0

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

CASH FLOWS FROM OPERATING ACTIVITIES

Adjustments to reconcile net income (loss) to net cash provided from operating activities:

$ (173.7)

$ 433.6

$ 425.5

Deferred income taxes and investment tax credits, net

391.3

355.0

321.6

(134.5)

27.6

78.5

Equity in (earnings) losses of unconsolidated affiliates

^[1]

668.0

^[2]

(113.9)

(152.8)

Distributions from unconsolidated affiliates

91.7

125.5

141.2

Allowance for equity funds used during construction

(4.8)

(4.5)

(23.8)

Stock-based compensation expense

9.8

13.9

13.4

112.0

47.1

10.8

Change in certain current assets and liabilities:

(64.0)

(45.6)

(16.5)

Other assets

(9.2)

(3.8)

6.2

Other liabilities

(26.3)

19.2

1.0

Accounts receivable and accrued unbilled revenues, net

3.1

18.8

19.8

Income taxes receivable

2.8

(1.0)

(4.1)

Fuel, materials and supplies inventories

(8.9)

4.2

27.3

Fuel recoveries

63.3

(33.0)

(3.4)

Other current assets

(16.8)

5.1

25.1

Accounts payable

59.8

(34.5)

29.7

Other current liabilities

(26.8)

(38.0)

73.2

Net cash provided from operating activities

712.8

681.5

951.1

CASH FLOWS FROM INVESTING ACTIVITIES

Capital expenditures (less allowance for equity funds used during construction)

(650.5)

(635.5)

(573.6)

Return of capital - unconsolidated affiliates

(4.4)

(7.7)

(2.5)

0.0

18.5

0.0

Proceeds from sale of assets

0.0

0.1

Net cash used in investing activities

(654.9)

(624.7)

(576.0)

CASH FLOWS FROM FINANCING ACTIVITIES

Increase (decrease) in short-term debt

(17.0)

112.0

(168.4)

Proceeds from long-term debt

297.1

296.5

396.0

Payment of long-term debt

(0.1)

(250.1)

Dividends paid on common stock

(314.9)

(299.2)

(272.2)

Cash paid for employee equity-based compensation and expense of common stock

(7.1)

(10.3)

(0.5)

Purchase of treasury stock

(0.1)

0.0

(14.7)

0.0

Net cash used in financing activities

(56.8)

(151.1)

(295.2)

NET CHANGE IN CASH AND CASH EQUIVALENTS

1.1

(94.3)

79.9

CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR

0.0

94.3

14.4

CASH AND CASH EQUIVALENTS AT END OF YEAR

1.1

0.0

94.3

Interest costs capitalized

1.9

2.8

11.7

Interest (net of interest capitalized)

153.4

152.2

153.8

Income taxes (net of income tax refunds)

3.9

5.5

2.8

Power plant long-term service agreement

6.8

28.9

(9.2)

Adjustments to reconcile net income (loss) to net cash provided from operating activities:

Deferred income taxes and investment tax credits, net

391.3

355.0

321.6

40.9

20.4

56.6

Allowance for equity funds used during construction

(4.8)

(4.5)

(23.8)

Stock-based compensation expense

3.0

4.9

4.6

112.0

47.1

10.8

Change in certain current assets and liabilities:

(64.0)

(45.6)

(16.5)

Other assets

(3.4)

3.8

1.9

Other liabilities

(24.3)

8.4

0.0

Accounts receivable and accrued unbilled revenues, net

4.5

17.0

19.5

Fuel, materials and supplies inventories

(8.9)

4.2

27.3

Fuel recoveries

63.3

(33.0)

(3.4)

Other current assets

(17.3)

5.9

23.1

Accounts payable

64.8

(30.0)

19.0

Other current liabilities

(26.8)

(35.1)

72.5

Net cash provided from operating activities

640.4

573.8

804.0

CASH FLOWS FROM INVESTING ACTIVITIES

Capital expenditures (less allowance for equity funds used during construction)

(650.5)

(635.5)

(573.6)

Proceeds from sale of assets

0.0

0.1

Net cash used in investing activities

(650.5)

(635.5)

(573.5)

CASH FLOWS FROM FINANCING ACTIVITIES

Proceeds from long-term debt

297.1

296.5

396.0

Payment of long-term debt

(0.1)

(250.1)

Dividends paid on common stock

(325.0)

0.0

(185.0)

Net cash used in financing activities

10.1

61.7

(230.5)

NET CHANGE IN CASH AND CASH EQUIVALENTS

0.0

CASH AND CASH EQUIVALENTS AT BEGINNING OF YEAR

0.0

CASH AND CASH EQUIVALENTS AT END OF YEAR

0.0

Interest costs capitalized

1.9

2.8

11.7

Net Income (Loss) Attributable to Parent

339.4

350.2

328.0

Increase (Decrease) in Income Taxes Payable

(5.3)

(0.7)

(15.6)

Changes In Advances With Parent

38.1

15.3

(191.4)

Interest (net of interest capitalized)

150.2

144.6

149.7

Income taxes (net of income tax refunds)

(0.2)

1.3

0.9

Power plant long-term service agreement

$ 6.8

$ 28.9

$ (9.2)

[1]

[2]

In March 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Notes 5 and 7.

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
CURRENT ASSETS
Cash and cash equivalents	$ 1.1	$ 0.0
Accounts receivable, after allowance for doubtful accounts	157.8	153.8
Accrued unbilled revenues	67.6	64.7
Income taxes receivable	8.1	10.9
Fuel inventories	36.5	46.3
Materials and supplies, at average cost	116.2	90.6
Fuel clause under recoveries	0.0	39.5
Other	41.2	24.4
Total current assets	428.5	430.2
OTHER PROPERTY AND INVESTMENTS
Investment in unconsolidated affiliates	397.4	1,151.5
Other	86.7	82.7
Total other property and investments	484.1	1,234.2
PROPERTY, PLANT AND EQUIPMENT
In service	13,296.7	12,771.1
Construction work in progress	145.5	141.6
Total property, plant and equipment	13,442.2	12,912.7
Less: accumulated depreciation	4,067.6	3,868.1
Net property, plant and equipment	9,374.6	9,044.6
DEFERRED CHARGES AND OTHER ASSETS
Regulatory assets	415.6	306.0
Other	16.0	9.3
Total deferred charges and other assets	431.6	315.3
TOTAL ASSETS	10,718.8	11,024.3
Allowance for Doubtful Accounts Receivable	2.6	1.5
CURRENT LIABILITIES
Short-term debt	95.0	112.0
Accounts payable	251.5	194.9
Dividends payable	80.5	77.6
Customer deposits	81.1	83.0
Accrued taxes	55.7	41.9
Accrued interest	40.2	37.9
Accrued compensation	31.1	40.6
Long-term debt due within one year	0.0	0.0
Fuel clause over recoveries	28.6	4.8
Other	33.7	65.2
Total current liabilities	697.4	657.9
LONG-TERM DEBT	3,494.4	3,195.2
DEFERRED CREDITS AND OTHER LIABILITIES
Accrued benefit obligations	231.4	225.0
Deferred income taxes	1,268.6	1,375.8
Accumulated Deferred Investment Tax Credit	10.9	7.1
Regulatory liabilities	1,188.9	1,223.5
Other	195.4	200.3
Total deferred credits and other liabilities	2,895.2	3,031.7
Total liabilities	7,087.0	6,884.8
COMMITMENTS AND CONTINGENCIES (NOTE 15)
STOCKHOLDERS' EQUITY
Common stockholders' equity	1,124.6	1,131.3
Retained earnings	2,544.6	3,036.1
Accumulated other comprehensive loss, net of tax	(32.1)	(27.9)
Stockholders' Equity Attributable to Parent	3,631.8	4,139.5
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	10,718.8	11,024.3
Og and E [Member]
CURRENT ASSETS
Cash and cash equivalents	0.0	0.0
Accounts receivable, after allowance for doubtful accounts	156.3	153.8
Accrued unbilled revenues	67.7	64.7
Advances to parent	272.0	304.8
Fuel inventories	36.5	46.3
Materials and supplies, at average cost	116.2	90.6
Fuel clause under recoveries	0.0	39.5
Other	36.9	19.6
Total current assets	685.6	719.3
OTHER PROPERTY AND INVESTMENTS
Total other property and investments	4.1	4.7
PROPERTY, PLANT AND EQUIPMENT
In service	13,290.6	12,765.0
Construction work in progress	145.5	141.6
Total property, plant and equipment	13,436.1	12,906.6
Less: accumulated depreciation	4,067.6	3,868.1
Net property, plant and equipment	9,368.5	9,038.5
DEFERRED CHARGES AND OTHER ASSETS
Regulatory assets	415.6	306.0
Other	15.2	8.1
Total deferred charges and other assets	430.8	314.1
TOTAL ASSETS	10,489.0	10,076.6
CURRENT LIABILITIES
Accounts payable	236.7	175.0
Customer deposits	81.1	83.0
Accrued taxes	53.3	41.9
Accrued interest	40.2	37.9
Accrued compensation	22.5	29.5
Long-term debt due within one year	0.0	0.0
Fuel clause over recoveries	28.6	4.8
Other	33.5	65.1
Total current liabilities	495.9	437.2
LONG-TERM DEBT	3,494.4	3,195.2
DEFERRED CREDITS AND OTHER LIABILITIES
Accrued benefit obligations	135.4	133.3
Deferred income taxes	1,020.8	951.4
Accumulated Deferred Investment Tax Credit	10.9	7.1
Regulatory liabilities	1,188.9	1,223.5
Other	167.1	170.6
Total deferred credits and other liabilities	2,523.1	2,485.9
Total liabilities	6,513.4	6,118.3
COMMITMENTS AND CONTINGENCIES (NOTE 15)
STOCKHOLDERS' EQUITY
Common stockholders' equity	1,039.5	1,036.6
Retained earnings	2,936.1	2,921.7
Stockholders' Equity Attributable to Parent	3,975.6	3,958.3
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 10,489.0	$ 10,076.6

CONSOLIDATED BALANCE SHEETS Parenthetical - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Allowance for Doubtful Accounts Receivable	$ 2.6	$ 1.5

CONSOLIDATED STATEMENTS OF CAPITALIZATION - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Schedule of Capitalization, Long-term Debt [Line Items]
Common Stock, Value	$ 2.0	$ 2.0
Premium on common stock	1,122.6	1,129.3
Retained earnings	2,544.6	3,036.1
Accumulated other comprehensive loss, net of tax	$ (32.1)	$ (27.9)
Treasury Stock, Common, Shares	0.1	0.0
Treasury Stock, Value	$ (5.3)	$ 0.0
Total stockholders' equity	3,631.8	4,139.5
Unamortized debt expense	(25.3)	(24.2)
Total long-term debt	3,494.4	3,195.2
Less: long-term debt due within one year	0.0	0.0
Total long-term debt (excluding long-term debt due within one year)	3,494.4	3,195.2
Total capitalization (including long-term debt due within one year)	$ 7,126.2	$ 7,334.7
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	450.0	450.0
Common Stock, Shares, Outstanding	200.1	200.1
Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Common Stock, Value	$ 100.9	$ 100.9
Premium on common stock	938.6	935.7
Retained earnings	2,936.1	2,921.7
Total stockholders' equity	3,975.6	3,958.3
Unamortized debt expense	(25.3)	(24.2)
Unamortized discount	(10.1)	(10.5)
Total long-term debt	3,494.4	3,195.2
Less: long-term debt due within one year	0.0	0.0
Total long-term debt (excluding long-term debt due within one year)	3,494.4	3,195.2
Total capitalization (including long-term debt due within one year)	$ 7,470.0	$ 7,153.5
Common Stock, Par or Stated Value Per Share	$ 2.50	$ 2.50
Common Stock, Shares Authorized	100.0	100.0
Common Stock, Shares, Outstanding	40.4	40.4
Garfield Industrial Authority Bond [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Maturity Date	Jan. 01, 2025
Muskogee Industrial Authority Bond Due 2025 [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Maturity Date	Jan. 01, 2025
Muskogee Industrial Authority Bond Due 2027 [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Maturity Date	Jun. 01, 2027
Senior Notes [Member] \| Series Due July 15, 2027 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 125.0	$ 125.0
Debt Instrument, Interest Rate, Stated Percentage	6.65%
Debt Instrument, Maturity Date	Jul. 15, 2027
Senior Notes [Member] \| Series Due April 15, 2028 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 100.0	100.0
Debt Instrument, Interest Rate, Stated Percentage	6.50%
Debt Instrument, Maturity Date	Apr. 15, 2028
Senior Notes [Member] \| Series Due August 15, 2028 [Member] [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 400.0	400.0
Debt Instrument, Interest Rate, Stated Percentage	3.80%
Senior Notes [Member] \| Series Due March 15, 2030 \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 300.0	300.0
Debt Instrument, Interest Rate, Stated Percentage	3.30%
Debt Instrument, Maturity Date	Mar. 15, 2030
Senior Notes [Member] \| Series Due January 15, 2036 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 110.0	110.0
Debt Instrument, Interest Rate, Stated Percentage	5.75%
Debt Instrument, Maturity Date	Jan. 15, 2036
Senior Notes [Member] \| Series Due February 1, 2038 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 200.0	200.0
Debt Instrument, Interest Rate, Stated Percentage	6.45%
Debt Instrument, Maturity Date	Feb. 01, 2038
Senior Notes [Member] \| Series Due June 1, 2040 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt Instrument, Interest Rate, Stated Percentage	5.85%
Debt Instrument, Maturity Date	Jun. 01, 2040
Senior Notes [Member] \| Series Due May 15, 2041 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt Instrument, Interest Rate, Stated Percentage	5.25%
Debt Instrument, Maturity Date	May 15, 2041
Senior Notes [Member] \| Series Due May 1, 2043 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt Instrument, Interest Rate, Stated Percentage	3.90%
Debt Instrument, Maturity Date	May 01, 2043
Senior Notes [Member] \| Series Due March 15, 2044 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt Instrument, Interest Rate, Stated Percentage	4.55%
Debt Instrument, Maturity Date	Mar. 15, 2044
Senior Notes [Member] \| Series Due December 15, 2044 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt Instrument, Interest Rate, Stated Percentage	4.00%
Debt Instrument, Maturity Date	Dec. 15, 2044
Senior Notes [Member] \| Series due August 15, 2047 [Member] [Domain] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 300.0	300.0
Debt Instrument, Interest Rate, Stated Percentage	3.85%
Debt Instrument, Maturity Date	Aug. 15, 2047
Senior Notes [Member] \| Series due April 1, 2047 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 300.0	300.0
Debt Instrument, Interest Rate, Stated Percentage	4.15%
Debt Instrument, Maturity Date	Apr. 01, 2047
Senior Notes [Member] \| Series Due April 1, 2030 \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 300.0	0.0
Debt Instrument, Interest Rate, Stated Percentage	3.25%
Debt Instrument, Maturity Date	Apr. 01, 2030
Senior Notes [Member] \| Series due August 15, 2028 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Maturity Date	Aug. 15, 2028
Long-term Debt [Member] \| Due August 31, 2062 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 9.4	9.5
Debt Instrument, Interest Rate, Stated Percentage	3.80%
Debt Instrument, Maturity Date	Aug. 31, 2062
Debentures Subject to Mandatory Redemption [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Total long-term debt	$ 135.4
Debentures Subject to Mandatory Redemption [Member] \| Garfield Industrial Authority Bond [Member] \| Minimum [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.28%
Debentures Subject to Mandatory Redemption [Member] \| Garfield Industrial Authority Bond [Member] \| Maximum [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.35%
Debentures Subject to Mandatory Redemption [Member] \| Garfield Industrial Authority Bond [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 47.0	47.0
Debentures Subject to Mandatory Redemption [Member] \| Muskogee Industrial Authority Bond Due 2025 [Member] \| Minimum [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.33%
Debentures Subject to Mandatory Redemption [Member] \| Muskogee Industrial Authority Bond Due 2025 [Member] \| Maximum [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.31%
Debentures Subject to Mandatory Redemption [Member] \| Muskogee Industrial Authority Bond Due 2025 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 32.4	32.4
Debentures Subject to Mandatory Redemption [Member] \| Muskogee Industrial Authority Bond Due 2027 [Member] \| Minimum [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.28%
Debentures Subject to Mandatory Redemption [Member] \| Muskogee Industrial Authority Bond Due 2027 [Member] \| Maximum [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.35%
Debentures Subject to Mandatory Redemption [Member] \| Muskogee Industrial Authority Bond Due 2027 [Member] \| Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 56.0	$ 56.0

CONSOLIDATED STATEMENTS OF CAPITALIZATION (Parenthetical) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	450.0	450.0
Common Stock, Shares, Outstanding	200.1	200.1
OG&E [Member]
Common Stock, Par or Stated Value Per Share	$ 2.50	$ 2.50
Common Stock, Shares Authorized	100.0	100.0
Common Stock, Shares, Outstanding	40.4	40.4
Garfield Industrial Authority, January 1, 2025 [Member]
Debt Instrument, Maturity Date	Jan. 01, 2025
Muskogee Industrial Authority, Janaury 1, 2025 [Member]
Debt Instrument, Maturity Date	Jan. 01, 2025
Muskogee Industrial Authority, June 1, 2027 [Member]
Debt Instrument, Maturity Date	Jun. 01, 2027
Senior Notes [Member] \| Series Due July 15, 2027 [Member] \| OG&E [Member]
Debt Instrument, Maturity Date	Jul. 15, 2027
Debt Instrument, Interest Rate, Stated Percentage	6.65%
Senior Notes [Member] \| Series Due April 15, 2028 [Member] \| OG&E [Member]
Debt Instrument, Maturity Date	Apr. 15, 2028
Debt Instrument, Interest Rate, Stated Percentage	6.50%
Senior Notes [Member] \| Series Due August 15, 2028 [Member] [Member] \| OG&E [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.80%
Senior Notes [Member] \| Series Due March 15, 2030 \| OG&E [Member]
Debt Instrument, Maturity Date	Mar. 15, 2030
Debt Instrument, Interest Rate, Stated Percentage	3.30%
Senior Notes [Member] \| Series Due January 15, 2036 [Member] \| OG&E [Member]
Debt Instrument, Maturity Date	Jan. 15, 2036
Debt Instrument, Interest Rate, Stated Percentage	5.75%
Senior Notes [Member] \| Series Due February 1, 2038 [Member] \| OG&E [Member]
Debt Instrument, Maturity Date	Feb. 01, 2038
Debt Instrument, Interest Rate, Stated Percentage	6.45%
Senior Notes [Member] \| Series Due June 1, 2040 [Member] \| OG&E [Member]
Debt Instrument, Maturity Date	Jun. 01, 2040
Debt Instrument, Interest Rate, Stated Percentage	5.85%
Senior Notes [Member] \| Series Due May 15, 2041 [Member] \| OG&E [Member]
Debt Instrument, Maturity Date	May 15, 2041
Debt Instrument, Interest Rate, Stated Percentage	5.25%
Senior Notes [Member] \| Series Due May 1, 2043 [Member] \| OG&E [Member]
Debt Instrument, Maturity Date	May 01, 2043
Debt Instrument, Interest Rate, Stated Percentage	3.90%
Senior Notes [Member] \| Series Due March 15, 2044 [Member] \| OG&E [Member]
Debt Instrument, Maturity Date	Mar. 15, 2044
Debt Instrument, Interest Rate, Stated Percentage	4.55%
Senior Notes [Member] \| Series Due December 15, 2044 [Member] \| OG&E [Member]
Debt Instrument, Maturity Date	Dec. 15, 2044
Debt Instrument, Interest Rate, Stated Percentage	4.00%
Senior Notes [Member] \| Series due April 1, 2047 [Member] \| OG&E [Member]
Debt Instrument, Maturity Date	Apr. 01, 2047
Debt Instrument, Interest Rate, Stated Percentage	4.15%
Senior Notes [Member] \| Series due August 15, 2047 [Member] [Domain] \| OG&E [Member]
Debt Instrument, Maturity Date	Aug. 15, 2047
Debt Instrument, Interest Rate, Stated Percentage	3.85%
Long-term Debt [Member] \| Due August 31, 2062 [Member] \| OG&E [Member]
Debt Instrument, Maturity Date	Aug. 31, 2062
Debt Instrument, Interest Rate, Stated Percentage	3.80%
Minimum [Member] \| Debentures Subject to Mandatory Redemption [Member] \| Garfield Industrial Authority, January 1, 2025 [Member]
Debt Instrument, Interest Rate, Stated Percentage	0.28%
Minimum [Member] \| Debentures Subject to Mandatory Redemption [Member] \| Muskogee Industrial Authority, Janaury 1, 2025 [Member]
Debt Instrument, Interest Rate, Stated Percentage	0.33%
Minimum [Member] \| Debentures Subject to Mandatory Redemption [Member] \| Muskogee Industrial Authority, June 1, 2027 [Member]
Debt Instrument, Interest Rate, Stated Percentage	0.28%
Maximum [Member] \| Debentures Subject to Mandatory Redemption [Member] \| Garfield Industrial Authority, January 1, 2025 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.35%
Maximum [Member] \| Debentures Subject to Mandatory Redemption [Member] \| Muskogee Industrial Authority, Janaury 1, 2025 [Member]
Debt Instrument, Interest Rate, Stated Percentage	4.31%
Maximum [Member] \| Debentures Subject to Mandatory Redemption [Member] \| Muskogee Industrial Authority, June 1, 2027 [Member]
Debt Instrument, Interest Rate, Stated Percentage	5.35%

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Premium on Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Common Stock, Shares, Outstanding		199,700
Comprehensive income (loss)
Treasury Stock, Common, Shares						0
Net Income (Loss), Including portion attributable to noncontrolling interest, Number of Shares		0				0
Balance at Dec. 31, 2017	$ 3,851.1	$ 2.0	$ 1,112.8	$ 2,759.5	$ (23.2)	$ 0.0
Comprehensive income (loss)
Net income (loss)	425.5	$ 0.0	0.0	425.5	0.0	$ 0.0
Other Comprehensive Income (Loss), Net of Tax, Number of Shares		0				0
Other Comprehensive Income (Loss), Net of Tax	(5.7)	$ 0.0	0.0	0.0	(5.7)	$ 0.0
Dividends, Common Stock, Cash, Number of Shares		0				0
Dividends declared on common stock	(278.7)	$ 0.0	0.0	(278.7)	0.0	$ 0.0
Stock Issued During Period, Shares, New Issues		0				0
Purchase of treasury stock	(0.1)	$ 0.0	(0.1)	0.0	0.0	$ 0.0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares		0				0
Stock-based compensation	13.0	$ 0.0	13.0	0.0	0.0	$ 0.0
Balance at Dec. 31, 2018	$ 4,005.1	$ 2.0	1,125.7	2,906.3	(28.9)	$ 0.0
Comprehensive income (loss)
DIVIDENDS DECLARED PER COMMON SHARE	$ 1.3950
Common Stock, Shares, Outstanding		199,700
Treasury Stock, Common, Shares						0
Net Income (Loss), Including portion attributable to noncontrolling interest, Number of Shares		0				0
Net income (loss)	$ 433.6	$ 0.0	0.0	433.6	0.0	$ 0.0
Other Comprehensive Income (Loss), Net of Tax, Number of Shares		0				0
Other Comprehensive Income (Loss), Net of Tax	1.0	$ 0.0	0.0	0.0	1.0	$ 0.0
Dividends, Common Stock, Cash, Number of Shares		0				0
Dividends declared on common stock	(303.8)	$ 0.0	0.0	(303.8)	0.0	$ 0.0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares		400				0
Stock-based compensation	3.6	$ 0.0	3.6	0.0	0.0	$ 0.0
Balance at Dec. 31, 2019	$ 4,139.5	$ 2.0	1,129.3	3,036.1	(27.9)	$ 0.0
Comprehensive income (loss)
DIVIDENDS DECLARED PER COMMON SHARE	$ 1.5050
Common Stock, Shares, Outstanding	200,100	200,100
Treasury Stock, Common, Shares	0					0
Net Income (Loss), Including portion attributable to noncontrolling interest, Number of Shares		0				0
Net income (loss)	$ (173.7)	$ 0.0	0.0	(173.7)	0.0	$ 0.0
Other Comprehensive Income (Loss), Net of Tax, Number of Shares		0				0
Other Comprehensive Income (Loss), Net of Tax	(4.2)	$ 0.0	0.0	0.0	(4.2)	$ 0.0
Dividends, Common Stock, Cash, Number of Shares		0				0
Dividends declared on common stock	(317.8)	$ 0.0	0.0	(317.8)	0.0	$ 0.0
Treasury Stock, Value, Acquired, Cost Method		$ 0.0	0.0	0.0	0.0	$ (14.7)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares		0				(300)
Stock-based compensation	2.7	$ 0.0	(6.7)	0.0	0.0	$ 9.4
Balance at Dec. 31, 2020	$ 3,631.8	$ 2.0	$ 1,122.6	$ 2,544.6	$ (32.1)	$ (5.3)
Comprehensive income (loss)
DIVIDENDS DECLARED PER COMMON SHARE	$ 1.5800
Treasury Stock, Shares, Acquired	405	0				400
Common Stock, Shares, Outstanding	200,100	200,100
Treasury Stock, Common, Shares	100					100

STATEMENTS OF CHANGES IN STOCKHOLDER'S EQUITY - USD ($) shares in Millions, $ in Millions	Total	Og and E [Member]	Common Stock	Common Stock Og and E [Member]	Premium on Common Stock	Premium on Common Stock Og and E [Member]	Retained Earnings	Retained Earnings Og and E [Member]
Common Stock, Shares, Outstanding			199.7	40.4
Stockholders' Equity Attributable to Parent		$ 3,455.7		$ 100.9		$ 926.3		$ 2,428.5
Net Income (Loss), Including portion attributable to noncontrolling interest, Number of Shares			0.0	0.0
Net Income (Loss) Attributable to Parent		328.0		$ 0.0		0.0		328.0
Dividends, Common Stock, Cash, Number of Shares			0.0	0.0
Dividends, Common Stock		(185.0)		$ 0.0		0.0		(185.0)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares			0.0	0.0
Stock-based compensation	$ 13.0	4.6	$ 0.0	$ 0.0	$ 13.0	4.6	$ 0.0	0.0
Common Stock, Shares, Outstanding			199.7	40.4
Stockholders' Equity Attributable to Parent		3,603.3		$ 100.9		930.9		2,571.5
Net Income (Loss), Including portion attributable to noncontrolling interest, Number of Shares			0.0	0.0
Net Income (Loss) Attributable to Parent		350.2		$ 0.0		0.0		350.2
Dividends, Common Stock, Cash, Number of Shares			0.0
Dividends, Common Stock								0.0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares			0.4	0.0
Stock-based compensation	$ 3.6	$ (4.8)	$ 0.0	$ 0.0	3.6	(4.8)	0.0	0.0
Common Stock, Shares, Outstanding	200.1	40.4	200.1	40.4
Stockholders' Equity Attributable to Parent	$ 4,139.5	$ 3,958.3		$ 100.9		935.7		2,921.7
Net Income (Loss), Including portion attributable to noncontrolling interest, Number of Shares			0.0	0.0
Net Income (Loss) Attributable to Parent		339.4		$ 0.0		0.0		339.4
Dividends, Common Stock, Cash, Number of Shares			0.0	0.0
Dividends, Common Stock		(325.0)		$ 0.0		0.0		325.0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares			0.0	0.0
Stock-based compensation	$ 2.7	$ 2.9	$ 0.0	$ 0.0	$ (6.7)	2.9	$ 0.0	0.0
Common Stock, Shares, Outstanding	200.1	40.4	200.1	40.4
Stockholders' Equity Attributable to Parent	$ 3,631.8	$ 3,975.6		$ 100.9		$ 938.6		$ 2,936.1

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2020

Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]

Summary of Significant Accounting Policies

Organization

OGE Energy is a holding company with investments in energy and energy services providers offering physical delivery and related services for both electricity and natural gas primarily in the south central U.S. OGE Energy conducts these activities through two business segments: (i) electric utility and (ii) natural gas midstream operations. The accounts of OGE Energy and its wholly-owned subsidiaries, including OG&E, are included in OGE Energy's consolidated financial statements. All intercompany transactions and balances are eliminated in such consolidation. OGE Energy generally uses the equity method of accounting for investments where its ownership interest is between 20 percent and 50 percent and it lacks the power to direct activities that most significantly impact economic performance.

OG&E. OGE Energy's electric utility operations are conducted through OG&E, which generates, transmits, distributes and sells electric energy in Oklahoma and western Arkansas. OG&E's rates are subject to regulation by the OCC, the APSC and the FERC. OG&E was incorporated in 1902 under the laws of the Oklahoma Territory and is a wholly-owned subsidiary of OGE Energy. OG&E is the largest electric utility in Oklahoma, and its franchised service territory includes Fort Smith, Arkansas and the surrounding communities. OG&E sold its retail natural gas business in 1928 and is no longer engaged in the natural gas distribution business.

Enable. OGE Energy's natural gas midstream operations segment represents OGE Energy's investment in Enable. The investment in Enable is held through wholly-owned subsidiaries and ultimately OGE Holdings. Enable is primarily engaged in the business of gathering, processing, transporting and storing natural gas. Enable's natural gas gathering and processing assets are strategically located in four states and serve natural gas production in the Anadarko, Arkoma and Ark-La-Tex Basins. Enable also owns crude oil gathering assets in the Anadarko and Williston Basins. Enable has intrastate natural gas transportation and storage assets that are located in Oklahoma as well as interstate assets that extend from western Oklahoma and the Texas Panhandle to Louisiana, from Louisiana to Illinois and from Louisiana to Alabama. Enable's general partner is equally controlled by OGE Energy and CenterPoint, who each have 50 percent management ownership. Based on the 50/50 management ownership, with neither company having control, OGE Energy accounts for its interest in Enable using the equity

method of accounting. In February 2021, Enable entered into a definitive merger agreement with Energy Transfer. For further discussion, see Note 5.

OGE Energy charges operating costs to OG&E and Enable based on several factors. Operating costs directly related to OG&E and Enable are assigned as such. Operating costs incurred for the benefit of OG&E and Enable are allocated either as overhead based primarily on labor costs or using the "Distrigas" method. The "Distrigas" method is a three-factor formula that uses an equal weighting of payroll, net operating revenues and gross property, plant and equipment. OGE Energy adopted this method as a result of a recommendation by the OCC Staff. OGE Energy believes this method provides a reasonable basis for allocating common expenses.

Use of Estimates

In preparing the financial statements, management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and contingent liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Changes to these assumptions and estimates could have a material effect on the Registrants' financial statements. However, the Registrants believe they have taken reasonable positions where assumptions and estimates are used in order to minimize the negative financial impact to the Registrants that could result if actual results vary from the assumptions and estimates. In management's opinion, the areas where the most significant judgment is exercised include the determination of Pension Plan assumptions, income taxes, contingency reserves, asset retirement obligations, regulatory assets and liabilities, unbilled revenues and the allowance for uncollectible accounts receivable. For OGE Energy, significant judgment is also exercised in the determination of any impairment of equity method investments.

Cash and Cash Equivalents

For purposes of the financial statements, the Registrants consider all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. These investments are carried at cost, which approximates fair value.

Allowance for Uncollectible Accounts Receivable

Customer balances are generally written off if not collected within six months after the final billing date. The allowance for uncollectible accounts receivable for OG&E is generally calculated by multiplying the last six months of electric revenue by the provision rate, which is based on a 12-month historical average of actual balances written off and is adjusted for current conditions and supportable forecasts as necessary. To the extent the historical collection rates, when incorporating forecasted conditions, are not representative of future collections, there could be an effect on the amount of uncollectible expense recognized, such as in response to COVID-19 impacts. Also, a portion of the uncollectible provision related to fuel within the Oklahoma jurisdiction is being recovered through the fuel adjustment clause. The allowance for uncollectible accounts receivable is a reduction to Accounts Receivable in the balance sheets and is included in Other Operation and Maintenance Expense in the statements of income. The allowance for uncollectible accounts receivable was $2.6 million and $1.5 million at December 31, 2020 and 2019, respectively.

New business customers are required to provide a security deposit in the form of cash, bond or irrevocable letter of credit that is refunded when the account is closed. New residential customers whose outside credit scores indicate an elevated risk are required to provide a security deposit that is refunded based on customer protection rules defined by the OCC and the APSC. The payment behavior of all existing customers is continuously monitored, and, if the payment behavior indicates sufficient risk within the meaning of the applicable utility regulation, customers will be required to provide a security deposit.

The Registrants considered COVID-19 pandemic impacts when calculating their reserve on accounts receivable as of December 31, 2020, as further discussed within "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations - Recent Developments."

Investment in Unconsolidated Affiliates

OGE Energy's investment in Enable is considered to be a variable interest entity because the owners of the equity at risk in this entity have disproportionate voting rights in relation to their obligations to absorb the entity's expected losses or to receive its expected residual returns. However, OGE Energy is not considered the primary beneficiary of Enable since it does not have the power to direct the activities of Enable that are considered most significant to the economic performance of Enable; therefore, OGE Energy accounts for its investment in Enable using the equity method of accounting. Under the equity method, the investment will be adjusted each period for contributions made, distributions received and OGE Energy's share of the investee's comprehensive income as adjusted for basis differences. OGE Energy's maximum exposure to loss related to Enable is limited to its equity investment in Enable at December 31, 2020 as presented in Note 14. OGE Energy evaluates its equity method investments for impairment when events or changes in circumstances indicate there is a loss in value of the investment that is other than a temporary decline. When indicators exist, the fair value is estimated and compared to the investment carrying value, and if any impairment is judgmentally determined to be other than temporary, the carrying value of the investment is written down to fair value.

OGE Energy determined, effective March 31, 2020, that an other than temporary decline in the value of OGE Energy's investment in Enable had occurred. Further information detailing the results of OGE Energy's impairment analysis and fair value measurement can be found in Notes 5 and 7, respectively.

OGE Energy considers distributions received from Enable which do not exceed cumulative equity in earnings subsequent to the date of investment to be a return on investment and are classified as operating activities in the statements of cash flows. OGE Energy considers distributions received from Enable in excess of cumulative equity in earnings subsequent to the date of investment to be a return of investment and are classified as investing activities in the statements of cash flows.

Allowance for Funds Used During Construction

Allowance for funds used during construction, a non-cash item, is reflected as an increase to Net Other Income and a reduction to Interest Expense in the statements of income and as an increase to Construction Work in Progress in the balance sheets. Allowance for funds used during construction is calculated according to the FERC requirements for the imputed cost of equity and borrowed funds. Allowance for funds used during construction rates, compounded semi-annually, were 7.3 percent, 7.6 percent and 7.6 percent for the years ended December 31, 2020, 2019 and 2018, respectively.

Collection of Sales Tax

In the normal course of its operations, OG&E collects sales tax from its customers. OG&E records a current liability for sales taxes when it bills its customers and eliminates this liability when the taxes are remitted to the appropriate governmental authorities. OG&E excludes the sales tax collected from its operating revenues.

Revenue Recognition

General

OG&E recognizes revenue from electric sales when power is delivered to customers. The performance obligation to deliver electricity is generally created and satisfied simultaneously, and the provisions of the regulatory-approved tariff determine the charges OG&E may bill the customer, payment due date and other pertinent rights and obligations of both parties. OG&E measures its customers' metered usage and sends bills to its customers throughout each month. As a result, there is a significant amount of customers' electricity consumption that has not been billed at the end of each month. OG&E accrues an estimate of the revenues for electric sales delivered since the latest billings. Unbilled revenue is presented in Accrued Unbilled Revenues in the balance sheets and in Revenues from Contracts with Customers in the statements of income based on estimates of usage and prices during the period. The estimates that management uses in this calculation could vary from the actual amounts to be paid by customers.

Integrated Market and Transmission

OG&E currently owns and operates transmission and generation facilities as part of a vertically integrated utility. OG&E is a member of the SPP regional transmission organization and has transferred operational authority, but not ownership, of OG&E's transmission facilities to the SPP. The SPP has implemented FERC-approved regional day-ahead and real-time markets for energy and operating services, as well as associated transmission congestion rights. Collectively, the three markets operate together under the global name, SPP Integrated Marketplace. OG&E represents owned and contracted generation assets and customer load in the SPP Integrated Marketplace for the sole benefit of its customers. OG&E has not participated in the SPP Integrated Marketplace for any speculative trading activities.

OG&E records the SPP Integrated Marketplace transactions as sales or purchases per FERC Order 668, which requires that purchases and sales be recorded on a net basis for each settlement period of the SPP Integrated Marketplace. Purchases and sales are based on the fixed transaction price determined by the market at the time of the purchase or sale and the MWh quantity purchased or sold. These results are reported as Revenues from Contracts with Customers or Cost of Sales in the statements of income. OG&E revenues, expenses, assets and liabilities may be adversely affected by changes in the organization, operating and regulation by the FERC or the SPP.

OG&E's transmission revenues are generated by the use of OG&E's transmission network by the SPP, which operates the network, on behalf of other transmission owners. OG&E recognizes revenue on the sale of transmission service to its customers over time as the service is provided in the amount OG&E has a right to invoice. Transmission service to the SPP is billed monthly based on a fixed transaction price determined by OG&E's FERC-approved formula transmission rates along with other SPP-specific charges and the megawatt quantity reserved.

Other Revenues

Other Revenues in the statements of income is comprised of certain rider revenue that includes alternative revenue measures as defined in ASC 980, "Regulated Operations," which details two types of alternative revenue programs. The first type adjusts billings for the effects of weather abnormalities or broad external factors or to compensate OG&E for demand-side management initiatives (i.e., no-growth plans and similar conservation efforts). The second type provides for additional billings (i.e., incentive awards) for the achievement of certain objectives, such as reducing costs, reaching specified milestones or demonstratively improving customer service. Once the specific events permitting billing of the additional revenues under either

program type have been completed, OG&E recognizes the additional revenues if (i) the program is established by an order from OG&E's regulatory commission that allows for automatic adjustment of future rates; (ii) the amount of additional revenues for the period is objectively determinable and is probable of recovery; and (iii) the additional revenues will be collected within 24 months following the end of the annual period in which they are recognized.

Fuel Adjustment Clauses

The actual cost of fuel used in electric generation and certain purchased power costs are passed through to OG&E's customers through fuel adjustment clauses. The fuel adjustment clauses are subject to periodic review by the OCC and the APSC.

LeasesThe Registrants evaluate all contracts under ASC 842 to determine if the contract is or contains a lease and to determine classification as an operating or finance lease. If a lease is identified, the Registrants recognize a right-of-use asset and a lease liability in their balance sheets. The Registrants recognize and measure a lease liability when they conclude the contract contains an identified asset that the Registrants control through having the right to obtain substantially all of the economic benefits and the right to direct the use of the identified asset. The liability is equal to the present value of lease payments, and the asset is based on the liability, subject to adjustment, such as for initial direct costs. Further, the Registrants utilize an incremental borrowing rate for purposes of measuring lease liabilities, if the discount rate is not implicit in the lease. To calculate the incremental borrowing rate, the Registrants start with a current pricing report for their senior unsecured notes, which indicates rates for periods reflective of the lease term, and adjust for the effects of collateral to arrive at the secured incremental borrowing rate. As permitted by ASC 842, the Registrants made an accounting policy election to not apply the balance sheet recognition requirements to short-term leases and to not separate lease components from non-lease components when recognizing and measuring lease liabilities. For income statement purposes, the Registrants record operating lease expense on a straight-line basis.

Income Taxes

OGE Energy files consolidated income tax returns in the U.S. federal jurisdiction and various state jurisdictions. OG&E is a part of the consolidated tax return of OGE Energy. Income taxes are generally allocated to each company in the affiliated group, including OG&E, based on its stand-alone taxable income or loss. Federal investment tax credits previously claimed on electric utility property have been deferred and will be amortized to income over the life of the related property. The Registrants use the asset and liability method of accounting for income taxes. Under this method, a deferred tax asset or liability is recognized for the estimated future tax effects attributable to temporary differences between the financial statement basis and the tax basis of assets and liabilities as well as tax credit carry forwards and net operating loss carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period of the change. The Registrants recognize interest related to unrecognized tax benefits in Interest Expense and recognize penalties in Other Expense in the statements of income.

Accrued Vacation

The Registrants accrue vacation pay monthly by establishing a liability for vacation earned. Vacation may be taken as earned and is charged against the liability. At the end of each year, the liability represents the amount of vacation earned but not taken.

Comprehensive Income (Loss) Note [Text Block]

Accumulated Other Comprehensive Income (Loss)

The following table presents changes in the components of accumulated other comprehensive income (loss) attributable to OGE Energy during 2019 and 2020. All amounts below are presented net of tax.


	Pension Plan and Restoration of Retirement Income Plan		Postretirement Benefit Plans
(In millions)	Net Gain (Loss)		Net Gain (Loss)		Prior Service Cost (Credit)		Other Comprehensive Loss from Unconsolidated Affiliates		Total





Balance at December 31, 2018	$	(38.8)	$	4.6	$	5.3	$	—	$	(28.9)
Other comprehensive loss before reclassifications	(8.3)		(0.2)		—		(0.6)		(9.1)
Amounts reclassified from accumulated other comprehensive income (loss)	3.4		(0.2)		(1.7)		—		1.5

Settlement cost	8.6		—		—		—		8.6
Net current period other comprehensive income (loss)	3.7		(0.4)		(1.7)		(0.6)		1.0
Balance at December 31, 2019	(35.1)		4.2		3.6		(0.6)		(27.9)
Other comprehensive income (loss) before reclassifications	(5.1)		(2.4)		—		(0.7)		(8.2)
Amounts reclassified from accumulated other comprehensive income (loss)	3.9		(0.1)		(1.7)		—		2.1
Curtailment cost	—		(0.3)		—		—		(0.3)
Settlement cost	2.2		—		—		—		2.2
Net current period other comprehensive income (loss)	1.0		(2.8)		(1.7)		(0.7)		(4.2)
Balance at December 31, 2020	$	(34.1)	$	1.4	$	1.9	$	(1.3)	$	(32.1)

The following table presents significant amounts reclassified out of accumulated other comprehensive income (loss) by the respective line items in net income (loss) during the years ended December 31, 2020 and 2019.


Details about Accumulated Other Comprehensive Income (Loss) Components	Amount Reclassified from Accumulated Other Comprehensive Income (Loss)				Affected Line Item in OGE Energy's Statements of Income
	Year Ended December 31,
(In millions)	2020		2019









Amortization of Pension Plan and Restoration of Retirement Income Plan items:
Actuarial losses	$	(5.1)	$	(4.5)	(A)

Settlement cost	(2.9)		(11.3)		(A)
	(8.0)		(15.8)		Income (Loss) Before Taxes
	(1.9)		(3.8)		Income Tax Expense (Benefit)


	$	(6.1)	$	(12.0)	Net Income (Loss)

Amortization of postretirement benefit plans items:

Prior service credit	$	2.3	$	2.3	(A)
Curtailment cost	0.4		—		(A)
Actuarial gains	0.1		0.2		(A)
	2.8		2.5		Income (Loss) Before Taxes
	0.7		0.6		Income Tax Expense (Benefit)
	$	2.1	$	1.9	Net Income (Loss)



Total reclassifications for the period, net of tax	$	(4.0)	$	(10.1)	Net Income (Loss)

(A)These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost (see Note 13 for additional information).

Asset Retirement Obligation Disclosure [Text Block]

OG&E has asset retirement obligations primarily associated with the removal of company-owned wind turbines on leased land, as well as the removal of asbestos from certain power generating stations. OG&E has recorded asset retirement obligations that are being accreted over their respective lives ranging from five to 68 years. Asset retirement obligations are included in Other Deferred Credits in the Registrants' balance sheets.

The following table presents changes to OG&E's asset retirement obligations during the years ended December 31, 2020 and 2019.


(In millions)	2020		2019
Balance at January 1	$	73.5	$	83.9
Accretion expense	0.5		1.0
Revisions in estimated cash flows (A)	5.8		(2.4)

Liabilities settled (B)	(0.2)		(9.0)
Balance at December 31	$	79.6	$	73.5

(A)Assumptions changed related to the estimated timing and estimated cost of the removal of asbestos at OG&E's generating facilities.

(B)Asset retirement obligations were settled for asbestos removal at one of OG&E's generating facilitiesAccruals for environmental costs are recognized when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated. Costs are charged to expense or deferred as a regulatory asset based on expected recovery from customers in future rates, if they relate to the remediation of conditions caused by past operations or if they are not expected to mitigate or prevent contamination from future operations. Where environmental expenditures relate to facilities currently in use, such as pollution control equipment, the costs may be capitalized and depreciated over the future service periods. Estimated remediation costs are recorded at undiscounted amounts, independent of any insurance or rate recovery, based on prior experience, assessments and current technology. Accrued obligations are regularly adjusted as environmental assessments and estimates are revised and remediation efforts proceed. For sites where OG&E has been designated as one of several potentially responsible parties, the amount accrued represents OG&E's estimated share of the cost. OG&E had $25.0 million and $18.7 million in accrued environmental liabilities at December 31, 2020 and 2019, respectively, which are included in OG&E's asset retirement obligations.

Property, Plant and Equipment Disclosure [Text Block]

Property, Plant and Equipment

All property, plant and equipment is recorded at cost. Newly constructed plant is added to plant balances at cost which includes contracted services, direct labor, materials, overhead, transportation costs and the allowance for funds used during construction. Replacements of units of property are capitalized as plant. For assets that belong to a common plant account, the replaced plant is removed from plant balances, and the cost of such property net of any salvage proceeds is charged to Accumulated Depreciation. For assets that do not belong to a common plant account, the replaced plant is removed from plant balances with the related accumulated depreciation, and the remaining balance net of any salvage proceeds is recorded as a loss in the statements of income as Other Expense. Repair and replacement of minor items of property are included in the statements of income as Other Operation and Maintenance Expense.

The following tables present OG&E's ownership interest in the jointly-owned McClain Plant and the jointly-owned Redbud Plant, and, as disclosed below, only OG&E's ownership interest is reflected in the property, plant and equipment and accumulated depreciation balances in these tables. The owners of the remaining interests in the McClain Plant and the Redbud Plant are responsible for providing their own financing of capital expenditures. Also, only OG&E's proportionate interests of any direct expenses of the McClain Plant and the Redbud Plant, such as fuel, maintenance expense and other operating expenses, are included in the applicable financial statement captions in the statements of income.


December 31, 2020 (In millions)	Percentage Ownership		Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
McClain Plant (A)	77	%	$	257.1	$	96.0	$	161.1
Redbud Plant (A)(B)	51	%	$	531.8	$	181.9	$	349.9

(A)Construction work in progress was $0.1 million and $1.8 million for the McClain and Redbud Plants, respectively.

(B)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $67.3 million.


December 31, 2019 (In millions)	Percentage Ownership		Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
McClain Plant (A)	77	%	$	254.4	$	83.5	$	170.9
Redbud Plant (A)(B)	51	%	$	529.9	$	159.0	$	370.9

(A)Construction work in progress was $0.2 million and $1.4 million for the McClain and Redbud Plants, respectively.

(B)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $61.8 million.

The following tables present the Registrants' major classes of property, plant and equipment and related accumulated depreciation.


December 31, 2020 (In millions)	Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
OG&E:
Distribution assets	$	4,809.9	$	1,422.1	$	3,387.8
Electric generation assets (A)	4,932.2		1,713.6		3,218.6
Transmission assets (B)	2,944.6		591.7		2,352.9
Intangible plant	254.1		153.9		100.2
Other property and equipment	495.3		186.3		309.0
OG&E property, plant and equipment	13,436.1		4,067.6		9,368.5
Non-OG&E property, plant and equipment	6.1		—		6.1
Total OGE Energy property, plant and equipment	$	13,442.2	$	4,067.6	$	9,374.6

(A)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $67.3 million.

(B)This amount includes a plant acquisition adjustment of $3.3 million and accumulated amortization of $0.9 million.


December 31, 2019 (In millions)	Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
OG&E:
Distribution assets	$	4,468.6	$	1,381.1	$	3,087.5
Electric generation assets (A)	4,838.6		1,601.0		3,237.6
Transmission assets (B)	2,901.1		565.5		2,335.6
Intangible plant	225.2		145.4		79.8
Other property and equipment	473.1		175.1		298.0
OG&E property, plant and equipment	12,906.6		3,868.1		9,038.5
Non-OG&E property, plant and equipment	6.1		—		6.1
Total OGE Energy property, plant and equipment	$	12,912.7	$	3,868.1	$	9,044.6

(A)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $61.8 million.

(B)This amount includes a plant acquisition adjustment of $3.3 million and accumulated amortization of $0.8 million.

OG&E's unamortized computer software costs, included in intangible plant above, were $89.7 million and $71.3 million at December 31, 2020 and 2019, respectively. OG&E's amortization expense for computer software costs was $14.9 million, $11.0 million and $9.6 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Depreciation and Amortization

The provision for depreciation, which was 2.6 percent and 2.7 percent of the average depreciable utility plant for 2020 and 2019, respectively, is calculated using the straight-line method over the estimated service life of the utility assets. Depreciation is provided at the unit level for production plant and at the account or sub-account level for all other plant and is based on the average life group method. In 2021, the provision for depreciation is projected to be 2.6 percent of the average depreciable utility plant.

Amortization of intangible assets is calculated using the straight-line method. Of the remaining amortizable intangible plant balance at December 31, 2020, 99.0 percent will be amortized over 10.4 years with the remaining 1.0 percent of the intangible plant balance at December 31, 2020 being amortized over 23.7 years.

Amortization of plant acquisition adjustments is provided on a straight-line basis over the estimated remaining service life of the acquired assets. Plant acquisition adjustments include $148.3 million for the Redbud Plant, which is being amortized over a 27 year life, and $3.3 million for certain transmission substation facilities in OG&E's service territory, which is being amortized over a 37 to 59 year period.

Inventory Disclosure [Text Block]

Fuel Inventories

Fuel inventories for the generation of electricity consist of coal, natural gas and oil. OG&E uses the weighted-average cost method of accounting for inventory that is physically added to or withdrawn from storage or stockpiles. The amount of fuel inventory was $36.5 million and $46.3 million at December 31, 2020 and 2019, respectively.

Summary of Significant Accounting Policies [Text Block]

Accounting Records

The accounting records of OG&E are maintained in accordance with the Uniform System of Accounts prescribed by the FERC and adopted by the OCC and the APSC. Additionally, OG&E, as a regulated utility, is subject to accounting principles for certain types of rate-regulated activities, which provide that certain incurred costs that would otherwise be charged to expense can be deferred as regulatory assets, based on the expected recovery from customers in future rates. Likewise, certain actual or anticipated credits that would otherwise reduce expense can be deferred as regulatory liabilities, based on the expected flowback to customers in future rates. Management's expected recovery of deferred costs and flowback of deferred credits generally results from specific decisions by regulators granting such ratemaking treatment.

OG&E records certain incurred costs and obligations as regulatory assets or liabilities if, based on regulatory orders or other available evidence, it is probable that the costs or obligations will be included in amounts allowable for recovery or refund in future rates.

The following table presents a summary of OG&E's regulatory assets and liabilities.


December 31 (In millions)	2020		2019
REGULATORY ASSETS
Current:
SPP cost tracker under recovery (A)	$	7.0	$	—
Generation Capacity Replacement rider under recovery (A)	4.4		3.7
Fuel clause under recoveries	—		39.5

Other (A)	8.4		5.5
Total current regulatory assets	$	19.8	$	48.7
Non-current:
Benefit obligations regulatory asset	$	164.9	$	167.2
Deferred storm expenses	158.8		65.5
Sooner Dry Scrubbers	19.7		20.6
Pension tracker	18.1		2.3
Smart Grid	11.2		18.4
Unamortized loss on reacquired debt	9.7		10.6
Arkansas deferred pension expenses	9.3		8.0

Frontier Plant deferred expenses	6.4		—
COVID-19 impacts	6.4		—
Other	11.1		13.4
Total non-current regulatory assets	$	415.6	$	306.0
REGULATORY LIABILITIES
Current:
Fuel clause over recoveries	$	28.6	$	4.8
Oklahoma demand program rider over recovery (B)	1.5		2.0
Reserve for tax refund and interim surcharge (B)	0.8		12.7
SPP cost tracker over recovery (B)	—		2.6

Other (B)	4.2		6.9
Total current regulatory liabilities	$	35.1	$	29.0
Non-current:
Income taxes refundable to customers, net	$	867.4	$	899.2
Accrued removal obligations, net	316.8		318.5

Other	4.7		5.8
Total non-current regulatory liabilities	$	1,188.9	$	1,223.5

(A)Included in Other Current Assets in the balance sheets.

(B)Included in Other Current Liabilities in the balance sheets.

OG&E recovers certain SPP costs related to base plan charges from its customers and refunds certain SPP revenues received to its customers in Oklahoma through the SPP cost tracker and in Arkansas through the transmission cost recovery rider.

OG&E recovers the Oklahoma jurisdictional portion of costs, including non-fuel operation and maintenance expenses, depreciation, taxes other than income taxes and a return on capital, for its investment in the River Valley plant through the Generation Capacity Replacement Rider. The OCC also authorized OG&E to defer the same costs related to its investment in the Frontier plant to a regulatory asset, and recovery of these costs will be considered in future rate proceedings.

Fuel clause under and over recoveries are generated from OG&E's customers when OG&E's cost of fuel either exceeds or is less than the amount billed to its customers, respectively. OG&E's fuel recovery clauses are designed to smooth the impact of fuel price volatility on customers' bills. As a result, OG&E under recovers fuel costs in periods of rising fuel prices above the

baseline charge for fuel and over recovers fuel costs when prices decline below the baseline charge for fuel. Provisions in the fuel clauses are intended to allow OG&E to amortize under and over recovery balances.

The benefit obligations regulatory asset is comprised of expenses recorded which are probable of future recovery and that have not yet been recognized as components of net periodic benefit cost, including net loss and prior service cost. These expenses are recorded as a regulatory asset as OG&E historically has recovered and currently recovers pension and postretirement benefit plan expense in its electric rates. If, in the future, the regulatory bodies indicate a change in policy related to the recovery of pension and postretirement benefit plan expenses, this could cause the benefit obligations regulatory asset balance to be reclassified to accumulated other comprehensive income.

The following table presents a summary of the components of the benefit obligations regulatory asset.


December 31 (In millions)	2020		2019
Pension Plan and Restoration of Retirement Income Plan:
Net loss	$	147.3	$	160.5

Postretirement Benefit Plans:
Net loss	26.2		23.3
Prior service cost	(8.6)		(16.6)
Total	$	164.9	$	167.2

OG&E includes in expense any Oklahoma storm-related operation and maintenance expenses up to $2.7 million annually and defers to a regulatory asset any additional expenses incurred over $2.7 million. OG&E expects to recover the amounts deferred each year over a five-year period in accordance with historical practice.

As approved by the OCC, OG&E deferred the non-fuel incremental operation and maintenance expenses, depreciation, debt cost associated with the capital investment and related ad valorem taxes for the Dry Scrubbers at Sooner Units 1 and 2 as a regulatory asset, and these costs are being recovered over 25 years.

OG&E recovers specific amounts of pension and postretirement medical costs in rates approved in its Oklahoma rate reviews. In accordance with approved orders, OG&E defers the difference between actual pension and postretirement medical expenses and the amount approved in its last Oklahoma rate review as a regulatory asset or regulatory liability. These amounts have been recorded in the Pension tracker regulatory asset in the table above.

OG&E deferred to a regulatory asset the incremental and stranded costs that were accumulated during Smart Grid deployment, including (i) costs for web portal access, (ii) costs for education and home energy reports and (iii) stranded costs associated with OG&E's analog electric meters, which have been replaced by smart meters. As approved by the OCC and APSC, these costs are being recovered over a six-year period ending in 2022 in Oklahoma and 2023 in Arkansas.

Unamortized loss on reacquired debt is comprised of unamortized debt issuance costs related to the early retirement of OG&E's long-term debt. These amounts are recorded in interest expense and are being amortized over the term of the long-term debt which replaced the previous long-term debt. The unamortized loss on reacquired debt is recovered as a part of OG&E's cost of capital.

Arkansas includes a certain level of pension expense in base rates. When the Pension Plan experiences a settlement, which represents an acceleration of future pension costs, OG&E defers to a regulatory asset the Arkansas jurisdictional portion of each settlement, which historically has been recovered from customers over the average life of the remaining plan participants. A portion of these settlements is being recovered in current rates, and recovery of additional amounts will be requested as additional settlements occur. For additional information related to settlements, see Note 13.

In response to the COVID-19 pandemic, the OCC and APSC issued orders allowing OG&E to defer certain expenses related to its COVID-19 response. For additional information about these orders, see Note 16 and "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations - Recent Developments."

OG&E recovers program costs related to the Demand and Energy Efficiency Program in Oklahoma through the Demand Program Rider, which operates on a three-year program cycle. The current program cycle, which runs through 2021, includes recovery of (i) energy efficiency program costs, (ii) lost revenues associated with certain achieved energy efficiency and demand savings, (iii) performance-based incentives and (iv) costs associated with research and development investments.

As a result of filings with the OCC, APSC and FERC, OG&E established mechanisms to refund to customers the amount of excess taxes received through rates, with an ongoing adjustment for any excess accumulated deferred income taxes resulting from the Tax Cuts and Jobs Act of 2017. Additional amounts due to customers will be refunded in accordance with agreements in each jurisdiction.

Income taxes refundable to customers, net, represents the reduction in accumulated deferred income taxes resulting from the reduction in the federal income tax rate as part of the Tax Cuts and Jobs Act of 2017 and includes income taxes recoverable from customers that represent income tax benefits previously used to reduce OG&E's revenues (treated as regulatory assets). These liabilities will be returned to customers in varying amounts over approximately 80 years, and the assets will be amortized over the estimated remaining life of the assets to which they relate, as the temporary differences that generated the income tax benefits turn around.

Accrued removal obligations, net represents asset retirement costs previously recovered from ratepayers for other than legal obligations. Management continuously monitors the future recoverability of regulatory assets. When in management's judgment future recovery becomes impaired, the amount of the regulatory asset is adjusted, as appropriate. If OG&E were required to discontinue the application of accounting principles for certain types of rate-regulated activities for some or all of its operations, it could result in writing off the related regulatory assets or liabilities, which could have significant financial effects.

Reclassifications [Text Block]

ReclassificationsCertain prior year amounts have been reclassified to conform to the current year presentation.

Accounting Pronouncements

12 Months Ended

Dec. 31, 2020

Accounting Pronouncement [Abstract]

New Accounting Pronouncements and Changes in Accounting Principles [Text Block]

Accounting Pronouncements

Recently Adopted Accounting Standards

The following table presents an overview of recently adopted accounting standards and their impacts on the Registrants.


ASU Number and Name	Description	Date of Adoption	Financial Statements and Disclosures Impact
ASU 2016-13, "Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Information"	This standard requires entities to measure all expected credit losses of financial assets held at a reporting date based on historical experience, current conditions and reasonable and supportable forecasts in order to record credit losses in a more timely manner.	January 1, 2020	Utilizing a modified-retrospective approach, the Registrants determined their only financial instrument requiring measurement under ASU 2016-13 is trade receivables. The Registrants consider both future economic conditions and historical data to measure their reserves for trade receivables under this standard and determined no adjustments to their reserves were necessary upon adoption.
ASU 2018-15, "Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40)"	The standard aligns requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software.	January 1, 2020	The new standard did not have a material effect on the Registrants' financial statements upon adoption. Prospectively, the Registrants record applicable capitalized implementation costs in Other Current Assets in the balance sheets and related amortization expense in Other Operation and Maintenance in the statements of income.
ASU 2018-13, "Fair Value Measurement (Topic 820): Disclosure Framework"	The standard removes, adds or modifies disclosure requirements that impact all levels of the fair value hierarchy, as well as investments measured using the net asset value practical expedient.	January 1, 2020	The Registrants applied the guidance on a retrospective or prospective basis, depending on the requirement, and did not experience a significant impact on their financial statement disclosures.
ASU 2018-14, "Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20)"	The standard removes, adds or clarifies disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans.	January 1, 2020	The Registrants applied the guidance on a retrospective basis and did not experience a significant impact on their financial statement disclosures.
ASU 2020-04, "Reference Rate Reform (Topic 848)"	This standard provides optional expedients and exceptions, if certain criteria are met, for applying GAAP to contracts, hedging relationships and other transactions that reference LIBOR or another reference rate expected to be discontinued because of reference rate reform.	January 1, 2020	The guidance did not have a material impact upon adoption, nor do the Registrants expect a material impact in the future, on their financial statements.

The Registrants believe that other recently adopted and recently issued accounting standards that are not yet effective do not appear to have a material impact on the Registrants' financial position, results of operations or cash flows upon adoption.

The entire disclosure for change in accounting principle. Includes, but is not limited to, nature, reason, and method of adopting amendment to accounting standards or other change in accounting principle.

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Revenue from Contract with Customer [Abstract]

Revenue from Contracts with Customers (Notes)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Text Block]

Revenue Recognition

The following table presents OG&E's revenues from contracts with customers disaggregated by customer classification. OG&E's operating revenues disaggregated by customer classification can be found in "OG&E (Electric Utility) Results of Operations" within "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations."




	Year Ended December 31,
(In millions)	2020		2019		2018
Residential	$	842.7	$	865.8	$	877.8
Commercial	465.6		486.6		500.0
Industrial	192.6		217.8		228.9
Oilfield	169.2		200.4		190.4
Public authorities and street light	172.3		190.3		197.4
System sales revenues	1,842.4		1,960.9		1,994.5
Provision for rate refund	3.8		(0.9)		(6.0)
Integrated market	49.6		38.4		48.7
Transmission	143.3		148.0		147.4
Other	30.7		29.1		27.1
Revenues from contracts with customers	$	2,069.8	$	2,175.5	$	2,211.7

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

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Leases, Codification Topic 842

12 Months Ended

Dec. 31, 2020

Schedule of Equity Method Investments [Line Items]

Lessee, Operating Leases

Leases

Based on their evaluation of all contracts under ASC 842, as described in Note 1, the Registrants concluded they have operating lease obligations for OG&E's railcar leases, testing equipment and wind farm land leases. OGE Energy also has an operating lease obligation for its office space lease.

Operating Leases

OG&E Railcar Lease Agreement

Effective February 1, 2019, OG&E renewed a railcar lease agreement for 780 rotary gondola railcars to transport coal from Wyoming to OG&E's coal-fired generation units. Rental payments are charged to fuel expense and are recovered through OG&E's fuel adjustment clauses. On February 1, 2024, OG&E has the option to either purchase the railcars at a stipulated fair market value or renew the lease. If OG&E chooses not to purchase the railcars or renew the lease agreement and the actual fair value of the railcars is less than the stipulated fair market value, OG&E would be responsible for the difference in those values up to a maximum of $6.8 million.

OG&E Testing Equipment Lease Agreement

Effective January 1, 2020, OG&E entered into a noncancellable engineering testing equipment lease agreement, with a term of January 1, 2020 to December 31, 2022.

OG&E Wind Farm Land Lease Agreements

OG&E has operating leases related to land for OG&E's Centennial, OU Spirit and Crossroads wind farms with terms of 25 to 30 years. The Centennial lease has rent escalations which increase annually based on the Consumer Price Index. While lease liabilities are not remeasured as a result of changes to the Consumer Price Index, changes to the Consumer Price Index are treated as variable lease payments and recognized in the period in which the obligation for those payments was incurred. The OU Spirit and Crossroads leases have rent escalations which increase after five and 10 years. Although the leases are cancellable, OG&E is required to make annual lease payments as long as the wind turbines are located on the land. OG&E does not expect to terminate the leases until the wind turbines reach the end of their useful life.

OGE Energy Office Space Lease

OGE Energy has a noncancellable office space lease agreement, with a term from September 1, 2018 to August 31, 2021, that allows for leasehold improvements.

Financial Statement Information and Maturity Analysis of Lease Liabilities

OGE Energy's operating lease cost was $6.4 million, $6.0 million and $4.9 million for the years ended December 31, 2020, 2019 and 2018, respectively. OG&E's operating lease cost was $5.5 million, $5.1 million and $4.1 million for the years ended December 31, 2020, 2019 and 2018, respectively.

The following table presents amounts recognized for operating leases in the Registrants' cash flow statements and balance sheets and supplemental information related to those amounts recognized.


	OGE Energy						OG&E
	Year Ended December 31,						Year Ended December 31,
(In millions)	2020			2019			2020			2019












Cash paid for amounts included in the measurement of lease liabilities:

Operating cash flows for operating leases	$	6.4		$	5.6		$	5.5		$	4.8

Right-of-use assets obtained in exchange for new operating lease liabilities	$	1.4		$	10.7		$	1.4		$	10.7




(Dollars in millions)	December 31, 2020			December 31, 2019			December 31, 2020			December 31, 2019
Right-of-use assets at period end (A)	$	37.6		$	40.9		$	37.0		$	39.6
Operating lease liabilities at period end (B)	$	42.3		$	45.8		$	41.7		$	44.3
Operating lease weighted-average remaining lease term (in years)	12.5			13.1			12.7			13.5
Operating lease weighted-average discount rate	3.9		%	3.9		%	3.9		%	3.9		%

(A)Included in Property, Plant and Equipment in the Registrants' balance sheets.

(B)Included in Other Deferred Credits and Other Liabilities in the Registrants' balance sheets.

The following table presents a maturity analysis of the Registrants' operating lease liabilities.



Future minimum operating lease payments as of December 31:	OGE Energy		OG&E
(In millions)

2021	$	6.3	$	5.7
2022	5.7		5.7
2023	5.1		5.1
2024	3.2		3.2
2025	3.0		3.0
Thereafter	31.7		31.7
Total future minimum lease payments	55.0		54.4
Less: Imputed interest	12.7		12.7
Present value of net minimum lease payments	$	42.3	$	41.7

Investment in Unconsolidated Affiliate

12 Months Ended

Dec. 31, 2020

Equity Method Investments and Joint Ventures Disclosure [Text Block]

Investment in Unconsolidated Affiliates

In 2013, OGE Energy, CenterPoint and the ArcLight group formed Enable as a private limited partnership, and OGE Energy and the ArcLight group indirectly contributed 100 percent of the equity interests in Enogex LLC to Enable. OGE Energy determined that its contribution of Enogex LLC to Enable met the requirements of being in substance real estate and recorded the contribution at historical cost. The formation of Enable was considered a business combination, and CenterPoint was the acquirer of Enogex Holdings for accounting purposes. Under this method, the fair value of the consideration paid by CenterPoint for Enogex Holdings was allocated to the assets acquired and liabilities assumed based on their fair value. Enogex Holdings' assets, liabilities and equity were accordingly adjusted to estimated fair value, resulting in an increase to Enable's equity of $2.2 billion. Since the contribution of Enogex LLC to Enable was recorded at historical cost, the effects of the amortization and depreciation expense associated with the fair value adjustments on Enable's results of operations have been eliminated in OGE Energy's recording of its equity in earnings of Enable. As prior real estate sales accounting guidance was superseded by ASU 2017-05, "Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets," OGE Energy recognizes gains or losses on sales or dilution events in its investment in Enable within OGE Energy's earnings, net of proportional basis difference recognition.

At December 31, 2020, OGE Energy owned 111.0 million common units, or 25.5 percent, of Enable's outstanding common units. On December 31, 2020, Enable's common unit price closed at $5.26. OGE Energy recorded equity in losses of unconsolidated affiliates of $668.0 million for the year ended December 31, 2020 compared to equity in earnings of unconsolidated affiliates of $113.9 million and $152.8 million for the years ended 2019 and 2018, respectively. Equity in earnings (losses) of unconsolidated affiliates includes OGE Energy's share of Enable's earnings adjusted for the amortization of the basis difference of OGE Energy's original investment in Enogex LLC and its underlying equity in the net assets of Enable, as well as any impairment OGE Energy records on its investment in Enable. Equity in earnings (losses) of unconsolidated affiliates is also adjusted for the elimination of the Enogex Holdings fair value adjustments, as described above. These amortizations may also include gain or loss on dilution, net of proportional basis difference recognition.

OGE Energy evaluates its equity method investment for impairment when factors indicate that a decline in the value of its investment has occurred and the carrying amount of its investment may not be recoverable. An impairment loss, based on the excess of the carrying value over estimated fair value of the investment, is recognized in earnings when an impairment is deemed to be other than temporary. Considerable judgment is used in determining if an impairment loss is other than temporary and the amount of any impairment. Effective March 31, 2020, OGE Energy estimated the fair value of its investment in Enable was below the book value and concluded the decline in value was not temporary due to the severity of the decline and the recent rapid deterioration, as well as the near term future outlook, of the midstream oil and gas industry. Accordingly, OGE Energy recorded a $780.0 million impairment on its investment in Enable in March 2020, which is included in Equity in Earnings (Losses) of Unconsolidated Affiliates in OGE Energy's 2020 income statement. Further information concerning the fair value method used to measure the impairment on OGE Energy's investment in Enable can be found in Note 7.

The following tables present summarized unaudited financial information for 100 percent of Enable as of December 31, 2020 and 2019 and for the years ended December 31, 2020, 2019 and 2018.


	December 31,
Balance Sheet	2020		2019
(In millions)
Current assets	$	381	$	389
Non-current assets	$	11,348	$	11,877
Current liabilities	$	582	$	780
Non-current liabilities	$	4,052	$	4,077


	Year Ended December 31,
Income Statement	2020		2019		2018
(In millions)
Total revenues	$	2,463	$	2,960	$	3,431
Cost of natural gas and NGLs	$	965	$	1,279	$	1,819
Operating income	$	465	$	569	$	648
Net income	$	52	$	360	$	485

The following table presents a reconciliation of OGE Energy's equity in earnings (losses) of unconsolidated affiliates for the years ended December 31, 2020, 2019 and 2018. For further discussion of Enable's net income, see "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations - Results of Operations - OGE Holdings (Natural Gas Midstream Operations)."


	Year Ended December 31,
(In millions)	2020			2019			2018
Enable net income	$	52.0		$	360.0		$	485.3



OGE Energy's percent ownership at period end	25.5		%	25.5		%	25.6		%
OGE Energy's portion of Enable net income	$	13.2		$	91.8		$	124.4
Amortization of basis difference and dilution recognition (A)	98.8			22.1			28.4
Impairment of OGE Energy's equity method investment in Enable	(780.0)			—			—
Equity in earnings (losses) of unconsolidated affiliates (B)	$	(668.0)		$	113.9		$	152.8

(A) Includes loss on dilution, net of proportional basis difference recognition.

(B)For the year ended December 31, 2020, Enable recorded a $225.0 million impairment on its SESH equity method investment. Enable estimated the fair value of this equity method investment was below the carrying value at September 30, 2020 and concluded the decline in value was other than temporary due to the expiration of a transportation contract and the current status of renewal negotiations. The impairment ran through OGE Energy's portion of Enable net income and was offset by basis differences that flow through the amortization of basis difference and dilution recognition line item above.

The following table presents a reconciliation of the difference between OGE Energy's investment in Enable and its underlying equity in the net assets of Enable (basis difference) from December 31, 2019 to December 31, 2020. The basis difference is being amortized over approximately 30 years.


(In millions)
Basis difference at December 31, 2019	$	652.5

Amortization of basis difference (A)	(100.2)
Impairment of OGE Energy's equity method investment in Enable	780.0
Basis difference at December 31, 2020	$	1,332.3

(A) Includes proportional basis difference recognition due to dilution.

On April 1, 2020, Enable announced a 50 percent reduction to its quarterly distribution in order to strengthen its balance sheet and increase its annualized retained cash flow. See "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations - Recent Developments" for further discussion of OGE Energy's response.

On February 12, 2021, Enable announced a quarterly dividend distribution of $0.16525 per unit on its outstanding common units, which is unchanged from the previous quarter. If cash distributions to Enable's unitholders exceed $0.330625 per unit in any quarter, the general partner will receive increasing percentages, up to 50 percent, of the cash Enable distributes in excess of that amount. OGE Energy is entitled to 60 percent of those "incentive distributions." In certain circumstances, the general partner has the right to reset the minimum quarterly distribution and the target distribution levels at which the incentive distributions receive increasing percentages to higher levels based on Enable's cash distributions at the time of the exercise of this reset election.

Distributions received from Enable were $91.7 million, $144.0 million and $141.2 million during the years ended December 31, 2020, 2019 and 2018, respectively.

On February 16, 2021, Enable entered into a definitive merger agreement with Energy Transfer, pursuant to which, and subject to the conditions of the merger agreement, all outstanding common units of Enable will be acquired by Energy Transfer in an all-equity transaction. Under the terms of the merger agreement, Enable's common unitholders, including OGE Energy, will receive 0.8595 of one common unit representing limited partner interests in Energy Transfer for each common unit of Enable. The transaction is anticipated to close in 2021. The transaction is subject to the receipt of the required approvals from the holders of a majority of Enable's common units, anti-trust approvals and other customary closing conditions. Assuming the transaction closes, OGE Energy will own approximately three percent of Energy Transfer's outstanding limited partner units in lieu of the 25.5 percent interest in Enable that it currently owns.

Contemporaneously with the execution of the merger agreement, OGE Energy entered into a support agreement with Enable and Energy Transfer in which OGE Energy has agreed to vote its common units in favor of the merger. In addition, the merger agreement contemplates a registration rights agreement with Energy Transfer to be executed at the closing of the merger that provides for customary resale registration, demand registration and piggy-back registration rights with respect to Energy Transfer common units issued to OGE Energy in the merger.

Related Party Disclosures

12 Months Ended

Dec. 31, 2020

Related Party Transactions Disclosure

Related Party Transactions

OGE Energy charges operating costs to OG&E and Enable based on several factors, and operating costs directly related to OG&E and/or Enable are assigned as such. Operating costs incurred for the benefit of OG&E are allocated either as overhead based primarily on labor costs or using the "Distrigas" method, which is a three-factor formula that uses an equal weighting of payroll, net operating revenues and gross property, plant and equipment.

OGE Energy and OG&E

OGE Energy charged operating costs to OG&E of $140.6 million, $149.8 million and $140.9 million during the years ended December 31, 2020, 2019 and 2018, respectively. In 2020 and 2018, OG&E declared dividends to OGE Energy of $325.0 million and $185.0 million, respectively. In 2019, no dividends were declared from OG&E to OGE Energy.

OGE Energy and Enable

OGE Energy and Enable are currently parties to several agreements whereby OGE Energy provides specified support services to Enable, such as certain information technology, payroll and benefits administration. Under these agreements, OGE Energy charged operating costs to Enable of $0.4 million, $0.5 million and $0.6 million for December 31, 2020, 2019 and 2018, respectively.

Pursuant to a seconding agreement, OGE Energy provides seconded employees to Enable to support Enable's operations. As of December 31, 2020, 76 employees that participate in OGE Energy's defined benefit and retirement plans are seconded to Enable. OGE Energy billed Enable for reimbursement of $17.3 million, $23.2 million and $27.5 million in 2020, 2019 and 2018, respectively, under the seconding agreement for employment costs. If the seconding agreement were terminated, and those employees were no longer employed by OGE Energy, and lump sum payments were made to those employees, OGE Energy would recognize a settlement or curtailment of the pension/retiree health care charges, which would increase expense at OGE Energy by $19.0 million. Settlement and curtailment charges associated with the Enable seconded employees are not reimbursable to OGE Energy by Enable. The seconding agreement can be terminated by mutual agreement of OGE Energy and Enable or solely by OGE Energy upon 120 days' notice.

OGE Energy had accounts receivable from Enable for amounts billed for support services, including the cost of seconded employees, of $2.0 million and $0.8 million as of December 31, 2020 and 2019, which are included in Accounts Receivable in OGE Energy's balance sheets.

Assuming the pending merger between Enable and Energy Transfer is completed, these agreements between OGE Energy and Enable pursuant to which OGE Energy provides support services and seconded employees will be terminated.

OG&E and Enable

Enable provides gas transportation services to OG&E pursuant to agreements, which expire in May 2024 and December 2038, that grant Enable the responsibility of delivering natural gas to OG&E's generating facilities and performing an imbalance service. With this imbalance service, in accordance with the cash-out provision of the contract, OG&E purchases gas from Enable when Enable's deliveries exceed OG&E's pipeline receipts. Enable purchases gas from OG&E when OG&E's pipeline receipts exceed Enable's deliveries. Further, an additional gas transportation services contract with Enable became effective in December 2018 related to the project to convert Muskogee Units 4 and 5 from coal to natural gas. The following table presents summarized related party transactions between OG&E and Enable during the years ended December 31, 2020, 2019 and 2018.


	Year Ended December 31,
(In millions)	2020		2019		2018
Operating revenues:
Electricity to power electric compression assets	$	15.1	$	15.9	$	16.3
Cost of sales:
Natural gas transportation services	$	32.8	$	41.2	$	37.9

Natural gas purchases (sales)	$	2.7	$	(6.0)	$	(3.2)

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

The classification of the Registrants' fair value measurements requires judgment regarding the degree to which market data is observable or corroborated by observable market data. GAAP establishes a fair value hierarchy that prioritizes the inputs used to measure fair value based on observable and unobservable data. The hierarchy categorizes the inputs into three levels, with the highest priority given to quoted prices in active markets for identical unrestricted assets or liabilities (Level 1) and the lowest priority given to unobservable inputs (Level 3). Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The three levels defined in the fair value hierarchy are as follows:

Level 1 inputs are quoted prices in active markets for identical unrestricted assets or liabilities that are accessible at the measurement date.

Level 2 inputs are inputs other than quoted prices in active markets included within Level 1 that are either directly or indirectly observable at the reporting date for the asset or liability for substantially the full term of the asset or liability. Level 2 inputs include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active.

Level 3 inputs are prices or valuation techniques for the asset or liability that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). Unobservable inputs reflect the reporting entity's own assumptions about the assumptions that market participants would use in pricing the asset or liability (including assumptions about risk).

The Registrants had no financial instruments measured at fair value on a recurring basis at December 31, 2020 and 2019. The following table presents the carrying amount and fair value of the Registrants' financial instruments at December 31, 2020 and 2019, as well as the classification level within the fair value hierarchy.


	2020				2019
December 31 (In millions)	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Classification
Long-term Debt (including Long-term Debt due within one year):
OG&E Senior Notes	$	3,349.6	$	4,182.1	$	3,050.3	$	3,500.4	Level 2
OG&E Industrial Authority Bonds	$	135.4	$	135.4	$	135.4	$	135.4	Level 2
Tinker Debt	$	9.4	$	10.7	$	9.5	$	10.0	Level 3

Nonrecurring Fair Value Measurements

As further discussed in Note 5, OGE Energy recorded an impairment on its investment in Enable in March 2020. The nonrecurring fair value measurement consisted of calculating a 20-trading day volume weighted average price for Enable's common units through March 31, 2020. This method of valuation was determined to be representative of the fair value of Enable's common units as it incorporated market prices during the period and reduced the impact of volatility that a single day could represent. OGE Energy concluded that this valuation method resulted in a Level 3 nonrecurring fair value measurement.

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

Disclosure of Compensation Related Costs, Share-based Payments [Text Block]

Stock Based Compensation

12 Months Ended

Dec. 31, 2020

Stock-Based Compensation [Abstract]

Stock-Based Compensation

In 2013, OGE Energy adopted, and its shareholders approved, the Stock Incentive Plan. Under the Stock Incentive Plan, restricted stock, restricted stock units, stock options, stock appreciation rights and performance units may be granted to officers, directors and other key employees of OGE Energy and its subsidiaries, including OG&E. OGE Energy has authorized the issuance of up to 7,400,000 shares under the Stock Incentive Plan.

The following table presents the Registrants' pre-tax compensation expense and related income tax benefit for the years ended December 31, 2020, 2019 and 2018 related to performance units and restricted stock units for the Registrants' employees.


	OGE Energy						OG&E
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018
Performance units:
Total shareholder return	$	7.9	$	8.7	$	8.2	$	2.3	$	3.0	$	2.8
Earnings per share	1.0		4.3		5.1		0.3		1.5		1.8
Total performance units	8.9		13.0		13.3		2.6		4.5		4.6
Restricted stock units	0.9		0.9		0.1		0.4		0.4		—


Total compensation expense	$	9.8	$	13.9	$	13.4	$	3.0	$	4.9	$	4.6
Income tax benefit	$	2.5	$	3.6	$	3.4	$	0.8	$	1.3	$	1.2

During the year ended December 31, 2020, OGE Energy purchased 405,000 shares of its common stock, and 247,252 of these shares were used during the same period to satisfy payouts of earned performance units and restricted stock unit grants to the Registrants' employees pursuant to OGE Energy's Stock Incentive Plan. OGE Energy intends to use the remaining shares to satisfy payouts of earned performance units and restricted stock unit grants to employees pursuant to its Stock Incentive Plan. The shares were purchased at an average cost of $38.04 and $33.14 per share on the open market during March 2020 and August 2020, respectively. OGE Energy records treasury stock purchases at cost. Treasury stock is presented as a reduction of stockholders' equity in OGE Energy's 2020 balance sheet.

During the year ended December 31, 2020, there was an immaterial number of shares of new common stock issued pursuant to OGE Energy's Stock Incentive Plan to satisfy restricted stock unit grants to employees.

Performance Units

Under the Stock Incentive Plan, OGE Energy has issued performance units which represent the value of one share of OGE Energy's common stock. The performance units provide for accelerated vesting if there is a change in control (as defined in the Stock Incentive Plan). Each performance unit is subject to forfeiture if the recipient terminates employment with OGE Energy or a subsidiary prior to the end of the primarily three-year award cycle for any reason other than death, disability or retirement. In the event of death, disability or retirement, a participant will receive a prorated payment based on such participant's number of full months of service during the award cycle, further adjusted based on the achievement of the performance goals during the award cycle. The Registrants estimate expected forfeitures in accounting for performance unit compensation expense.

The performance units granted based on total shareholder return are contingently awarded and will be payable in shares of OGE Energy's common stock subject to the condition that the number of performance units, if any, earned by the employees upon the expiration of a primarily three-year award cycle (i.e., three-year cliff vesting period) is dependent on OGE Energy's total shareholder return ranking relative to a peer group of companies. The performance units granted based on earnings per share are contingently awarded and will be payable in shares of OGE Energy's common stock based on OGE Energy's earnings per share growth over a primarily three-year award cycle (i.e., three-year cliff vesting period) compared to a target set at the time of the grant by the Compensation Committee of OGE Energy's Board of Directors. All of these performance units are classified as equity in the balance sheets. If there is no or only a partial payout for the performance units at the end of the award cycle, the unearned performance units are cancelled. Payout requires approval of the Compensation Committee of OGE Energy's Board of Directors. Payouts, if any, are all made in common stock and are considered made when the payout is approved by the Compensation Committee.

Performance Units – Total Shareholder Return


	OGE Energy									OG&E
	2020			2019			2018			2020			2019			2018
Number of units granted	201,552			208,647			261,916			67,975			68,396			91,940
Fair value of units granted	$	38.03		$	47.00		$	36.86		$	38.03		$	47.00		$	36.86
Expected dividend yield	3.5		%	4.0		%	3.6		%	3.5		%	4.0		%	3.6		%
Expected price volatility	15.0		%	17.0		%	19.0		%	15.0		%	17.0		%	19.0		%
Risk-free interest rate	1.17		%	2.47		%	2.38		%	1.17		%	2.47		%	2.38		%
Expected life of units (in years)	2.85			2.86			2.86			2.85			2.86			2.86

Performance Units – Earnings Per Share

The fair value of the performance units based on earnings per share is based on grant date fair value which is equivalent to the price of one share of OGE Energy's common stock on the date of grant. The fair value of performance units based on earnings per share varies as the number of performance units that will vest is based on the grant date fair value of the units and the probable outcome of the performance condition. OGE Energy reassesses at each reporting date whether achievement of the performance condition is probable and accrues compensation expense if and when achievement of the performance condition is probable. As a result, the compensation expense recognized for these performance units can vary from period to period. There are no post-vesting restrictions related to OGE Energy's performance units based on earnings per share. In 2019, the Compensation Committee of OGE Energy's Board of Directors voted to grant restricted stock units in lieu of performance units based on earnings per share. For 2018, 87,308 and 30,649 performance units based on earnings per share were granted to OGE Energy and OG&E employees, respectively, and the grant date fair value for such units granted was $31.03.

Restricted Stock Units

Under the Stock Incentive Plan, OGE Energy has issued restricted stock units to certain existing non-officer employees as well as other executives upon hire to attract and retain individuals to be competitive in the marketplace, and as of the 2019 grant cycle, restricted stock units are granted in lieu of performance units based on earnings per share. The restricted stock units vest primarily in a three-year award cycle (i.e., three-year cliff vesting period). Prior to vesting, each restricted stock unit is subject to forfeiture if the recipient ceases to render substantial services to OGE Energy or a subsidiary. These restricted stock units may not be sold, assigned, transferred or pledged and are subject to a risk of forfeiture.

The fair value of the restricted stock units was based on the closing market price of OGE Energy's common stock on the grant date. Compensation expense for the restricted stock units is a fixed amount determined at the grant date fair value and is recognized as services are rendered by employees over a primarily three-year vesting period. Also, for those restricted stock units that vest in one-third annual increments over a three-year cycle, OGE Energy treats its restricted stock units as multiple separate awards by recording compensation expense separately for each tranche whereby a substantial portion of the expense is recognized in the earlier years in the requisite service period.

Dividends will only be paid on restricted stock unit awards that vest; therefore, only the present value of dividends expected to vest are included in the fair value calculations. The expected life of the restricted stock units is based on the non-vested period since inception of the primarily three-year award cycle. There are no post-vesting restrictions related to OGE Energy's restricted stock units. The following table presents the number of restricted stock units granted and the grant date fair value.


	OGE Energy						OG&E
	2020		2019		2018		2020		2019		2018
Restricted stock units granted	67,193		75,929		826		22,665		26,141		—
Fair value of restricted stock units granted	$	43.69	$	41.71	$	36.28	$	43.69	$	41.63	$	—

Performance Units and Restricted Stock Units Activity

The following tables present a summary of the activity for the Registrants' performance units and restricted stock units for the year ended December 31, 2020.


OGE Energy	Performance Units								Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
(Dollars in millions)	Number of Units		Aggregate Intrinsic Value		Number of Units		Aggregate Intrinsic Value		Number of Shares	Aggregate Intrinsic Value
Units/shares outstanding at 12/31/19	664,817				155,171				72,880
Granted	201,552	(A)			—				67,193

Converted	(222,163)	(B)	$	11.5	(74,053)	(B)	$	6.6	N/A
Vested	N/A				N/A				(2,608)	$	(0.1)
Forfeited	(31,944)				(2,116)				(12,546)
Units/shares outstanding at 12/31/20	612,262		$	5.4	79,002		$	2.7	124,919	$	4.0
Units/shares fully vested at 12/31/20	236,990		$	5.4	79,002		$	2.7	1,752	$	0.1


OG&E	Performance Units								Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
(Dollars in millions)	Number of Units		Aggregate Intrinsic Value		Number of Units		Aggregate Intrinsic Value		Number of Shares		Aggregate Intrinsic Value
Units/shares outstanding at 12/31/19	227,679				53,977				25,005
Granted	67,975	(A)			—				22,665
Converted	(77,799)	(B)	$	4.0	(25,931)	(B)	$	2.3	N/A
Vested	N/A				N/A				(1,113)		$	—
Forfeited	(28,985)				(1,969)				(11,100)
Employee migration	(6,507)	(C)			(842)	(C)			(1,327)	(C)
Units/shares outstanding at 12/31/20	182,363		$	1.7	25,235		$	0.8	34,130		$	1.1
Units/shares fully vested at 12/31/20	75,693		$	1.7	25,235		$	0.8	1,114		$	—

(A)For performance units, this represents the target number of performance units granted. Actual number of performance units earned, if any, is dependent upon performance and may range from zero percent to 200 percent of the target.

(B)These amounts represent performance units that vested at December 31, 2019 which were settled in March 2020.

(C)Due to certain employees transferring between OG&E and OGE Energy.

The following tables present a summary of the activity for the Registrants' non-vested performance units and restricted stock units for the year ended December 31, 2020.


OGE Energy	Performance Units							Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
	Number of Units		Weighted-Average Grant Date Fair Value		Number of Units	Weighted-Average Grant Date Fair Value		Number of Shares	Weighted-Average Grant Date Fair Value
Units/shares non-vested at 12/31/19	442,654		$	41.43	81,118	$	31.03	72,880	$	41.66
Granted	201,552	(A)	$	38.03	—	$	—	67,193	$	43.69

Vested	(236,990)		$	36.86	(79,002)	$	31.03	(2,608)	$	40.30
Forfeited	(31,944)		$	41.15	(2,116)	$	31.03	(12,546)	$	42.60
Units/shares non-vested at 12/31/20	375,272		$	42.51	—	$	—	124,919	$	42.69


OG&E	Performance Units								Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
	Number of Units		Weighted-Average Grant Date Fair Value		Number of Units		Weighted-Average Grant Date Fair Value		Number of Shares		Weighted-Average Grant Date Fair Value
Units/shares non-vested at 12/31/19	149,880		$	41.31	28,046		$	31.03	25,005		$	41.62
Granted	67,975	(A)	$	38.03	—		$	—	22,665		$	43.69
Vested	(75,693)		$	36.86	(25,235)		$	31.03	(1,113)		$	40.59
Forfeited	(28,985)		$	41.12	(1,969)		$	31.03	(11,100)		$	42.60
Employee migration	(6,507)	(B)	$	40.26	(842)	(B)	$	31.03	(1,327)	(B)	$	42.76
Units/shares non-vested at 12/31/20	106,670		$	42.49	—		$	—	34,130		$	42.67

(B)Due to certain employees transferring between OG&E and OGE Energy.

Fair Value of Vested Performance Units and Restricted Stock Units

The following table presents a summary of the Registrants' fair value for vested performance units and restricted stock units.


	OGE Energy						OG&E
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018
Performance units:
Total shareholder return	$	8.7	$	9.3	$	5.9	$	2.8	$	3.2	$	2.1
Earnings per share	$	2.5	$	5.2	$	4.9	$	0.8	$	0.9	$	1.7
Restricted stock units	$	0.1	$	0.1	$	0.1	$	0.1	$	—	$	—

Unrecognized Compensation Cost

The following table presents a summary of the Registrants' unrecognized compensation cost for non-vested performance units and restricted stock units and the weighted-average periods over which the compensation cost is expected to be recognized.


	OGE Energy			OG&E
December 31, 2020	Unrecognized Compensation Cost (In millions)		Weighted Average to be Recognized (In years)	Unrecognized Compensation Cost (In millions)		Weighted Average to be Recognized (In years)

Performance units - total shareholder return	$	7.1	1.62	$	1.8	1.64


Restricted stock units	1.6		1.65	0.4		1.68
Total unrecognized compensation cost	$	8.7		$	2.2

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Taxes [Abstract]

Income Tax Disclosure [Text Block]

Income Taxes

Income Tax Expense (Benefit)

The following table presents the components of income tax expense (benefit).


	OGE Energy						OG&E
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018
Provision (benefit) for current income taxes:
Federal	$	8.4	$	(6.4)	$	(1.9)	$	(3.8)	$	(7.9)	$	(12.4)
State	0.5		5.1		(4.4)		(0.6)		4.1		(4.1)
Total provision (benefit) for current income taxes	8.9		(1.3)		(6.3)		(4.4)		(3.8)		(16.5)
Provision (benefit) for deferred income taxes, net:
Federal	(105.2)		48.5		74.7		45.7		37.7		53.7
State	(31.1)		(17.4)		3.7		(6.6)		(13.8)		2.7
Total provision (benefit) for deferred income taxes, net	(136.3)		31.1		78.4		39.1		23.9		56.4
Deferred federal investment tax credits, net	—		—		0.1		—		—		0.1
Total income tax expense (benefit)	$	(127.4)	$	29.8	$	72.2	$	34.7	$	20.1	$	40.0

OGE Energy files consolidated income tax returns in the U.S. federal jurisdiction and various state jurisdictions. OG&E is a part of the consolidated income tax return of OGE Energy. With few exceptions, the Registrants are no longer subject to U.S. federal tax or state and local examinations by tax authorities for years prior to 2017. Income taxes are generally allocated to each company in the affiliated group, including OG&E, based on its stand-alone taxable income or loss. Federal investment tax credits previously claimed on electric utility property have been deferred and will be amortized to income over the life of the related property. Additionally, OG&E earns federal tax credits associated with production from its wind facilities. Oklahoma production and investment state tax credits are also earned on investments in electric and solar generating facilities which further reduce OG&E's effective tax rate.

The following table presents a reconciliation of the statutory tax rates to the effective income tax rate.


	OGE Energy						OG&E
Year Ended December 31	2020		2019		2018		2020		2019		2018
Statutory federal tax rate	21.0	%	21.0	%	21.0	%	21.0	%	21.0	%	21.0	%
Impairment of OGE Energy's investment in Enable (A)	31.6		—		—		—		—		—
Remeasurement of state deferred tax liabilities	0.9		(0.8)		(0.4)		—		—		—

Executive compensation limitation	0.2		0.2		0.2		—		—		—
Other	0.1		(0.7)		0.4		0.1		(0.6)		(0.1)
Federal renewable energy credit (B)	(5.0)		(6.0)		(5.1)		(5.4)		(7.6)		(6.9)
Amortization of net unfunded deferred taxes	(4.4)		(4.5)		(2.1)		(4.8)		(5.6)		(2.9)
State income taxes, net of federal income tax benefit	(1.4)		(1.2)		0.4		(1.6)		(1.8)		(0.2)
Stock-based compensation	(0.3)		(1.2)		—		—		—		—
401(k) dividends	(0.4)		(0.4)		(0.3)		—		—		—
Federal deferred tax revaluation	—		—		0.4		—		—		—

Effective income tax rate	42.3	%	6.4	%	14.5	%	9.3	%	5.4	%	10.9	%

(A)As further discussed in Note 5, OGE Energy recorded a $780.0 million impairment on its investment in Enable in March 2020, which resulted in a tax benefit being recorded that caused a significant variance to the effective tax rate as compared to the prior year. This variance has been presented in the table as a single line item in order to facilitate comparability of other components of the effective tax rate.

(B)Represents credits primarily associated with the production from OG&E's wind farms.

The deferred tax provisions are recognized as costs in the ratemaking process by the commissions having jurisdiction over the rates charged by OG&E. The following table presents the components of Deferred Income Taxes at December 31, 2020 and 2019.
















	OGE Energy				OG&E
December 31 (In millions)	2020		2019		2020		2019
Deferred income tax liabilities, net:
Accelerated depreciation and other property related differences	$	1,721.2	$	1,656.8	$	1,721.2	$	1,656.8

Investment in Enable	302.6		478.2		—		—
Regulatory assets	52.3		28.4		52.3		28.4
Pension Plan	3.9		4.1		27.4		24.5
Bond redemption-unamortized costs	2.0		2.2		2.0		2.2
Derivative instruments	1.7		1.6		—		—


Federal tax credits	(236.6)		(238.0)		(236.6)		(238.0)
Income taxes recoverable from customers, net	(221.8)		(229.9)		(221.8)		(229.9)
State tax credits	(204.4)		(185.8)		(189.0)		(170.8)
Regulatory liabilities	(81.0)		(68.1)		(81.0)		(68.1)
Postretirement medical and life insurance benefits	(22.4)		(23.3)		(15.3)		(16.0)
Asset retirement obligations	(20.3)		(19.2)		(20.3)		(19.2)
Net operating losses	(12.0)		(16.6)		(1.4)		(5.7)
Accrued liabilities	(9.6)		(10.7)		(5.2)		(4.3)
Deferred federal investment tax credits	(2.7)		(1.8)		(2.7)		(1.8)
Accrued vacation	(2.2)		(2.1)		(1.6)		(1.6)
Other	(1.4)		0.4		(6.5)		(4.7)
Uncollectible accounts	(0.7)		(0.4)		(0.7)		(0.4)

Total deferred income tax liabilities, net	$	1,268.6	$	1,375.8	$	1,020.8	$	951.4

As of December 31, 2020, the Registrants have classified $17.6 million of unrecognized tax benefits as a reduction of deferred tax assets recorded. Management is currently unaware of any issues under review that could result in significant additional payments, accruals or other material deviation from this amount.

The following table presents a reconciliation of the Registrants' total gross unrecognized tax benefits as of the years ended December 31, 2020, 2019 and 2018.


(In millions)	2020		2019		2018
Balance at January 1	$	20.7	$	20.7	$	20.7
Tax positions related to current year:
Additions	1.2		—		—


Balance at December 31	$	21.9	$	20.7	$	20.7

As of December 31, 2020, 2019 and 2018, there were $17.6 million, $16.4 million and $16.4 million, respectively, of unrecognized tax benefits that, if recognized, would affect the annual effective tax rate.

Where applicable, the Registrants classify income tax-related interest and penalties as interest expense and other expense, respectively. During the year ended December 31, 2020, there were no income tax-related interest or penalties recorded with regard to uncertain tax positions.

The Registrants recognize tax benefits from an uncertain tax position only if it is more likely than not the tax position will be sustained on examination by taxing authorities based on the technical merits of the position. The tax benefits in the financial statements from such positions are then measured based on the largest benefit that has a greater than 50 percent likelihood of being realized on settlement. As a result of those measurements, in September 2020, the Registrants recorded an additional reserve for certain federal research and development credits in the amount of $1.2 million.

The Registrants sustained federal and state tax operating losses through 2012 caused primarily by bonus depreciation and other book versus tax temporary differences. Federal net operating losses generated during those years have been fully utilized. State operating losses are being carried forward for utilization in future years. In addition to the tax operating losses, the Registrants were unable to utilize the various tax credits that were generated during those years. These tax losses and credits are being carried as deferred tax assets and will be utilized in future periods. Under current law, the Registrants anticipate future taxable income will be sufficient to utilize remaining losses and credits before they begin to expire after 2020. The following table presents a summary of these carry forwards.


	OGE Energy				OG&E
(In millions)	Carry Forward Amount		Deferred Tax Asset		Carry Forward Amount		Deferred Tax Asset		Earliest Expiration Date

State operating loss	$	268.0	$	12.0	$	21.5	$	1.4	2030
Federal tax credits	$	236.6	$	236.6	$	236.6	$	236.6	2032
State tax credits:
Oklahoma investment tax credits	$	205.6	$	162.3	$	186.1	$	147.0	N/A
Oklahoma capital investment board credits	$	12.7	$	12.7	$	12.7	$	12.7	N/A
Oklahoma zero emission tax credits	$	37.2	$	29.3	$	37.2	$	29.3	2021
Louisiana inventory credits	$	0.2	$	0.1	$	—	$	—	2021

N/A - not applicable

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

Long-term Debt, Unclassified [Abstract]

Common Equity

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Common Equity

OGE Energy

Automatic Dividend Reinvestment and Stock Purchase Plan

OGE Energy issued no shares of common stock under its Automatic Dividend Reinvestment and Stock Purchase Plan in 2020. OGE Energy may, from time to time, issue shares under its Automatic Dividend Reinvestment and Stock Purchase Plan or purchase shares traded on the open market. At December 31, 2020, there were 4,774,442 shares of unissued common stock reserved for issuance under OGE Energy's Automatic Dividend Reinvestment and Stock Purchase Plan.

Earnings (Loss) Per Share

Basic earnings (loss) per share is calculated by dividing net income (loss) attributable to OGE Energy by the weighted average number of OGE Energy's common shares outstanding during the period. In the calculation of diluted earnings (loss) per share, weighted average shares outstanding are increased for additional shares that would be outstanding if potentially dilutive securities were converted to common stock. Potentially dilutive securities for OGE Energy consist of performance units and restricted stock units. The following table presents the calculation of basic and diluted earnings (loss) per share for OGE Energy.


(In millions except per share data)	2020		2019		2018
Net income (loss)	$	(173.7)	$	433.6	$	425.5
Average common shares outstanding:
Basic average common shares outstanding	200.1		200.1		199.7
Effect of dilutive securities:
Contingently issuable shares (performance and restricted stock units)	—		0.6		0.8
Diluted average common shares outstanding	200.1		200.7		200.5
Basic earnings (loss) per average common share	$	(0.87)	$	2.17	$	2.13
Diluted earnings (loss) per average common share	$	(0.87)	$	2.16	$	2.12
Anti-dilutive shares excluded from earnings per share calculation	0.3		—		—

Dividend Restrictions

OGE Energy's Certificate of Incorporation places restrictions on the amount of common stock dividends it can pay when preferred stock is outstanding. Before OGE Energy can pay any dividends on its common stock, the holders of any of its preferred stock that may be outstanding are entitled to receive their dividends at the respective rates as may be provided for the shares of their series. As there is no preferred stock outstanding, that restriction did not place any effective limit on OGE Energy's ability to pay dividends to its shareholders.

OGE Energy utilizes receipts from its equity investment in Enable and dividends from OG&E to pay dividends to its shareholders. Enable's partnership agreement requires that it distribute all "available cash," as defined as cash on hand at the end of a quarter after the payment of expenses and the establishment of cash reserves and cash on hand resulting from working capital borrowings made after the end of the quarter.

Pursuant to the leverage restriction in OGE Energy's revolving credit agreement, OGE Energy must maintain a percentage of debt to total capitalization at a level that does not exceed 65 percent. The payment of cash dividends indirectly results in an increase in the percentage of debt to total capitalization, which results in the restriction of approximately $815.0 million of OGE Energy's retained earnings from being paid out in dividends. Accordingly, approximately $1.7 billion of OGE Energy's retained earnings as of December 31, 2020 are unrestricted for the payment of dividends.

OG&E

There were no new shares of OG&E common stock issued in 2020, 2019 or 2018.

Dividend Restrictions

Pursuant to the Federal Power Act, OG&E is restricted from paying dividends from its capital accounts. Dividends are paid from retained earnings. Pursuant to the leverage restriction in OG&E's revolving credit agreement, OG&E must also maintain a percentage of debt to total capitalization at a level that does not exceed 65 percent. The payment of cash dividends indirectly results in an increase in the percentage of debt to total capitalization, which results in the restriction of approximately $842.7 million of OG&E's retained earnings from being paid out in dividends. Accordingly, approximately $2.1 billion of OG&E's retained earnings as of December 31, 2020 are unrestricted for the payment of dividends.

Long-Term Debt

12 Months Ended

Dec. 31, 2020

Long-Term Debt

A summary of the Registrants' long-term debt is included in the statements of capitalization. The Registrants have no long-term debt maturing in the next five years. At December 31, 2020, the Registrants were in compliance with all of their debt agreements.

The Registrants have previously incurred costs related to debt refinancing. Unamortized loss on reacquired debt is classified as a Non-Current Regulatory Asset in the balance sheets. Unamortized debt expense and unamortized premium and discount on long-term debt are classified as Long-Term Debt in the balance sheets and are being amortized over the life of the respective debt.

OG&E Industrial Authority Bonds

OG&E has tax-exempt pollution control bonds with optional redemption provisions that allow the holders to request repayment of the bonds on any business day. The following table presents information about these bonds, which can be tendered at the option of the holder during the next 12 months.


Series			Date Due	Amount
				(In millions)
0.28%	-	5.35%	Garfield Industrial Authority, January 1, 2025	$	47.0
0.33%	-	4.31%	Muskogee Industrial Authority, January 1, 2025	32.4
0.28%	-	5.35%	Muskogee Industrial Authority, June 1, 2027	56.0
Total (redeemable during next 12 months)				$	135.4

All of these bonds are subject to an optional tender at the request of the holders, at 100 percent of the principal amount, together with accrued and unpaid interest to the date of purchase. The bond holders, on any business day, can request repayment of the bond by delivering an irrevocable notice to the tender agent stating the principal amount of the bond, payment instructions for the purchase price and the business day the bond is to be purchased. The repayment option may only be exercised by the holder of a bond for the principal amount. When a tender notice has been received by the trustee, a third-party remarketing agent for the bonds will attempt to remarket any bonds tendered for purchase. This process occurs once per week. Since the original issuance of these series of bonds in 1995 and 1997, the remarketing agent has successfully remarketed all tendered bonds. If the remarketing agent is unable to remarket any such bonds, OG&E is obligated to repurchase such unremarketed bonds. As OG&E has both the intent and ability to refinance the bonds on a long-term basis and such ability is supported by an ability to consummate the refinancing, the bonds are classified as Long-Term Debt in the balance sheets. OG&E believes that it has sufficient liquidity to meet these obligations.

Issuance of Long-Term Debt

In April 2020, OG&E issued $300.0 million of 3.25 percent senior notes due April 1, 2030. The proceeds from the issuance were added to OG&E's general funds to be used for general corporate purposes, including to fund ongoing capital expenditures and working capital.

Short-Term Debt and Credit Facilities

12 Months Ended

Dec. 31, 2020

Short-term Debt [Abstract]

Short-Term Debt and Credit Facilities

The Registrants borrow on a short-term basis, as necessary, by the issuance of commercial paper and by borrowings under their revolving credit agreements. OGE Energy also borrows under term credit agreements maturing in one year or less, as necessary. As of December 31, 2020, OGE Energy had $95.0 million short-term debt as compared to $112.0 million short-term debt at December 31, 2019. At December 31, 2020, OG&E had $272.0 million in advances to OGE Energy compared to $304.8 million at December 31, 2019.

In April 2020, OGE Energy entered into a $75.0 million floating rate unsecured one-year term credit agreement and borrowed the full $75.0 million, in order to preserve financial flexibility in response to COVID-19. Advances under this agreement were used to refinance existing indebtedness and for working capital and general corporate purposes of OGE Energy. The term credit agreement contained substantially the same covenants as OGE Energy's existing $450.0 million revolving credit agreement. In September 2020, OGE Energy repaid the $75.0 million borrowed under the term credit agreement.

The following table presents information regarding the Registrants' revolving credit agreements at December 31, 2020.


	Aggregate		Amount		Weighted-Average
Entity	Commitment		Outstanding (A)		Interest Rate			Expiration
	(In millions)
OGE Energy (B)	$	450.0	$	95.0	0.25	%	(D)	March 8, 2024	(F)
OG&E (C)(E)	450.0		0.4		1.00	%	(D)	March 8, 2024	(F)
Total	$	900.0	$	95.4	0.25	%

(A)Includes direct borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit at December 31, 2020.

(B)This bank facility is available to back up OGE Energy's commercial paper borrowings and to provide revolving credit borrowings. This bank facility can also be used as a letter of credit facility.

(C)This bank facility is available to back up OG&E's commercial paper borrowings and to provide revolving credit borrowings. This bank facility can also be used as a letter of credit facility.

(D)Represents the weighted-average interest rate for the outstanding borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit.

(E)OG&E has an intercompany borrowing agreement with OGE Energy whereby OG&E has access to up to $350.0 million of OGE Energy's revolving credit amount. This agreement has a termination date of March 8, 2024. At December 31, 2020, there were no intercompany borrowings under this agreement.

(F)In March 2017, the Registrants entered into unsecured five-year revolving credit agreements totaling $900.0 million ($450.0 million for OGE Energy and $450.0 million for OG&E). Each of the revolving credit facilities contained an option, which could be exercised up to two times, to extend the term of the respective facility for an additional year. In March 2018, the Registrants each utilized one of those extensions to extend the maturity of their respective credit facility from March 8, 2022 to March 8, 2023. In January 2021, the Registrants each utilized the second of those extensions to extend the maturity of their respective credit facility from March 8, 2023 to March 8, 2024. Commitments of a single existing lender with respect to $50.0 million of OGE Energy's credit facility, however, were not extended and, unless the non-extending lender is replaced in accordance with the terms of the credit facility, such commitments will expire March 8, 2023. The non-extending lender is not party to the OG&E facility.

In January 2021, the Registrants each entered into an amendment to their revolving credit facilities which gives each of the Registrants the option of extending such commitments for up to two additional one-year periods. In addition, the amendment addresses the establishment of an alternative rate of interest upon the occurrence of certain events related to the phase out of LIBOR.

On February 24, 2021, OGE Energy entered into a commitment letter with Wells Fargo and certain of its affiliates whereby Wells Fargo committed to provide an unsecured term loan facility in the aggregate principal amount of $1.0 billion. While borrowing availability still exists within the Registrants' credit facilities, the $1.0 billion commitment in additional short-term financing is expected to provide additional liquidity to help cover the increased fuel and purchased power costs incurred by OG&E during the February 2021 unprecedented cold weather event. For further discussion, see "Item 9B. Other Information."

The Registrants' credit facilities each have a financial covenant requiring that the respective borrower maintain a maximum debt to capitalization ratio of 65 percent, as defined in each such facility. The Registrants' facilities each also contain covenants which restrict the respective borrower and certain of its subsidiaries in respect of, among other things, mergers and consolidations, sales of all or substantially all assets, incurrence of liens and transactions with affiliates. The Registrants' facilities are each subject to acceleration upon the occurrence of any default, including, among others, payment defaults on such facilities, breach of representations, warranties and covenants, acceleration of indebtedness (other than intercompany and non-recourse indebtedness) of $100.0 million or more in the aggregate, change of control (as defined in each such facility), nonpayment of uninsured judgments in excess of $100.0 million and the occurrence of certain Employee Retirement Income Security Act and bankruptcy events, subject where applicable to specified cure periods.

The Registrants' ability to access the commercial paper market could be adversely impacted by a credit ratings downgrade or major market disruptions. Pricing grids associated with the Registrants' credit facilities could cause annual fees and borrowing rates to increase if an adverse rating impact occurs. The impact of any future downgrade could include an increase in the costs of the Registrants' short-term borrowings, but a reduction in the Registrants' credit ratings would not result in any defaults or accelerations. Any future downgrade could also lead to higher long-term borrowing costs and, if below investment grade, would require the Registrants to post collateral or letters of credit.

OG&E must obtain regulatory approval from the FERC in order to borrow on a short-term basis. OG&E has the necessary regulatory approvals to incur up to $800.0 million in short-term borrowings at any one time for a two-year period beginning January 1, 2021 and ending December 31, 2022.

Retirement Plans and Postretirement Benefit Plans

12 Months Ended

Dec. 31, 2020

Retirement Plans and Postretirement Benefit Plans [Abstract]

Pension and Other Postretirement Benefits Disclosure [Text Block]

Retirement Plans and Postretirement Benefit Plans

OGE Energy sponsors defined benefit pension plans, 401(k) savings plans and other postretirement plans covering certain employees of the Registrants.

Pension Plan and Restoration of Retirement Income Plan

It is OGE Energy's policy to fund the Pension Plan on a current basis based on the net periodic pension expense as determined by OGE Energy's actuarial consultants. Such contributions are intended to provide not only for benefits attributed to service to date but also for those expected to be earned in the future. OGE Energy made a $20.0 million contribution to its Pension Plan in both 2020 and 2019, of which $10.0 million and $5.0 million was attributed to OG&E in 2020 and 2019, respectively. In January 2021, OGE Energy made a $40.0 million contribution to its Pension Plan and has not determined whether it will need to make any additional contributions to the Pension Plan in 2021. Any contribution to the Pension Plan during 2021 would be a discretionary contribution, anticipated to be in the form of cash, and is not required to satisfy the minimum regulatory funding requirement specified by the Employee Retirement Income Security Act of 1974, as amended. OGE Energy could be required to make additional contributions if the value of its pension trust and postretirement benefit plan trust assets are adversely impacted by a major market disruption in the future.

In accordance with ASC Topic 715, "Compensation - Retirement Benefits," a one-time settlement charge is required to be recorded by an organization when lump sum payments or other settlements that relieve the organization from the responsibility for the pension benefit obligation during the plan year exceed the service cost and interest cost components of the organization's net periodic pension cost. During 2020, 2019 and 2018, the Registrants experienced an increase in both the number of employees electing to retire and the amount of lump sum payments paid to such employees upon retirement, which resulted in the Registrants recording pension plan settlement charges as presented in the Pension Plan net periodic benefit cost table. The pension settlement charges did not require a cash outlay by the Registrants and did not increase total pension expense over time, as the charges were an acceleration of costs that otherwise would be recognized as pension expense in future periods.

OGE Energy provides a Restoration of Retirement Income Plan to those participants in OGE Energy's Pension Plan whose benefits are subject to certain limitations of the Code. Participants in the Restoration of Retirement Income Plan receive the same benefits that they would have received under OGE Energy's Pension Plan in the absence of limitations imposed by the federal tax laws. The Restoration of Retirement Income Plan is intended to be an unfunded plan.

OG&E's employees participate in OGE Energy's Pension Plan and Restoration of Retirement Income Plan.

Obligations and Funded Status

The details of the funded status of OGE Energy's Pension Plan, the Restoration of Retirement Income Plan and the postretirement benefit plans and the amounts included in the balance sheets for 2020 and 2019 are included in the following tables. These amounts have been recorded in Accrued Benefit Obligations with the offset in Accumulated Other Comprehensive Loss (except OG&E's portion, which is recorded as a regulatory asset as discussed in Note 1) in the balance sheets. The amounts in Accumulated Other Comprehensive Loss and those recorded as a regulatory asset represent a net periodic benefit cost to be recognized in the statements of income in future periods. The benefit obligation for OGE Energy's Pension Plan and the Restoration of Retirement Income Plan represents the projected benefit obligation, while the benefit obligation for the postretirement benefit plans represents the accumulated postretirement benefit obligation. The accumulated postretirement benefit obligation for OGE Energy's Pension Plan and Restoration of Retirement Income Plan differs from the projected benefit obligation in that the former includes no assumption about future compensation levels.


	OGE Energy								OG&E
	Pension Plan				Restoration of Retirement Income Plan				Pension Plan				Restoration of Retirement Income Plan
December 31 (In millions)	2020		2019		2020		2019		2020		2019		2020		2019
Change in benefit obligation
Beginning obligations	$	616.1	$	615.9	$	10.3	$	9.6	$	462.0	$	453.6	$	6.1	$	6.0
Service cost	13.2		12.9		0.8		0.5		9.2		9.0		0.1		0.2
Interest cost	17.0		20.7		0.2		0.4		12.6		15.6		0.1		0.2
Plan settlements	(42.8)		(83.1)		(5.3)		(1.2)		(33.5)		(45.6)		(4.5)		(0.9)
Plan amendments	—		—		—		0.3		—		—		—		—
Plan curtailments	—		—		0.2		—		—		—		—		—
Special termination benefits	7.6		—		—		—		5.1		—		—		—

Actuarial losses	57.7		64.3		1.6		0.7		41.0		42.1		1.2		0.6
Benefits paid	(14.2)		(14.6)		—		—		(12.3)		(12.7)		—		—
Ending obligations	$	654.6	$	616.1	$	7.8	$	10.3	$	484.1	$	462.0	$	3.0	$	6.1

Change in plans' assets
Beginning fair value	$	530.3	$	522.8	$	—	$	—	$	399.1	$	387.6	$	—	$	—
Actual return on plans' assets	77.0		85.2		—		—		57.0		64.8		—		—
Employer contributions	20.0		20.0		5.3		1.2		10.0		5.0		4.5		0.9
Plan settlements	(42.8)		(83.1)		(5.3)		(1.2)		(33.5)		(45.6)		(4.5)		(0.9)

Benefits paid	(14.2)		(14.6)		—		—		(12.3)		(12.7)		—		—
Ending fair value	$	570.3	$	530.3	$	—	$	—	$	420.3	$	399.1	$	—	$	—
Funded status at end of year	$	(84.3)	$	(85.8)	$	(7.8)	$	(10.3)	$	(63.8)	$	(62.9)	$	(3.0)	$	(6.1)
Accumulated postretirement benefit obligation	$	610.8	$	563.3	$	6.9	$	8.1	$	454.7	$	425.8	$	2.9	$	4.8

For the year ended December 31, 2020, Pension Plan actuarial losses were primarily due to movement in the discount rate, special termination benefits due to a voluntary retirement program offered by OGE Energy and more retirements and terminations than expected which are expected to accelerate lump sum payments in 2021. These losses were partially offset by gains from lowering the interest crediting rate and plan mortality assumptions.


	OGE Energy				OG&E
	Postretirement Benefit Plans				Postretirement Benefit Plans
December 31 (In millions)	2020		2019		2020		2019
Change in benefit obligation
Beginning obligations	$	136.5	$	135.8	$	104.7	$	104.8
Service cost	0.2		0.2		0.2		0.2
Interest cost	4.2		5.6		3.2		4.3

Plan curtailments	4.0		—		3.1		—
Participants' contributions	3.3		4.1		2.4		3.0
Actuarial losses	7.3		2.9		4.5		2.2
Benefits paid	(11.0)		(12.1)		(8.6)		(9.8)
Ending obligations	$	144.5	$	136.5	$	109.5	$	104.7

Change in plans' assets
Beginning fair value	$	47.0	$	45.3	$	41.9	$	40.6
Actual return on plans' assets	1.2		4.6		1.1		4.0
Employer contributions	7.1		5.1		5.9		4.1

Participants' contributions	3.3		4.1		2.4		3.0
Benefits paid	(11.0)		(12.1)		(8.6)		(9.8)
Ending fair value	$	47.6	$	47.0	$	42.7	$	41.9
Funded status at end of year	$	(96.9)	$	(89.5)	$	(66.8)	$	(62.8)

Special termination benefits and curtailment loss for the year ended December 31, 2020 are related to a voluntary retirement program offered by OGE Energy in the fourth quarter of 2020. A curtailment gain or loss is required when the expected future services or benefits in a benefit plan are significantly reduced or eliminated.

Net Periodic Benefit Cost

The following tables present the net periodic benefit cost components, before consideration of capitalized amounts, of OGE Energy's Pension Plan, Restoration of Retirement Income Plan and postretirement benefit plans that are included in the financial statements. Service cost is presented within Other Operation and Maintenance, and the remaining net period benefit cost components as listed in the following tables are presented within Other Net Periodic Benefit Income (Expense) in the statements of income. OG&E recovers specific amounts of pension and postretirement medical costs in rates approved in its Oklahoma rate reviews. In accordance with approved orders, OG&E defers the difference between actual pension and postretirement medical expenses and the amount approved in its last Oklahoma rate review as a regulatory asset or regulatory liability. These amounts have been recorded in the Pension tracker in the regulatory assets and liabilities table in Note 1 and within Other Net Periodic Benefit Income (Expense) in the statements of income.


	OGE Energy												OG&E
	Pension Plan						Restoration of Retirement Income Plan						Pension Plan						Restoration of Retirement Income Plan
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018		2020		2019		2018		2020		2019		2018
Service cost	$	13.2	$	12.9	$	14.9	$	0.8	$	0.5	$	0.4	$	9.2	$	9.0	$	9.8	$	0.1	$	0.2	$	0.2
Interest cost	17.0		20.7		23.8		0.2		0.4		0.3		12.6		15.6		17.6		0.1		0.2		0.2
Expected return on plan assets	(37.6)		(36.1)		(44.1)		—		—		—		(27.9)		(27.6)		(33.1)		—		—		—

Amortization of net loss	17.1		17.3		16.2		0.5		0.5		0.7		12.1		12.9		12.1		0.4		0.3		0.5
Plan curtailments	—		—		—		0.2		—		—		—		—		—		—		—		—
Special termination benefits	7.6		—		—		—		—		—		5.1		—		—		—		—		—
Amortization of unrecognized prior service cost (A)	—		—		—		—		—		0.1		—		—		—		—		—		—
Settlement cost	14.1		27.6		25.1		2.7		0.5		1.0		11.4		16.4		19.4		2.4		0.5		0.4
Total net periodic benefit cost	31.4		42.4		35.9		4.4		1.9		2.5		22.5		26.3		25.8		3.0		1.2		1.3
Less: Amount paid by unconsolidated affiliates (B)	2.0		2.9		2.5		0.1		0.1		0.1
Plus: Amount allocated from OGE Energy (B)													5.9		4.5		5.7		1.3		0.5		1.2
Net periodic benefit cost	$	29.4	$	39.5	$	33.4	$	4.3	$	1.8	$	2.4	$	28.4	$	30.8	$	31.5	$	4.3	$	1.7	$	2.5

(A)Unamortized prior service cost is amortized on a straight-line basis over the average remaining service period to the first eligibility age of participants who are expected to receive a benefit and are active at the date of the plan amendment.

(B)"Amount paid by unconsolidated affiliates" is only applicable to OGE Energy. "Amount allocated from OGE Energy" is only applicable to OG&E.

In addition to the net periodic benefit cost amounts recognized, as presented in the table above, for the Pension and Restoration of Retirement Income Plans in 2020, 2019 and 2018, the Registrants recognized the following:



Year Ended December 31 (In millions)	2020		2019		2018
Decrease of pension expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	(13.8)	$	(16.1)	$	(14.1)
Deferral of pension expense related to pension settlement, curtailment and special termination benefits charges:
Oklahoma jurisdiction (A)	$	21.6	$	17.9	$	22.1
Arkansas jurisdiction (A)	$	2.0	$	1.7	$	2.1

(A) Included in the pension regulatory asset or liability in each jurisdiction, as indicated in the regulatory assets and liabilities table in Note 1.


	OGE Energy						OG&E
	Postretirement Benefit Plans						Postretirement Benefit Plans
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018
Service cost	$	0.2	$	0.2	$	0.3	$	0.2	$	0.2	$	0.2
Interest cost	4.2		5.6		5.4		3.2		4.3		4.2
Expected return on plan assets	(1.8)		(1.9)		(2.0)		(1.7)		(1.7)		(1.8)
Amortization of net loss	2.0		2.0		3.8		2.1		2.1		3.8
Plan curtailments	1.5		—		—		1.3		—		—
Amortization of unrecognized prior service cost (A)	(8.4)		(8.4)		(8.4)		(6.1)		(6.1)		(6.1)
Total net periodic benefit cost	(2.3)		(2.5)		(0.9)		(1.0)		(1.2)		0.3
Less: Amount paid by unconsolidated affiliates (B)	(0.7)		(0.6)		(0.5)
Plus: Amount allocated from OGE Energy (B)							(0.5)		(0.6)		(0.7)
Net periodic benefit cost	$	(1.6)	$	(1.9)	$	(0.4)	$	(1.5)	$	(1.8)	$	(0.4)

(A) Unamortized prior service cost is amortized on a straight-line basis over the average remaining service period to the first eligibility age of participants who are expected to receive a benefit and are active at the date of the plan amendment.

(B) "Amount paid by unconsolidated affiliates" is only applicable to OGE Energy. "Amount allocated from OGE Energy" is only applicable to OG&E.

In addition to the net periodic benefit income amounts recognized, as presented in the table above, for the postretirement benefit plans in 2020, 2019 and 2018, the Registrants recognized the following:


Year Ended December 31 (In millions)	2020		2019		2018
Increase of postretirement expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	0.2	$	1.0	$	4.4
Deferral of postretirement expense related to postretirement plan curtailment charges:
Oklahoma jurisdiction (A)	$	1.4	$	—	$	—
Arkansas jurisdiction (A)	$	0.1	$	—	$	—

(A) Included in the pension regulatory asset or liability in each jurisdiction, as indicated in the regulatory assets and liabilities table in Note 1.


	OGE Energy						OG&E
(In millions)	2020		2019		2018		2020		2019		2018
Capitalized portion of net periodic pension benefit cost	$	3.8	$	3.6	$	3.8	$	3.1	$	3.0	$	3.2
Capitalized portion of net periodic postretirement benefit cost	$	0.2	$	0.2	$	0.2	$	0.1	$	0.1	$	0.1

Rate Assumptions


	Pension Plan and Restoration of Retirement Income Plan						Postretirement Benefit Plans
Year Ended December 31	2020		2019		2018		2020		2019		2018
Assumptions to determine benefit obligations:
Discount rate	2.30	%	3.15	%	4.20	%	2.45	%	3.25	%	4.30	%
Rate of compensation increase	4.20	%	4.20	%	4.20	%	N/A		N/A		N/A
Interest crediting rate	3.50	%	4.00	%	4.00	%	N/A		N/A		N/A




Assumptions to determine net periodic benefit cost:
Discount rate	2.88	%	3.63	%	3.73	%	3.25	%	4.30	%	3.70	%
Expected return on plan assets	7.50	%	7.50	%	7.50	%	4.00	%	4.00	%	4.00	%
Rate of compensation increase	4.20	%	4.20	%	4.20	%	N/A		N/A		N/A
Interest crediting rate	4.00	%	4.00	%	4.00	%	N/A		N/A		N/A

N/A - not applicable

The discount rate used to compute the present value of plan liabilities is based generally on rates of high-grade corporate bonds with maturities similar to the average period over which benefits will be paid. The discount rate used to determine net benefit cost for the current year is the same discount rate used to determine the benefit obligation as of the previous year's balance sheet date, unless a plan settlement occurs during the current year that requires an updated discount rate for net periodic cost measurement. For 2020 and 2019, the Pension Plan discount rates used to determine net periodic benefit cost are disclosed on a weighted-average basis.

The overall expected rate of return on plan assets assumption is used in determining net periodic benefit cost due to recent returns on OGE Energy's long-term investment portfolio. The rate of return on plan assets assumption is the average long-term rate of earnings expected on the funds currently invested and to be invested for the purpose of providing benefits specified by the Pension Plan or postretirement benefit plans. This assumption is reexamined at least annually and updated as necessary. The rate of return on plan assets assumption reflects a combination of historical return analysis, forward-looking return expectations and the plans' current and expected asset allocation.

The assumed health care cost trend rates have a significant effect on the amounts reported for postretirement medical benefit plans. Future health care cost trend rates are assumed to be 6.75 percent in 2021 with the rates trending downward to 4.50 percent by 2030.

Pension Plan

Pension Plan Investments, Policies and Strategies

The Pension Plan assets are held in a trust which follows an investment policy and strategy designed to reduce the funded status volatility of the Plan by utilizing liability driven investing. The purpose of liability-driven investing is to structure the asset portfolio to more closely resemble the pension liability and thereby more effectively hedge against changes in the liability. The investment policy follows a glide path approach that shifts a higher portfolio weighting to fixed income as the Plan's funded status increases. The following table presents the targeted fixed income and equity allocations at different funded status levels.


Projected Benefit Obligation Funded Status Thresholds	<90%	95%	100%	105%	110%	115%	120%
Fixed income	50%	58%	65%	73%	80%	85%	90%
Equity	50%	42%	35%	27%	20%	15%	10%
Total	100%	100%	100%	100%	100%	100%	100%

Within the portfolio's overall allocation to equities, the funds are allocated according to the guidelines in the following table.


Asset Class	Target Allocation	Minimum	Maximum
Domestic Large Cap Equity	40%	35%	60%
Domestic Mid-Cap Equity	15%	5%	25%
Domestic Small-Cap Equity	25%	5%	30%
International Equity	20%	10%	30%

OGE Energy has retained an investment consultant responsible for the general investment oversight, analysis, monitoring investment guideline compliance and providing quarterly reports to certain of the Registrants' members and OGE Energy's Investment Committee. The various investment managers used by the trust operate within the general operating objectives as established in the investment policy and within the specific guidelines established for each investment manager's respective portfolio.

The portfolio is rebalanced at least on an annual basis to bring the asset allocations of various managers in line with the target asset allocation listed above. More frequent rebalancing may occur if there are dramatic price movements in the financial markets which may cause the trust's exposure to any asset class to exceed or fall below the established allowable guidelines.

To evaluate the progress of the portfolio, investment performance is reviewed quarterly. It is, however, expected that performance goals will be met over a full market cycle, normally defined as a three- to five-year period. Analysis of performance is within the context of the prevailing investment environment and the advisors' investment style. The goal of the trust is to provide a rate of return consistently from three percent to five percent over the rate of inflation (as measured by the national Consumer Price Index) on a fee adjusted basis over a typical market cycle of no less than three years and no more than five years. Each investment manager is expected to outperform its respective benchmark.

The following table presents a list of each asset class utilized with appropriate comparative benchmark(s) each manager is evaluated against and the focus of the asset class.


Asset Class	Comparative Benchmark(s)	Focus of Asset Class
Active Duration Fixed Income (A)(B)	Bloomberg Barclays Aggregate	l Maximize risk-adjusted performance while providing long bond exposure managed according to the manager's forecast on interest rates. l All invested assets must reach at or above Baa3 or BBB- investment grade. l Limited five percent exposure to any single issuer, except the U.S. Government or affiliates.

Long Duration Fixed Income (A)(B)	Duration blended Barclays Long Government/Credit & Barclays Universal	l Maximize risk-adjusted performance. l At least 75 percent of invested assets much reach at or above Baaa3 or BBB- investment grade. l Limited five percent exposure to any single issuer, except the U.S. Government or affiliates. l May invest up to 10 percent of the market value in convertible bonds as long as quality guidelines are met. l May invest up to 15 percent of the market value in private placement, including 144A securities with or without registration rights and allow for futures to be traded in the portfolio.
Equity Index (B)(C)	Standard & Poor's 500 Index	l Focus on replicating the performance of the S&P 500 Index.


Mid-Cap Equity (B)(C)	Russell Midcap Index Russell Midcap Value Index	l Focus on undervalued stocks expected to earn average return and pay out higher than average dividends. l Invest in companies with market capitalizations lower than average company on public exchanges: l Price/earnings ratio at or near referenced index; l Small dividend yield and return on equity at or near referenced index; and l Earnings per share growth rate at or near referenced index.

Small-Cap Equity (B)(C)	Russell 2000 Index Russell 2000 Value Index


International Equity (D)			Morgan Stanley Capital International ACWI ex-U.S.			l Invest in non-dollar denominated equity securities. l Diversify the overall trust investments.

(A)Investment grades are by Moody's Investors Service, S&P Global Ratings or Fitch Ratings.

(B)The purchase of any of OGE Energy's equity, debt or other securities is prohibited.

(C)No more than five percent can be invested in any one stock at the time of purchase and no more than 10 percent after accounting for price appreciation. Options or financial futures may not be purchased unless prior approval from OGE Energy's Investment Committee is received. The purchase of securities on margin, securities lending, private placement purchases and venture capital purchases are prohibited. The aggregate positions in any company may not exceed one percent of the fair market value of its outstanding stock.

(D)The manager of this asset class is required to operate under certain restrictions including regional constraints, diversification requirements and percentage of U.S. securities. All securities are freely traded on a recognized stock exchange, and there are no over-the-counter derivatives. The following investment categories are excluded: options (other than traded currency options), commodities, futures (other than currency futures or currency hedging), short sales/margin purchases, private placements, unlisted securities and real estate (but not real estate shares).

Pension Plan Investments

The following tables present the Pension Plan's investments that are measured at fair value on a recurring basis at December 31, 2020 and 2019. There were no Level 3 investments held by the Pension Plan at December 31, 2020 and 2019.


(In millions)	December 31, 2020		Level 1		Level 2		Net Asset Value (A)
Common stocks	$	252.3	$	252.3	$	—	$	—
U.S. Treasury notes and bonds (B)	134.3		134.3		—		—
Mortgage- and asset-backed securities	29.3		—		29.3		—
Corporate fixed income and other securities	116.6		—		116.6		—
Commingled fund (C)	25.4		—		—		25.4
Foreign government bonds	4.6		—		4.6		—
U.S. municipal bonds	1.8		—		1.8		—

Money market fund	8.8		—		—		8.8
Mutual fund	9.2		9.2		—		—
Preferred stocks	0.6		0.6		—		—
U.S. Treasury futures:


Cash collateral	0.7		0.7		—		—
Forward contracts:
Receivable (foreign currency)	0.1		—		0.1		—

Total Pension Plan investments	583.7		$	397.1	$	152.4	$	34.2
Receivable from broker for securities sold	0.2
Interest and dividends receivable	2.2
Payable to broker for securities purchased	(15.8)
Total OGE Energy Pension Plan assets	$	570.3
Pension Plan investments attributable to affiliates	(150.0)
Total OG&E Pension Plan assets	$	420.3

(A)GAAP allows the measurement of certain investments that do not have a readily determinable fair value at the net asset value. These investments do not consider the observability of inputs; therefore, they are not included within the fair value hierarchy.

(B)This category represents U.S. Treasury notes and bonds with a Moody's Investors Service rating of Aaa and Government Agency Bonds with a Moody's Investors Service rating of A1 or higher.

(C)This category represents units of participation in a commingled fund that primarily invested in stocks of international companies and emerging markets.


(In millions)	December 31, 2019		Level 1		Level 2		Net Asset Value (A)

Common stocks	$	202.0	$	202.0	$	—	$	—


U.S. Treasury notes and bonds (B)	134.8		134.8		—		—
Mortgage- and asset-backed securities	45.8		—		45.8		—


Corporate fixed income and other securities	130.5		—		130.5		—

Commingled fund (C)	23.9		—		—		23.9
Foreign government bonds	3.0		—		3.0		—
U.S. municipal bonds	1.1		—		1.1		—

Money market fund	2.4		—		—		2.4

Mutual fund	7.5		7.5		—		—
Preferred stocks	0.7		0.7		—		—
Futures:
U.S. Treasury futures (receivable)	22.9		—		22.9		—
U.S. Treasury futures (payable)	(10.9)		—		(10.9)		—
Cash collateral	0.6		0.6		—		—
Forward contracts:
Receivable (foreign currency)	0.1		—		0.1		—

Total Pension Plan investments	564.4		$	345.6	$	192.5	$	26.3

Interest and dividends receivable	2.4
Payable to broker for securities purchased	(36.5)
Total OGE Energy Pension Plan assets	$	530.3
Pension Plan investments attributable to affiliates	(131.2)
Total OG&E Pension Plan assets	$	399.1

(B)This category represents U.S. Treasury notes and bonds with a Moody's Investors Service rating of Aaa and Government Agency Bonds with a Moody's Investors Service rating of A1 or higher.

(C)This category represents units of participation in a commingled fund that primarily invested in stocks of international companies and emerging markets.

As defined in the fair value hierarchy, Level 1 inputs are quoted prices in active markets for identical unrestricted assets or liabilities that are accessible by the Pension Plan at the measurement date. Level 2 inputs are inputs other than quoted prices in active markets included within Level 1 that are either directly or indirectly observable at the reporting date for the asset or liability for substantially the full term of the asset or liability. Level 2 inputs include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active. Level 3 inputs are prices or valuation techniques for the asset or liability that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity). Unobservable inputs reflect the Plan's own assumptions about the assumptions that market participants would use in pricing the asset or liability (including assumptions about risk).

Expected Benefit Payments

The following table presents the benefit payments the Registrants expect to pay related to the Pension Plan and Restoration of Retirement Income Plan. These expected benefits are based on the same assumptions used to measure OGE Energy's benefit obligation at the end of the year and include benefits attributable to estimated future employee service.


(In millions)	OGE Energy		OG&E
2021	$	164.2	$	123.9
2022	$	43.3	$	33.1
2023	$	42.5	$	31.9
2024	$	44.2	$	32.3
2025	$	41.1	$	29.3
After 2025	$	203.6	$	141.1

Postretirement Benefit Plans

In addition to providing pension benefits, OGE Energy provides certain medical and life insurance benefits for eligible retired members. Regular, full-time, active employees hired prior to February 1, 2000 whose age and years of credited service total or exceed 80 or have attained at least age 55 with 10 or more years of service at the time of retirement are entitled to postretirement medical benefits, while employees hired on or after February 1, 2000 are not entitled to postretirement medical benefits. Eligible retirees must contribute such amount as OGE Energy specifies from time to time toward the cost of coverage for postretirement benefits. The benefits are subject to deductibles, co-payment provisions and other limitations. OG&E charges postretirement benefit costs to expense and includes an annual amount as a component of the cost-of-service in future ratemaking proceedings.

OGE Energy's contribution to the medical costs for pre-65 aged eligible retirees are fixed at the 2011 level, and OGE Energy covers future annual medical inflationary cost increases up to five percent. Increases in excess of five percent annually are covered by the pre-65 aged retiree in the form of premium increases. OGE Energy provides Medicare-eligible retirees and their Medicare-eligible spouses an annual fixed contribution to an OGE Energy-sponsored health reimbursement arrangement. Medicare-eligible retirees are able to purchase individual insurance policies supplemental to Medicare through a third-party administrator and use their health reimbursement arrangement funds for reimbursement of medical premiums and other eligible medical expenses.

Postretirement Plans Investments

The following tables present the postretirement benefit plans' investments that are measured at fair value on a recurring basis at December 31, 2020 and 2019. There were no Level 2 investments held by the postretirement benefit plans at December 31, 2020 and 2019.


(In millions)	December 31, 2020		Level 1		Level 3
Group retiree medical insurance contract	$	33.4	$	—	$	33.4

Mutual fund	10.8		10.8		—

Money market fund	3.4		3.4		—
Total OGE Energy plan investments	$	47.6	$	14.2	$	33.4
Plan investments attributable to affiliates	(4.9)
Total OG&E plan investments	$	42.7


(In millions)	December 31, 2019		Level 1		Level 3
Group retiree medical insurance contract	$	34.8	$	—	$	34.8

Mutual funds	10.9		10.9		—

Money market fund	1.2		1.2		—
Total OGE Energy plan investments	$	46.9	$	12.1	$	34.8
Plan investments attributable to affiliates	(5.0)
Total OG&E plan investments	$	41.9

The group retiree medical insurance contract invests in a pool of common stocks, bonds and money market accounts, of which a significant portion is comprised of mortgage-backed securities. The unobservable input included in the valuation of the contract includes the approach for determining the allocation of the postretirement benefit plans' pro-rata share of the total assets in the contract.

The following table presents a reconciliation of the postretirement benefit plans' investments that are measured at fair value on a recurring basis using significant unobservable inputs (Level 3).


Year Ended December 31 (In millions)	2020
Group retiree medical insurance contract:
Beginning balance	$	34.8
Claims paid	(3.7)
Investment fees	(0.1)
Interest income	0.8
Net unrealized gains related to instruments held at the reporting date	0.6
Dividend income	0.6
Realized gains	0.4
Ending balance	$	33.4

Medicare Prescription Drug, Improvement and Modernization Act of 2003

The Medicare Prescription Drug, Improvement and Modernization Act of 2003 expanded coverage for prescription drugs. The following table presents the gross benefit payments the Registrants expect to pay related to the postretirement benefit plans, including prescription drug benefits.


(In millions)	OGE Energy		OG&E
2021	$	11.9	$	9.4
2022	$	11.8	$	9.3
2023	$	11.4	$	8.9
2024	$	10.0	$	7.7
2025	$	9.5	$	7.3
After 2025	$	40.9	$	31.0

Post-Employment Benefit Plan

Disabled employees receiving benefits from OGE Energy's Group Long-Term Disability Plan are entitled to continue participating in OGE Energy's Medical Plan along with their dependents. The post-employment benefit obligation represents the actuarial present value of estimated future medical benefits that are attributed to employee service rendered prior to the date as of which such information is presented. The obligation also includes future medical benefits expected to be paid to current employees participating in the Group Long-Term Disability Plan and their dependents, as defined in OGE Energy's Medical Plan.

The post-employment benefit obligation is determined by an actuary on a basis similar to the accumulated postretirement benefit obligation. The estimated future medical benefits are projected to grow with expected future medical cost trend rates and are discounted for interest at the discount rate and for the probability that the participant will discontinue receiving benefits from OGE Energy's Group Long-Term Disability Plan due to death, recovery from disability or eligibility for retiree medical benefits. OGE Energy's post-employment benefit obligation was $2.2 million and $2.1 million at December 31, 2020 and 2019, respectively, of which $1.8 million and $1.7 million, respectively, was OG&E's portion of the obligation.

401(k) Plan

OGE Energy provides a 401(k) Plan, and each regular full-time employee of OGE Energy or a participating affiliate is eligible to participate in the 401(k) Plan immediately upon hire. All other employees of OGE Energy or a participating affiliate are eligible to become participants in the 401(k) Plan after completing one year of service as defined in the 401(k) Plan. Participants may contribute each pay period any whole percentage between two percent and 19 percent of their compensation, as defined in the 401(k) Plan, for that pay period. Participants who have reached age 50 before the close of a year are allowed to make additional contributions referred to as "Catch-Up Contributions," subject to certain limitations of the Code. Participants may designate, at their discretion, all or any portion of their contributions as: (i) a before-tax contribution under Section 401(k) of the Code subject to the limitations thereof, (ii) a contribution made on a non-Roth after-tax basis or (iii) a Roth contribution. The 401(k) Plan also includes an eligible automatic contribution arrangement and provides for a qualified default investment alternative consistent with the U.S. Department of Labor regulations. Participants may elect, in accordance with the 401(k) Plan procedures, to have their future salary deferral rate to be automatically increased annually on a date and in an amount as specified by the participant in such election. For employees hired or rehired on or after December 1, 2009, OGE Energy contributes to the 401(k) Plan, on behalf of each participant, 200 percent of the participant's contributions up to five percent of compensation.

No OGE Energy contributions are made with respect to a participant's Catch-Up Contributions, rollover contributions or with respect to a participant's contributions based on overtime payments, pay-in-lieu of overtime for exempt personnel, special lump-sum recognition awards and lump-sum merit awards included in compensation for determining the amount of participant contributions. Once made, OGE Energy's contribution may be directed to any available investment option in the 401(k) Plan. OGE Energy match contributions vest over a three-year period. After two years of service, participants become 20 percent vested in their OGE Energy contribution account and become fully vested on completing three years of service. In addition, participants fully vest when they are eligible for normal or early retirement under the Pension Plan requirements, in the event of their termination due to death or permanent disability or upon attainment of age 65 while employed by OGE Energy or its affiliates. OGE Energy contributed $18.2 million, $14.4 million and $13.2 million in 2020, 2019 and 2018, respectively, to the 401(k) Plan, of which $14.3 million, $11.0 million and $9.8 million, respectively, related to OG&E.

Deferred Compensation Plan

OGE Energy provides a nonqualified deferred compensation plan which is intended to be an unfunded plan. The plan's primary purpose is to provide a tax-deferred capital accumulation vehicle for a select group of management, highly compensated employees and non-employee members of OGE Energy's Board of Directors and to supplement such employees' 401(k) Plan contributions as well as offering this plan to be competitive in the marketplace.

Eligible employees who enroll in the plan have the following deferral options: (i) eligible employees may elect to defer up to a maximum of 70 percent of base salary and 100 percent of annual bonus awards or (ii) eligible employees may elect a deferral percentage of base salary and bonus awards based on the deferral percentage elected for a year under the 401(k) Plan with such deferrals to start when maximum deferrals to the qualified 401(k) Plan have been made because of limitations in that plan. Eligible directors who enroll in the plan may elect to defer up to a maximum of 100 percent of directors' meeting fees and annual retainers. OGE Energy matches employee (but not non-employee director) deferrals to make up for any match lost in the 401(k) Plan because of deferrals to the deferred compensation plan and to allow for a match that would have been made under the 401(k) Plan on that portion of either the first six percent of total compensation or the first five percent of total compensation, depending on prior participant elections, deferred that exceeds the limits allowed in the 401(k) Plan. Matching credits vest based on years of service, with full vesting after three years or, if earlier, on retirement, disability, death, a change in control of OGE Energy or termination of the plan. Deferrals, plus any OGE Energy match, are credited to a recordkeeping account in the participant's name. Earnings on the deferrals are indexed to the assumed investment funds selected by the participant. In 2020, those investment options included an OGE Energy Common Stock fund, whose value was determined based on the stock price of OGE Energy's Common Stock. OGE Energy accounts for the contributions related to its executive officers in this plan as Accrued Benefit Obligations and accounts for the contributions related to OGE Energy's directors in this plan as Other Deferred Credits and Other Liabilities in the balance sheets. The investment associated with these contributions is accounted for as Other Property and Investments in the balance sheets. The appreciation of these investments is accounted for as Other Income, and the increase in the liability under the plan is accounted for as Other Expense in the statements of income.

Supplemental Executive Retirement Plan

OGE Energy provides a supplemental executive retirement plan in order to attract and retain lateral hires or other executives designated by the Compensation Committee of OGE Energy's Board of Directors who may not otherwise qualify for a sufficient level of benefits under OGE Energy's Pension Plan and Restoration of Retirement Income Plan. The supplemental executive retirement plan is intended to be an unfunded plan and not subject to the benefit limitations of the Code. For the actuarial equivalence calculations, the supplemental executive retirement plan provides that (i) mortality rates shall be based on the unisex mortality table issued under Internal Revenue Service Notice 2018-02 for purposes of determining the minimum present value under Code Section 417(e)(3) for distributions with annuity starting dates that occur during stability periods beginning in the 2019 calendar year and (ii) the interest rate shall be five percent.

The entire disclosure for retirement benefits.

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Report of Business Segments

12 Months Ended

Dec. 31, 2020

Report of Business Segments

OGE Energy reports its operations in two business segments: (i) the electric utility segment, which is engaged in the generation, transmission, distribution and sale of electric energy and (ii) natural gas midstream operations segment. Other operations primarily includes the operations of the holding company. Intersegment revenues are recorded at prices comparable to those of unaffiliated customers and are affected by regulatory considerations. The following tables present the results of OGE Energy's business segments for the years ended December 31, 2020, 2019 and 2018.


2020	Electric Utility		Natural Gas Midstream Operations		Other Operations		Eliminations		Total
(In millions)
Operating revenues	$	2,122.3	$	—	$	—	$	—	$	2,122.3
Cost of sales	644.6		—		—		—		644.6
Other operation and maintenance	464.4		1.7		(3.3)		—		462.8
Depreciation and amortization	391.3		—		—		—		391.3
Taxes other than income	97.2		0.4		3.8		—		101.4
Operating income (loss)	524.8		(2.1)		(0.5)		—		522.2
Equity in losses of unconsolidated affiliates (A)	—		(668.0)		—		—		(668.0)
Other income (expense)	4.1		(2.9)		3.6		(1.6)		3.2
Interest expense	154.8		—		5.3		(1.6)		158.5
Income tax expense (benefit)	34.7		(158.0)		(4.1)		—		(127.4)
Net income (loss)	$	339.4	$	(515.0)	$	1.9	$	—	$	(173.7)
Investment in unconsolidated affiliates	$	—	$	374.3	$	23.1	$	—	$	397.4
Total assets	$	10,489.0	$	378.1	$	116.4	$	(264.7)	$	10,718.8
Capital expenditures	$	650.5	$	—	$	—	$	—	$	650.5

(A) In March 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Notes 5 and 7.


2019	Electric Utility		Natural Gas Midstream Operations		Other Operations		Eliminations		Total
(In millions)
Operating revenues	$	2,231.6	$	—	$	—	$	—	$	2,231.6
Cost of sales	786.9		—		—		—		786.9
Other operation and maintenance	492.5		2.8		(3.5)		—		491.8
Depreciation and amortization	355.0		—		—		—		355.0
Taxes other than income	89.5		0.4		3.7		—		93.6
Operating income (loss)	507.7		(3.2)		(0.2)		—		504.3
Equity in earnings of unconsolidated affiliates	—		113.9		—		—		113.9
Other income (expense)	3.1		(8.6)		2.2		(3.6)		(6.9)
Interest expense	140.5		—		11.0		(3.6)		147.9
Income tax expense (benefit)	20.1		20.7		(11.0)		—		29.8
Net income	$	350.2	$	81.4	$	2.0	$	—	$	433.6


Investment in unconsolidated affiliates	$	—	$	1,132.9	$	18.6	$	—	$	1,151.5
Total assets	$	10,076.6	$	1,135.4	$	107.0	$	(294.7)	$	11,024.3
Capital expenditures	$	635.5	$	—	$	—	$	—	$	635.5


2018	Electric Utility		Natural Gas Midstream Operations		Other Operations		Eliminations		Total
(In millions)
Operating revenues	$	2,270.3	$	—	$	—	$	—	$	2,270.3
Cost of sales	892.5		—		—		—		892.5
Other operation and maintenance	473.8		1.4		(0.6)		—		474.6
Depreciation and amortization	321.6		—		—		—		321.6
Taxes other than income	88.2		0.6		3.2		—		92.0
Operating income (loss)	494.2		(2.0)		(2.6)		—		489.6
Equity in earnings of unconsolidated affiliates	—		152.8		—		—		152.8
Other income (expense)	25.6		(4.9)		(3.4)		(6.0)		11.3
Interest expense	151.8		—		10.2		(6.0)		156.0
Income tax expense (benefit)	40.0		37.1		(4.9)		—		72.2
Net income (loss)	$	328.0	$	108.8	$	(11.3)	$	—	$	425.5


Investment in unconsolidated affiliates	$	—	$	1,166.6	$	10.9	$	—	$	1,177.5
Total assets	$	9,704.5	$	1,169.8	$	184.8	$	(310.5)	$	10,748.6
Capital expenditures	$	573.6	$	—	$	—	$	—	$	573.6

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies

Public Utility Regulatory Policy Act of 1978

OG&E had QF contracts with AES-Shady Point, Inc. and Oklahoma Cogeneration LLC, which expired in January and August 2019, respectively. For the 320 MW AES-Shady Point, Inc. QF contract and the 120 MW Oklahoma Cogeneration LLC QF contract, OG&E purchased 100 percent of the electricity generated by the qualified cogeneration facilities. In 2019, OG&E received approval from the OCC and APSC to acquire the plants from AES-Shady Point, Inc. and Oklahoma Cogeneration LLC.

For the years ended December 31, 2019 and 2018, OG&E made total payments to cogenerators of $14.7 million and $112.4 million, respectively, of which $7.4 million and $60.0 million, respectively, represented capacity payments. All payments for purchased power, including cogeneration, are included in the Registrants' statements of income as Cost of Sales.

Purchase Obligations and Commitments

The following table presents the Registrants' future purchase obligations and commitments estimated for the next five years.


(In millions)	2021		2022		2023		2024		2025		Total
Purchase obligations and commitments:
Minimum purchase commitments	$	72.5	$	50.4	$	50.4	$	36.7	$	25.9	$	235.9
Expected wind purchase commitments	55.2		55.6		56.0		56.6		56.9		280.3
Long-term service agreement commitments	2.4		2.4		7.9		35.1		31.2		79.0


Total purchase obligations and commitments	$	130.1	$	108.4	$	114.3	$	128.4	$	114.0	$	595.2

OG&E Minimum Purchase Commitments

OG&E has coal contracts for purchases through June 30, 2021, whereby OG&E has the right but not the obligation to purchase a defined quantity of coal. OG&E may also purchase coal through spot purchases on an as-needed basis. As a participant in the SPP Integrated Marketplace, OG&E purchases its natural gas supply through short-term agreements. OG&E relies on a combination of natural gas base load agreements and call agreements, whereby OG&E has the right but not the obligation to purchase a defined quantity of natural gas, combined with day and intra-day purchases to meet the demands of the SPP Integrated Marketplace.

OG&E has natural gas transportation service contracts with Enable, ONEOK, Inc. and Southern Star. The contracts with Enable end in May 2024 and December 2038; the contracts with ONEOK, Inc. end in March 2024 and August 2037; and the contract with Southern Star ends in June 2024. These transportation contracts grant Enable, ONEOK, Inc. and Southern Star the responsibility of delivering natural gas to OG&E's generating facilities.

OG&E Wind Purchase Commitments

The following table presents OG&E's wind power purchase contracts.

Company

Location

Original Term of Contract

Expiration of Contract

MWs

CPV Keenan

Woodward County, OK

20 years

2030

152.0

Edison Mission Energy

Dewey County, OK

20 years

2031

130.0

NextEra Energy

Blackwell, OK

20 years

2032

60.0

The following table presents a summary of OG&E's wind power purchases for the years ended December 31, 2020, 2019 and 2018.


Year Ended December 31 (In millions)	2020		2019		2018
CPV Keenan	$	27.5	$	27.2	$	27.0
Edison Mission Energy	22.8		23.1		21.7
NextEra Energy	7.0		7.4		6.8
FPL Energy (A)	—		—		2.1
Total wind power purchased	$	57.3	$	57.7	$	57.6

(A)OG&E's purchased power contract with FPL Energy for 50 MWs expired in 2018.

OG&E Long-Term Service Agreement Commitments

OG&E has a long-term parts and service maintenance contract for the upkeep of the McClain Plant. In May 2013, a new contract was signed that is expected to run for the earlier of 128,000 factored-fired hours or 4,800 factored-fired starts. In December 2015, the McClain Long-Term Service Agreement was amended to define the terms and conditions for the exchange of spare rotors between OG&E and General Electric International, Inc. Based on historical usage and current expectations for future usage, this contract is expected to run until 2033. The contract requires payments based on both a fixed and variable cost component, depending on how much the McClain Plant is used.

OG&E has a long-term parts and service maintenance contract for the upkeep of the Redbud Plant. In March 2013, the contract was amended to extend the contract coverage for an additional 24,000 factored-fired hours resulting in a maximum of the earlier of 144,000 factored-fired hours or 4,500 factored-fired starts. Based on historical usage and current expectations for future usage, this contract is expected to run until 2030. The contract requires payments based on both a fixed and variable cost component, depending on how much the Redbud Plant is used.

Environmental Laws and Regulations

The activities of the Registrants are subject to numerous stringent and complex federal, state and local laws and regulations governing environmental protection. These laws and regulations can change, restrict or otherwise impact the Registrants' business activities in many ways, including the handling or disposal of waste material, planning for future construction activities to avoid or mitigate harm to threatened or endangered species and requiring the installation and operation of emissions or pollution control equipment. Failure to comply with these laws and regulations could result in the assessment of administrative, civil and criminal penalties, the imposition of remedial requirements and the issuance of orders enjoining future operations. Management believes that all of the Registrants' operations are in substantial compliance with current federal, state and local environmental standards.

Environmental regulation can increase the cost of planning, design, initial installation and operation of OG&E's facilities. Management continues to evaluate its compliance with existing and proposed environmental legislation and regulations and implement appropriate environmental programs in a competitive market.

CO2 Emission Limits for Existing Generating Units

On January 19, 2021, the U.S. Court of Appeals vacated the EPA's latest effort to adopt CO2 emissions standards for existing coal-fired electric generating units, and the court remanded the matter to the EPA for further consideration. The decision was based on the court's conclusion that the Clean Air Act does not require the EPA to limit the standards to measures that can be applied at and to an existing unit. The time for seeking further judicial review of the decision does not expire until June 18, 2021, and the EPA has not announced how it plans to respond to the decision. The ultimate timing and impact of these standards on OG&E's operations cannot be determined with certainty at this time, although a requirement for significant reduction of CO2 emissions from existing fossil-fuel-fired power plants ultimately could result in significant additional compliance costs that would affect the Registrants' future financial position, results of operations and cash flows if such costs are not recovered through regulated rates.

Other

In the normal course of business, the Registrants are confronted with issues or events that may result in a contingent liability. These generally relate to lawsuits or claims made by third parties, including governmental agencies. When appropriate, management consults with legal counsel and other experts to assess the claim. If, in management's opinion, the Registrants have incurred a probable loss as set forth by GAAP, an estimate is made of the loss, and the appropriate accounting entries are reflected in the financial statements. At the present time, based on currently available information, the Registrants believe that any reasonably possible losses in excess of accrued amounts arising out of pending or threatened lawsuits or claims would not be quantitatively material to their financial statements and would not have a material adverse effect on their financial position, results of operations or cash flows.

Rate Matters and Regulation	12 Months Ended
Rate Matters and Regulation	Dec. 31, 2020
Regulated Operations [Abstract]
Rate Matters and Regulation	Rate Matters and Regulation Regulation and Rates OG&E's retail electric tariffs are regulated by the OCC in Oklahoma and by the APSC in Arkansas. The issuance of certain securities by OG&E is also regulated by the OCC and the APSC. OG&E's transmission activities, short-term borrowing authorization and accounting practices are subject to the jurisdiction of the FERC. The Secretary of the U.S. Department of Energy has jurisdiction over some of OG&E's facilities and operations. In 2020, 86 percent of OG&E's electric revenue was subject to the jurisdiction of the OCC, eight percent to the APSC and six percent to the FERC. The OCC and the APSC require that, among other things, (i) OGE Energy permits the OCC and the APSC access to the books and records of OGE Energy and its affiliates relating to transactions with OG&E; (ii) OGE Energy employ accounting and other procedures and controls to protect against subsidization of non-utility activities by OG&E's customers; and (iii) OGE Energy refrain from pledging OG&E assets or income for affiliate transactions. In addition, the FERC has access to the books and records of OGE Energy and its affiliates as the FERC deems relevant to costs incurred by OG&E or necessary or appropriate for the protection of utility customers with respect to the FERC jurisdictional rates. Completed Regulatory Matters APSC Proceedings Arkansas 2019 Formula Rate Plan Filing OG&E filed its second evaluation report under its Formula Rate Plan in October 2019. On February 28, 2020, the APSC approved a settlement agreement among OG&E, the General Staff of the APSC and the Office of the Arkansas Attorney General providing for a $5.2 million revenue increase, with rates effective April 1, 2020. The settling parties agreed that the Series I grid modernization projects are prudent in both action and cost and that the Series II grid modernization projects are prudent in action only and the determination of prudence of costs will be reserved until the actual historical costs are reviewed. The settling parties also agreed that OG&E will no longer use projections for the remaining initial term or extension of its current Formula Rate Plan and that all costs will be included for recovery for the first time in the historical year. Order Regarding COVID-19 On April 10, 2020, the APSC issued Order No. 1 related to COVID-19 and the provision of safe, adequate and reliable utility service at just and reasonable rates. Among other things, the APSC ordered the suspension of customer disconnects for non-payment during the pendency of the Arkansas Governor's emergency declaration or until the directive is rescinded by the APSC, neither of which have occurred yet, although the APSC has requested comments as to whether the moratorium should be lifted. The order encourages companies to provide reasonable payment arrangements once the suspension is lifted. The APSC also authorized utilities to establish regulatory assets to record costs resulting from the suspension of disconnections. These regulatory assets will be reviewed in future proceedings for reasonableness. The APSC ordered the General Staff of the APSC to consult with utilities to create a quarterly report to be used to report the costs incurred and saved that have been booked to the regulatory asset. OG&E is monitoring the regulatory activity regarding COVID-19 at the APSC and will consider the request for additional regulatory action by the APSC as needed. On May 1, 2020, OG&E filed a Request for Additional Actions and Tariff Deviation seeking relief from the Arkansas General Service Rules and OG&E's Terms and Conditions under the tariff, in order to allow for: more flexible deferred payment agreements for all customer classes, suspension of increased deposits due to non-payment and suspension of the removal of customers from certain billing and extended due date plans for late payments. In addition, OG&E requested that incremental expenses, such as additional personal protective equipment, increased sanitation efforts at facilities, implementing health-screening processes and securing temporary facilities for potential sequestration of critical operation personnel, be tracked in a regulatory asset. OG&E noted that all possible cost categories are not known currently and reserved the right to file subsequent requests as needed. On May 27, 2020, the APSC issued an order approving OG&E's request to deviate from the specified terms in the Arkansas General Service Rules and OG&E's Terms and Conditions to allow deferred payment arrangements to be offered to all customer classes and have more flexible payment arrangements. OG&E is authorized to record the expenses requested in its regulatory asset to defer and seek future recovery. The APSC found that because each utility has different cost recovery mechanisms and the magnitude of the utilities' expenses are unknown at this time, the APSC finds that it is premature to decide the exact recovery mechanism for any utility for COVID-19 related costs. Environmental Compliance Plan Rider In May 2019, OG&E filed an environmental compliance plan rider in Arkansas to recover its investment for the environmentally mandated costs associated with the Sooner Dry Scrubbers project and the conversion of Muskogee Units 4 and 5 to natural gas. The filing initiated an interim surcharge, subject to refund, that began with the first billing cycle of June 2019. OG&E had been reserving the amounts collected through the interim surcharge, pending APSC approval of OG&E's filing. A hearing on the merits was held in December 2019. Parties submitted additional briefs to the APSC in March 2020, which were requested due to certain intervenors questioning whether a company can utilize an environmental compliance plan rider while also being regulated under a formula rate plan. The APSC Staff concurred with OG&E that the rider may run concurrently with a formula rate plan, and the Arkansas Attorney General and other intervenors were in opposition. On July 31, 2020, OG&E's request to recover its investment for these environmentally mandated costs through the interim surcharge was not approved, as the APSC indicated OG&E could otherwise recover this investment, such as through the Formula Rate Plan Rider. As of December 31, 2020, OG&E has returned $5.3 million to customers that had been reserved for refund and has included those costs for recovery in its 2020 Formula Rate Plan filing. Arkansas Solar On July 29, 2020, OG&E submitted its application for a Certificate of Public Convenience and Necessity to construct and operate a five MW solar generation facility near Branch, Arkansas. On September 30, 2020, the parties reached a unanimous settlement agreement relating to the filing, and on November 6, 2020, the APSC issued a final order approving the settlement agreement. The terms of the settlement are as follows: (i) parties agree that OG&E has complied with Arkansas law and rules of practice and procedure and recommend granting a Certificate of Public Convenience and Necessity for the construction, ownership and operation of the project and associated tariffs; (ii) OG&E agrees that it would not seek cost recovery until its next general rate review or Formula Rate Plan filing; (iii) OG&E agrees to keep detailed records of final cost, for review at such time that cost recovery is sought, including all cost variance estimates, whereby a determination of prudency of cost may be made; and (iv) OG&E agrees to reserve 50 percent of the total expected energy produced for residential customers for the first 90 days of the program's initial subscription period. Net Metering Order On June 1, 2020, the APSC revised its net-metering rules. The revised rules retained 1:1 full credit for net excess generation of residential customers and commercial customers up to 1 MW without demand charges. For larger commercial customers, 1 MW to 20 MW, the APSC found that some cost shifting to non-net-metering customers may occur. While the rules retain 1:1 full credit for net excess generation, they allow for a grid charge. The grid charge is initially set at zero; however, a utility may request approval to revise the grid charge based on evidence that an unreasonable cost shift to non-net-metering customers is occurring. OG&E does not currently have a significant number of net-metering customers in Arkansas. OG&E amended its existing net-metering tariffs considering the new rules. The APSC approved OG&E's revised tariffs on February 5, 2021. OCC Proceedings OCC Public Utility Division Motion Regarding COVID-19 On April 28, 2020, the Director of the Public Utility Division filed an application requesting an order from the OCC authorizing action in response to COVID-19. The application requested that the OCC authorize the State's utilities to record as a regulatory asset increased bad debt expenses, costs associated with expanded payment plans, waived fees and incremental expenses that are directly related to the suspension of or delay in disconnection of service beginning March 15, 2020, which coincides with the issuance of the Oklahoma Governor's emergency declaration. The application also requested that the OCC allow utilities to defer additional expenses associated with ensuring the continuity of utility service, such as additional personal protective equipment, increased sanitation efforts at facilities, implementing heath-screening processes and securing temporary facilities for potential sequestration of critical operation personnel. The application asked the OCC to consider in future proceedings whether each utility's request for recovery of these regulatory assets is reasonable and necessary and to consider issues such as the incremental bad debt experienced over normal periods, the appropriate period of recovery for any approved amount of regulatory asset, any amount of carrying costs and other related matters. On May 7, 2020, the OCC ordered that each utility is authorized to record as a regulatory asset any increased bad debt expense, cost associated with expanded payment plans, waived fees and incremental expenses that are directly related to the suspension of or delay in disconnection of service beginning March 15, 2020 until September 2020, unless otherwise ordered by the OCC. The OCC will consider in future proceedings whether each utility's request for recovery of these regulatory assets is reasonable and necessary. The OCC will also consider issues such as the incremental bad debt experienced over normal periods, appropriate period of recovery for any approved amount of regulatory assets, any amounts of carrying costs thereon and other related matters. The OCC also authorized utilities to defer expenses associated with ensuring continuity of service and protecting utility personnel, customers and the general public. 2019 Oklahoma Fuel Prudency On June 16, 2020, the Public Utility Division Staff filed their application initiating the review of the 2019 fuel adjustment clause and prudence review. On December 30, 2020, the OCC issued a final order finding OG&E's 2019 fuel costs and related practices prudent. Oklahoma Grid Enhancement Plan On February 24, 2020, OG&E filed an application with the OCC for approval of a mechanism that allows for interim recovery of the costs associated with its grid enhancement plan. The plan includes approximately $800.0 million of strategic, data-driven investments, over five years, covering grid resiliency, grid automation, communication systems and technology platforms and applications. On May 19, 2020, the OCC temporarily suspended the procedural schedule in light of various conditions related to the COVID-19 pandemic and the uncertainty surrounding the method and date in which the hearing on the merits may occur. On July 9, 2020, a prehearing conference was held before the Administrative Law Judge to establish a procedural schedule and lift the stay ordered on May 19, 2020. On July 23, 2020, the OCC issued an order approving the amended procedural schedule and thereby lifting the stay. On October 5, 2020, OG&E filed a Joint Stipulation and Settlement Agreement that included the following key terms: (i) cost recovery through a rider mechanism will be limited to projects placed in service in 2020 and 2021, capped at a revenue requirement of $7.0 million annually and only include communication, automation and technology systems projects; (ii) no operation and maintenance expense will be included in the rider mechanism; (iii) the rider mechanism will terminate by the issuance of a final order in OG&E's next general rate review or October 31, 2022, whichever occurs first; (iv) the rider mechanism rate of return will be capped at OG&E's current cost of capital; and (v) all cost recovery is subject to true-up and refund in OG&E's next general rate review. On November 5, 2020, the OCC issued a final order approving the Joint Stipulation and Settlement Agreement. In compliance with the final order, OG&E submitted a final list of projects for inclusion in the rider mechanism on December 5, 2020 and a revised rider mechanism for initial recovery of costs on December 15, 2020. The rider mechanism became effective on February 1, 2021. Any capital investment falling outside the criteria of the rider mechanism will be included in OG&E's next general rate review for recovery. Pending Regulatory Matters Various proceedings pending before state or federal regulatory agencies are described below. Unless stated otherwise, the Registrants cannot predict when the regulatory agency will act or what action the regulatory agency will take. The Registrants' financial results are dependent in part on timely and adequate decisions by the regulatory agencies that set OG&E's rates. FERC Proceedings Order for Sponsored Transmission Upgrades within SPP Under the SPP Open Access Transmission Tariff, costs of participant-funded, or "sponsored," transmission upgrades may be recovered from other SPP customers whose transmission service depends on capacity enabled by the upgrade. The SPP Open Access Transmission Tariff required the SPP to charge for these upgrades beginning in 2008, but the SPP had not been charging its customers for these upgrades due to information system limitations. However, the SPP had informed participants in the market that these charges would be forthcoming. In July 2016, the FERC granted the SPP's request to recover the charges not billed since 2008. The SPP subsequently billed OG&E for these charges and credited OG&E related to transmission upgrades that OG&E had sponsored, which resulted in OG&E being a net receiver of sponsored upgrade credits. The majority of these net credits were refunded to customers through OG&E's various rate riders that include SPP activity with the remaining amounts retained by OG&E. Several companies that were net payers of Z2 charges sought rehearing of the FERC's July 2016 order; however, in November 2017, the FERC denied the rehearing requests. In January 2018, one of the impacted companies appealed the FERC's decision to the U.S. Court of Appeals for the District of Columbia Circuit. In July 2018, that court granted a motion requested by the FERC that the case be remanded back to the FERC for further examination and proceedings. In February 2019, the FERC reversed its July 2016 order and November 2017 rehearing denial, ruled that the SPP violated its tariff to charge for the 2008 - 2015 period in 2016, held that the SPP tariff provision that prohibited those charges could not be waived and ordered the SPP to develop a plan to refund the payments but not to implement the refunds until further ordered to do so. In response, in April 2019, OG&E filed a request for rehearing with the FERC, and in May 2019, OG&E filed a FERC 206 complaint against the SPP, alleging that the SPP's forced unwinding of the revenue credit payments to OG&E would violate the provisions of the Sponsored Upgrade Agreement and of the applicable tariff. OG&E's filing requested that the FERC rule that the SPP is not entitled to seek refunds or in any other way seek to unwind the revenue credit payments it had paid to OG&E pursuant to the Sponsored Upgrade Agreement. The SPP's response to OG&E's filing agreed that OG&E should be entitled to keep its Z2 payments and argued that the SPP should not be held responsible for those payments if refunds are ordered. Further, the SPP has requested the FERC to negotiate a global settlement with all impacted parties, including other project sponsors who, like OG&E, have also filed complaints at FERC contending that the payments they have received cannot properly be unwound. On February 20, 2020, the FERC denied OG&E's request for rehearing of its February 2019 order, denying the waiver and ruling that the SPP must seek refunds from project sponsors for Z2 payments for the 2008 through 2015 period and pay them back to transmission owners. The FERC also denied the SPP's request for a stay and for institution of settlement procedures. The FERC stated it would not institute settlement procedures unless parties on both sides of the matter requested them. The FERC did not rule on OG&E's complaint or the complaints of other project sponsors, or consider the SPP's refund plan. The FERC thus has not set any date for payment of refunds. On March 2, 2020, OG&E petitioned the U.S. Court of Appeals for the District of Columbia Circuit for review of the FERC's order denying the waiver and requiring refunds. The appeal will likely be decided by the second quarter of 2021. The Registrants cannot predict the outcome of this proceeding based on currently available information, and as of December 31, 2020 and at present time, the Registrants have not reserved an amount for a potential refund. If the reversal of the July 2016 FERC order remains intact, OG&E estimates it would be required to refund $13.0 million, which is net of amounts paid to other utilities for upgrades and would be subject to interest at the FERC-approved rate. If refunds were required, recovery of these upgrade credits would shift to future periods. Of the $13.0 million, the Registrants would be impacted by $5.0 million in expense that initially benefited the Registrants in 2016, and OG&E customers would incur a net impact of $8.0 million in expense through rider mechanisms or the FERC formula rate. On January 31, 2020, the FERC acted on an SPP proposal to eliminate Attachment Z2 revenue crediting and replace it with a different rate mechanism that would provide project sponsors, such as OG&E, the same level of recovery, and rejected the proposal to the extent it would limit recovery to the amount of the upgrade sponsor's directly assigned upgrade costs with interest. The SPP resubmitted a proposal on April 29, 2020 without this limited recovery, and with the alternative rate mechanism, and the FERC approved it on June 30, 2020, effective July 1, 2020. No party sought rehearing of the order, and it is now final. This order would only prospectively impact OG&E and its recovery of any future upgrade costs that it may incur as a project sponsor. All of the existing projects that are eligible to receive revenue credits under Attachment Z2, which includes the $13.0 million at issue in OG&E's appeal as discussed above, will continue to do so. APSC Proceedings Arkansas 2020 Formula Rate Plan Filing On October 1, 2020, OG&E filed its third evaluation report under its Formula Rate Plan, and on January 28, 2021, OG&E entered into a non-unanimous settlement agreement with the APSC General Staff and the Office of the Arkansas Attorney General. The only non-signatory to the settlement agreement has agreed not to oppose the settlement. The settlement agreement includes a revenue increase of $6.7 million, which is the maximum amount statutorily allowed in this filing. Additionally, the settling parties will not object to OG&E's request for a finding that the Arkansas Series II grid modernization projects included in this filing are prudent in cost. A final order is requested from the APSC in March 2021, and new rates will become effective April 1, 2021. Disconnection Procedures Related to COVID-19 On September 17, 2020, the APSC issued Order No. 9 inviting comments from all jurisdictional utilities and any other interested stakeholders on specific questions related to whether a moratorium on service terminations should be lifted and if so, how the resumption of disconnections should occur. The APSC also ordered utilities to submit a detailed "Transitional Plan" outlining how utilities propose to reinstate routine service disconnection activities and collection of past due amounts once the moratorium is lifted. OG&E submitted its proposed Transitional Plan on October 14, 2020. The APSC General Staff thereafter filed reports for utilities that set forth recommendations as to the form of notice that should occur prior to lifting the moratorium and resuming disconnections, as well as payment arrangements that should be made available to customers. On February 8, 2021, the APSC issued Order No. 15 announcing a target date of May 3, 2021 to lift the moratorium on disconnections and requiring certain conditions and requirements that utilities must meet before disconnections may resume. Such requirements include, among other things, immediate communication to customers, notice periods for disconnections and deferred payment arrangements. In the interim, the APSC is expected to continue to review all information relevant to a discontinuation of the moratorium and is expected to issue an order on March 26, 2021, either confirming the lifting of the moratorium on disconnections, or extending the moratorium. OCC Proceedings Oklahoma Retail Electric Supplier Certified Territory Act Causes Several rural electric cooperative electricity suppliers have filed complaints with the OCC alleging that OG&E has violated the Oklahoma Retail Electric Supplier Certified Territory Act. OG&E believes it is lawfully serving customers specifically exempted from this act and has presented evidence and testimony to the OCC supporting its position. There have been five complaint cases initiated at the OCC, and the OCC has issued decisions on each of them. The OCC ruled in favor of the electric cooperatives in three of those cases and ruled in favor of OG&E in two of those cases. All five of those cases have been appealed to the Oklahoma Supreme Court, where they have been made companion cases but will be individually briefed and have individual final decisions. If the Oklahoma Supreme Court ultimately were to find that some or all of the customers being served are not exempted from the Oklahoma Retail Electric Supplier Certified Territory Act, OG&E would have to evaluate the recoverability of some plant investments made to serve these customers. The total amount of OG&E's plant investments made to serve the customers in all five cases is approximately $28.0 million, of which $11.7 million applies to the three cases where the OCC ruled in favor of the electric cooperatives. In addition to the evaluation of the recoverability of the investments, OG&E may also be required to reimburse certified territory suppliers for an amount of lost revenue. The amount of such lost revenue would depend on how the OCC calculates the revenue requirement but could range from approximately $14.5 million to $21.7 million for all five cases, of which $1.4 million to $2.3 million would apply to the three cases where the OCC ruled in favor of the electric cooperatives. October 2020 Storm Examination In October 2020, a major ice storm moved through OG&E's service territory which caused significant damage to the system. On November 17, 2020, the Public Utility Division of the OCC initiated an examination and review of all distribution utilities and cooperatives affected by the storm into the mitigation efforts, restoration processes and proposed improvements for future related or similar events. Respondents are required to provide certain information related to the examination, and the OCC may request additional relief as the examination proceeds. No procedural schedule has been proposed currently; however, OG&E is responding to discovery requests. February 2021 Extreme Cold Weather Event In February 2021, OG&E's service territory experienced an unprecedented, prolonged, cold spell that resulted in record winter peak demand for electricity and extreme natural gas and purchased power prices. OG&E's natural gas costs for the month of February 2021 exceeded the total cost for all of 2020. Fuel and purchased power costs are recovered through OG&E's Oklahoma and Arkansas fuel adjustment clauses. Estimates of the total regulatory asset for fuel and purchased power costs that will be recorded are still under development but are expected to be in the range of $800.0 million to $1.0 billion. For approximately 58,000 guaranteed flat bill customers, representing approximately three percent of load, OG&E may be unable to seek recovery for the incremental fuel and purchased power costs that are included in customers' guaranteed flat bill agreements which would result in a loss to OG&E. Full impacts cannot be determined until all settlements and invoices are received for this period. While borrowing availability still exists within the Registrants' credit facilities, OGE Energy has secured a commitment for $1.0 billion in additional short-term financing to provide additional liquidity to help cover these increased fuel and purchased power costs. On February 24, 2021, OG&E submitted an application to the OCC outlining a two-step approach for regulatory treatment for the fuel and purchased power costs associated with the unprecedented weather event. The steps include: (i) an intra-year fuel clause increase to be effective April 1, 2021; and (ii) a request for regulatory asset treatment at OG&E's weighted average cost of capital for the remaining fuel and purchased power costs. OG&E anticipates making a similar filing with the APSC.

Schedule II

9 Months Ended

Sep. 30, 2020

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]

SCHEDULE II - Valuation and Qualifying Accounts


			Additions
Description	Balance at Beginning of Period		Charged to Costs and Expenses		Deductions (A)		Balance at End of Period
(In millions)
Balance at December 31, 2018
Reserve for Uncollectible Accounts	$	1.5	$	3.4	$	3.2	$	1.7
Balance at December 31, 2019
Reserve for Uncollectible Accounts	$	1.7	$	2.2	$	2.4	$	1.5
Balance at December 31, 2020
Reserve for Uncollectible Accounts	$	1.5	$	3.0	$	1.9	$	2.6

(A)Uncollectible accounts receivable written off, net of recoveries.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Consolidation, Policy [Policy Text Block]

Organization

method of accounting. In February 2021, Enable entered into a definitive merger agreement with Energy Transfer. For further discussion, see Note 5.

Public Utilities, Policy [Policy Text Block]

Accounting Records

Management continuously monitors the future recoverability of regulatory assets. When in management's judgment future recovery becomes impaired, the amount of the regulatory asset is adjusted, as appropriate. If OG&E were required to discontinue the application of accounting principles for certain types of rate-regulated activities for some or all of its operations, it could result in writing off the related regulatory assets or liabilities, which could have significant financial effects.

Use of Estimates, Policy [Policy Text Block]

Use of Estimates

Cash and Cash Equivalents, Policy [Policy Text Block]

Cash and Cash Equivalents

Allowance for Uncollectible Accounts Receivable, Policy

Inventory, Policy [Policy Text Block]

Fuel Inventories

Property, Plant and Equipment, Policy [Policy Text Block]

Property, Plant and Equipment

Depreciation and Amortization, Policy [Policy Text Block]

Depreciation and Amortization

Equity Method Investments [Policy Text Block]

Investment in Unconsolidated Affiliates

Asset Retirement Obligation [Policy Text Block]

Asset Retirement ObligationsOG&E has asset retirement obligations primarily associated with the removal of company-owned wind turbines on leased land, as well as the removal of asbestos from certain power generating stations. OG&E has recorded asset retirement obligations that are being accreted over their respective lives ranging from five to 68 years. Asset retirement obligations are included in Other Deferred Credits in the Registrants' balance sheets.

Allowance for Funds Used During Construction, Policy [Policy Text Block]

Allowance for Funds Used During Construction

Collection of Sales Tax, Policy [Policy Text Block]

Collection of Sales Tax

Revenue Recognition, Policy [Policy Text Block]

Revenue Recognition

General

Integrated Market and Transmission

Other Revenues

Fuel Adjustment Clauses, Policy [Policy Text Block]

Fuel Adjustment Clauses

Lessee, Leases

Income Taxes, Policy [Policy Text Block]

Income Taxes

Accrued Vacation, Policy [Policy Text Block]

Accrued Vacation

Environmental Costs, Policy [Policy Text Block]

Accruals for environmental costs are recognized when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated. Costs are charged to expense or deferred as a regulatory asset based on expected recovery from customers in future rates, if they relate to the remediation of conditions caused by past operations or if they are not expected to mitigate or prevent contamination from future operations. Where environmental expenditures relate to facilities currently in use, such as pollution control equipment, the costs may be capitalized and depreciated over the future service periods. Estimated remediation costs are recorded at undiscounted amounts, independent of any insurance or rate recovery, based on prior experience, assessments and current technology. Accrued obligations are regularly adjusted as environmental assessments and estimates are revised and remediation efforts proceed. For sites where OG&E has been designated as one of several potentially responsible parties, the amount accrued represents OG&E's estimated share of the cost. OG&E had $25.0 million and $18.7 million in accrued environmental liabilities at December 31, 2020 and 2019, respectively, which are included in OG&E's asset retirement obligations.

Fair Value of Financial Instruments, Policy [Policy Text Block]

Fair Value Measurements

Level 1 inputs are quoted prices in active markets for identical unrestricted assets or liabilities that are accessible at the measurement date.

The Registrants had no financial instruments measured at fair value on a recurring basis at December 31, 2020 and 2019.

Share-based Compensation, Option and Incentive Plans, Policy [Policy Text Block]

Performance Units

Performance Units – Total Shareholder Return

The fair value of the performance units based on total shareholder return was estimated on the grant date using a lattice-based valuation model that factors in information, including the expected dividend yield, expected price volatility, risk-free interest rate and the probable outcome of the market condition, over the expected life of the performance units. Compensation expense for the performance units is a fixed amount determined at the grant date fair value and is recognized over the primarily three-year award cycle regardless of whether performance units are awarded at the end of the award cycle. Dividends are accrued on a quarterly basis pending achievement of payout criteria and are included in the fair value calculations. Expected price volatility is based on the historical volatility of OGE Energy's common stock for the past three years and is simulated using the Geometric Brownian Motion process. The risk-free interest rate for the performance unit grants is based on the three-year U.S. Treasury yield curve in effect at the time of the grant. The expected life of the units is based on the non-vested period since inception of the award cycle. There are no post-vesting restrictions related to OGE Energy's performance units based on total shareholder return.Performance Units – Earnings Per ShareThe fair value of the performance units based on earnings per share is based on grant date fair value which is equivalent to the price of one share of OGE Energy's common stock on the date of grant. The fair value of performance units based on earnings per share varies as the number of performance units that will vest is based on the grant date fair value of the units and the probable outcome of the performance condition. OGE Energy reassesses at each reporting date whether achievement of the performance condition is probable and accrues compensation expense if and when achievement of the performance condition is probable. As a result, the compensation expense recognized for these performance units can vary from period to period. There are no post-vesting restrictions related to OGE Energy's performance units based on earnings per share.

Restricted Stock Units

Earnings Per Share, Policy [Policy Text Block]

Earnings (Loss) Per Share

Pension and Other Postretirement Plans, Policy [Policy Text Block]

Pension Plan and Restoration of Retirement Income Plan

OG&E's employees participate in OGE Energy's Pension Plan and Restoration of Retirement Income Plan.

Postretirement Benefit Plans

Postemployment Benefit Plans, Policy [Policy Text Block]

Post-Employment Benefit Plan

Plan Investments, Policies and Strategies, Policy [Policy Text Block]

Pension Plan Investments, Policies and Strategies


Projected Benefit Obligation Funded Status Thresholds	<90%	95%	100%	105%	110%	115%	120%
Fixed income	50%	58%	65%	73%	80%	85%	90%
Equity	50%	42%	35%	27%	20%	15%	10%
Total	100%	100%	100%	100%	100%	100%	100%

Within the portfolio's overall allocation to equities, the funds are allocated according to the guidelines in the following table.


Asset Class	Target Allocation	Minimum	Maximum
Domestic Large Cap Equity	40%	35%	60%
Domestic Mid-Cap Equity	15%	5%	25%
Domestic Small-Cap Equity	25%	5%	30%
International Equity	20%	10%	30%

The following table presents a list of each asset class utilized with appropriate comparative benchmark(s) each manager is evaluated against and the focus of the asset class.


Asset Class	Comparative Benchmark(s)	Focus of Asset Class
Active Duration Fixed Income (A)(B)	Bloomberg Barclays Aggregate	l Maximize risk-adjusted performance while providing long bond exposure managed according to the manager's forecast on interest rates. l All invested assets must reach at or above Baa3 or BBB- investment grade. l Limited five percent exposure to any single issuer, except the U.S. Government or affiliates.

Long Duration Fixed Income (A)(B)	Duration blended Barclays Long Government/Credit & Barclays Universal	l Maximize risk-adjusted performance. l At least 75 percent of invested assets much reach at or above Baaa3 or BBB- investment grade. l Limited five percent exposure to any single issuer, except the U.S. Government or affiliates. l May invest up to 10 percent of the market value in convertible bonds as long as quality guidelines are met. l May invest up to 15 percent of the market value in private placement, including 144A securities with or without registration rights and allow for futures to be traded in the portfolio.
Equity Index (B)(C)	Standard & Poor's 500 Index	l Focus on replicating the performance of the S&P 500 Index.


Mid-Cap Equity (B)(C)	Russell Midcap Index Russell Midcap Value Index	l Focus on undervalued stocks expected to earn average return and pay out higher than average dividends. l Invest in companies with market capitalizations lower than average company on public exchanges: l Price/earnings ratio at or near referenced index; l Small dividend yield and return on equity at or near referenced index; and l Earnings per share growth rate at or near referenced index.

Small-Cap Equity (B)(C)	Russell 2000 Index Russell 2000 Value Index


International Equity (D)			Morgan Stanley Capital International ACWI ex-U.S.			l Invest in non-dollar denominated equity securities. l Diversify the overall trust investments.

(A)Investment grades are by Moody's Investors Service, S&P Global Ratings or Fitch Ratings.

(B)The purchase of any of OGE Energy's equity, debt or other securities is prohibited.

Pension and Other Postretirement Plans, Nonpension Benefits, Policy [Policy Text Block]

401(k) Plan

Deferred Compensation Plan

Fair Value Measures and Disclosures (Policies)	12 Months Ended
Fair Value Measures and Disclosures (Policies)	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurement, Policy	Nonrecurring Fair Value Measurements As further discussed in Note 5, OGE Energy recorded an impairment on its investment in Enable in March 2020. The nonrecurring fair value measurement consisted of calculating a 20-trading day volume weighted average price for Enable's common units through March 31, 2020. This method of valuation was determined to be representative of the fair value of Enable's common units as it incorporated market prices during the period and reduced the impact of volatility that a single day could represent. OGE Energy concluded that this valuation method resulted in a Level 3 nonrecurring fair value measurement.

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Regulatory Assets and Liabilities [Table Text Block]

The following table presents a summary of OG&E's regulatory assets and liabilities.


December 31 (In millions)	2020		2019
REGULATORY ASSETS
Current:
SPP cost tracker under recovery (A)	$	7.0	$	—
Generation Capacity Replacement rider under recovery (A)	4.4		3.7
Fuel clause under recoveries	—		39.5

Other (A)	8.4		5.5
Total current regulatory assets	$	19.8	$	48.7
Non-current:
Benefit obligations regulatory asset	$	164.9	$	167.2
Deferred storm expenses	158.8		65.5
Sooner Dry Scrubbers	19.7		20.6
Pension tracker	18.1		2.3
Smart Grid	11.2		18.4
Unamortized loss on reacquired debt	9.7		10.6
Arkansas deferred pension expenses	9.3		8.0

Frontier Plant deferred expenses	6.4		—
COVID-19 impacts	6.4		—
Other	11.1		13.4
Total non-current regulatory assets	$	415.6	$	306.0
REGULATORY LIABILITIES
Current:
Fuel clause over recoveries	$	28.6	$	4.8
Oklahoma demand program rider over recovery (B)	1.5		2.0
Reserve for tax refund and interim surcharge (B)	0.8		12.7
SPP cost tracker over recovery (B)	—		2.6

Other (B)	4.2		6.9
Total current regulatory liabilities	$	35.1	$	29.0
Non-current:
Income taxes refundable to customers, net	$	867.4	$	899.2
Accrued removal obligations, net	316.8		318.5

Other	4.7		5.8
Total non-current regulatory liabilities	$	1,188.9	$	1,223.5

(A)Included in Other Current Assets in the balance sheets.

(B)Included in Other Current Liabilities in the balance sheets.

Components of Benefit Obligation Regulatory Asset [Table Text Block]

The following table presents a summary of the components of the benefit obligations regulatory asset.


December 31 (In millions)	2020		2019
Pension Plan and Restoration of Retirement Income Plan:
Net loss	$	147.3	$	160.5

Postretirement Benefit Plans:
Net loss	26.2		23.3
Prior service cost	(8.6)		(16.6)
Total	$	164.9	$	167.2

Schedule of Jointly Owned Utility Plants [Table Text Block]


December 31, 2020 (In millions)	Percentage Ownership		Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
McClain Plant (A)	77	%	$	257.1	$	96.0	$	161.1
Redbud Plant (A)(B)	51	%	$	531.8	$	181.9	$	349.9

(A)Construction work in progress was $0.1 million and $1.8 million for the McClain and Redbud Plants, respectively.

(B)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $67.3 million.


December 31, 2019 (In millions)	Percentage Ownership		Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
McClain Plant (A)	77	%	$	254.4	$	83.5	$	170.9
Redbud Plant (A)(B)	51	%	$	529.9	$	159.0	$	370.9

(A)Construction work in progress was $0.2 million and $1.4 million for the McClain and Redbud Plants, respectively.

(B)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $61.8 million.

Property, Plant and Equipment [Table Text Block]

The following tables present the Registrants' major classes of property, plant and equipment and related accumulated depreciation.


December 31, 2020 (In millions)	Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
OG&E:
Distribution assets	$	4,809.9	$	1,422.1	$	3,387.8
Electric generation assets (A)	4,932.2		1,713.6		3,218.6
Transmission assets (B)	2,944.6		591.7		2,352.9
Intangible plant	254.1		153.9		100.2
Other property and equipment	495.3		186.3		309.0
OG&E property, plant and equipment	13,436.1		4,067.6		9,368.5
Non-OG&E property, plant and equipment	6.1		—		6.1
Total OGE Energy property, plant and equipment	$	13,442.2	$	4,067.6	$	9,374.6

(A)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $67.3 million.

(B)This amount includes a plant acquisition adjustment of $3.3 million and accumulated amortization of $0.9 million.


December 31, 2019 (In millions)	Total Property, Plant and Equipment		Accumulated Depreciation		Net Property, Plant and Equipment
OG&E:
Distribution assets	$	4,468.6	$	1,381.1	$	3,087.5
Electric generation assets (A)	4,838.6		1,601.0		3,237.6
Transmission assets (B)	2,901.1		565.5		2,335.6
Intangible plant	225.2		145.4		79.8
Other property and equipment	473.1		175.1		298.0
OG&E property, plant and equipment	12,906.6		3,868.1		9,038.5
Non-OG&E property, plant and equipment	6.1		—		6.1
Total OGE Energy property, plant and equipment	$	12,912.7	$	3,868.1	$	9,044.6

(A)This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $61.8 million.

(B)This amount includes a plant acquisition adjustment of $3.3 million and accumulated amortization of $0.8 million.

Schedule of Change in Asset Retirement Obligation [Table Text Block]

The following table presents changes to OG&E's asset retirement obligations during the years ended December 31, 2020 and 2019.


(In millions)	2020		2019
Balance at January 1	$	73.5	$	83.9
Accretion expense	0.5		1.0
Revisions in estimated cash flows (A)	5.8		(2.4)

Liabilities settled (B)	(0.2)		(9.0)
Balance at December 31	$	79.6	$	73.5

(A)Assumptions changed related to the estimated timing and estimated cost of the removal of asbestos at OG&E's generating facilities.

(B)Asset retirement obligations were settled for asbestos removal at one of OG&E's generating facilities

Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]

The following table presents changes in the components of accumulated other comprehensive income (loss) attributable to OGE Energy during 2019 and 2020. All amounts below are presented net of tax.


	Pension Plan and Restoration of Retirement Income Plan		Postretirement Benefit Plans
(In millions)	Net Gain (Loss)		Net Gain (Loss)		Prior Service Cost (Credit)		Other Comprehensive Loss from Unconsolidated Affiliates		Total





Balance at December 31, 2018	$	(38.8)	$	4.6	$	5.3	$	—	$	(28.9)
Other comprehensive loss before reclassifications	(8.3)		(0.2)		—		(0.6)		(9.1)
Amounts reclassified from accumulated other comprehensive income (loss)	3.4		(0.2)		(1.7)		—		1.5

Settlement cost	8.6		—		—		—		8.6
Net current period other comprehensive income (loss)	3.7		(0.4)		(1.7)		(0.6)		1.0
Balance at December 31, 2019	(35.1)		4.2		3.6		(0.6)		(27.9)
Other comprehensive income (loss) before reclassifications	(5.1)		(2.4)		—		(0.7)		(8.2)
Amounts reclassified from accumulated other comprehensive income (loss)	3.9		(0.1)		(1.7)		—		2.1
Curtailment cost	—		(0.3)		—		—		(0.3)
Settlement cost	2.2		—		—		—		2.2
Net current period other comprehensive income (loss)	1.0		(2.8)		(1.7)		(0.7)		(4.2)
Balance at December 31, 2020	$	(34.1)	$	1.4	$	1.9	$	(1.3)	$	(32.1)

Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]


Details about Accumulated Other Comprehensive Income (Loss) Components	Amount Reclassified from Accumulated Other Comprehensive Income (Loss)				Affected Line Item in OGE Energy's Statements of Income
	Year Ended December 31,
(In millions)	2020		2019









Amortization of Pension Plan and Restoration of Retirement Income Plan items:
Actuarial losses	$	(5.1)	$	(4.5)	(A)

Settlement cost	(2.9)		(11.3)		(A)
	(8.0)		(15.8)		Income (Loss) Before Taxes
	(1.9)		(3.8)		Income Tax Expense (Benefit)


	$	(6.1)	$	(12.0)	Net Income (Loss)

Amortization of postretirement benefit plans items:

Prior service credit	$	2.3	$	2.3	(A)
Curtailment cost	0.4		—		(A)
Actuarial gains	0.1		0.2		(A)
	2.8		2.5		Income (Loss) Before Taxes
	0.7		0.6		Income Tax Expense (Benefit)
	$	2.1	$	1.9	Net Income (Loss)



Total reclassifications for the period, net of tax	$	(4.0)	$	(10.1)	Net Income (Loss)

(A)These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost (see Note 13 for additional information).

Revenue from Contracts with Customers (Tables)

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue [Table Text Block]




	Year Ended December 31,
(In millions)	2020		2019		2018
Residential	$	842.7	$	865.8	$	877.8
Commercial	465.6		486.6		500.0
Industrial	192.6		217.8		228.9
Oilfield	169.2		200.4		190.4
Public authorities and street light	172.3		190.3		197.4
System sales revenues	1,842.4		1,960.9		1,994.5
Provision for rate refund	3.8		(0.9)		(6.0)
Integrated market	49.6		38.4		48.7
Transmission	143.3		148.0		147.4
Other	30.7		29.1		27.1
Revenues from contracts with customers	$	2,069.8	$	2,175.5	$	2,211.7

Leases, Codification Topic 842 (Tables)

12 Months Ended

Dec. 31, 2020

Equity Method Investments and Joint Ventures [Abstract]

Lease, Cost

The following table presents amounts recognized for operating leases in the Registrants' cash flow statements and balance sheets and supplemental information related to those amounts recognized.


	OGE Energy						OG&E
	Year Ended December 31,						Year Ended December 31,
(In millions)	2020			2019			2020			2019












Cash paid for amounts included in the measurement of lease liabilities:

Operating cash flows for operating leases	$	6.4		$	5.6		$	5.5		$	4.8

Right-of-use assets obtained in exchange for new operating lease liabilities	$	1.4		$	10.7		$	1.4		$	10.7




(Dollars in millions)	December 31, 2020			December 31, 2019			December 31, 2020			December 31, 2019
Right-of-use assets at period end (A)	$	37.6		$	40.9		$	37.0		$	39.6
Operating lease liabilities at period end (B)	$	42.3		$	45.8		$	41.7		$	44.3
Operating lease weighted-average remaining lease term (in years)	12.5			13.1			12.7			13.5
Operating lease weighted-average discount rate	3.9		%	3.9		%	3.9		%	3.9		%

(A)Included in Property, Plant and Equipment in the Registrants' balance sheets.

(B)Included in Other Deferred Credits and Other Liabilities in the Registrants' balance sheets.

The following table presents a maturity analysis of the Registrants' operating lease liabilities.



Future minimum operating lease payments as of December 31:	OGE Energy		OG&E
(In millions)

2021	$	6.3	$	5.7
2022	5.7		5.7
2023	5.1		5.1
2024	3.2		3.2
2025	3.0		3.0
Thereafter	31.7		31.7
Total future minimum lease payments	55.0		54.4
Less: Imputed interest	12.7		12.7
Present value of net minimum lease payments	$	42.3	$	41.7

Investment in Unconsolidated Affiliate (Tables)

12 Months Ended

Dec. 31, 2020

Summarized Balance Sheet Financial Information, Equity Method Investment [Table Text Block]

The following tables present summarized unaudited financial information for 100 percent of Enable as of December 31, 2020 and 2019 and for the years ended December 31, 2020, 2019 and 2018.


	December 31,
Balance Sheet	2020		2019
(In millions)
Current assets	$	381	$	389
Non-current assets	$	11,348	$	11,877
Current liabilities	$	582	$	780
Non-current liabilities	$	4,052	$	4,077

Summarized Income Statement Financial Information, Equity Method Investment [Table Text Block]


	Year Ended December 31,
Income Statement	2020		2019		2018
(In millions)
Total revenues	$	2,463	$	2,960	$	3,431
Cost of natural gas and NGLs	$	965	$	1,279	$	1,819
Operating income	$	465	$	569	$	648
Net income	$	52	$	360	$	485

Reconciliation of Equity in Earnings of Unconsolidated Affiliates [Table Text Block]


	Year Ended December 31,
(In millions)	2020			2019			2018
Enable net income	$	52.0		$	360.0		$	485.3



OGE Energy's percent ownership at period end	25.5		%	25.5		%	25.6		%
OGE Energy's portion of Enable net income	$	13.2		$	91.8		$	124.4
Amortization of basis difference and dilution recognition (A)	98.8			22.1			28.4
Impairment of OGE Energy's equity method investment in Enable	(780.0)			—			—
Equity in earnings (losses) of unconsolidated affiliates (B)	$	(668.0)		$	113.9		$	152.8

(A) Includes loss on dilution, net of proportional basis difference recognition.

Reconciliation of Basis Difference [Table Text Block]


(In millions)
Basis difference at December 31, 2019	$	652.5

Amortization of basis difference (A)	(100.2)
Impairment of OGE Energy's equity method investment in Enable	780.0
Basis difference at December 31, 2020	$	1,332.3

(A) Includes proportional basis difference recognition due to dilution.

The following table presents summarized related party transactions between OG&E and Enable during the years ended December 31, 2020, 2019 and 2018.


	Year Ended December 31,
(In millions)	2020		2019		2018
Operating revenues:
Electricity to power electric compression assets	$	15.1	$	15.9	$	16.3
Cost of sales:
Natural gas transportation services	$	32.8	$	41.2	$	37.9

Natural gas purchases (sales)	$	2.7	$	(6.0)	$	(3.2)

Related Party Disclosures (Tables)

12 Months Ended

Dec. 31, 2020

The following table presents summarized related party transactions between OG&E and Enable during the years ended December 31, 2020, 2019 and 2018.


	Year Ended December 31,
(In millions)	2020		2019		2018
Operating revenues:
Electricity to power electric compression assets	$	15.1	$	15.9	$	16.3
Cost of sales:
Natural gas transportation services	$	32.8	$	41.2	$	37.9

Natural gas purchases (sales)	$	2.7	$	(6.0)	$	(3.2)

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value, by Balance Sheet Grouping [Table Text Block]

The following table presents the carrying amount and fair value of the Registrants' financial instruments at December 31, 2020 and 2019, as well as the classification level within the fair value hierarchy.


	2020				2019
December 31 (In millions)	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Classification
Long-term Debt (including Long-term Debt due within one year):
OG&E Senior Notes	$	3,349.6	$	4,182.1	$	3,050.3	$	3,500.4	Level 2
OG&E Industrial Authority Bonds	$	135.4	$	135.4	$	135.4	$	135.4	Level 2
Tinker Debt	$	9.4	$	10.7	$	9.5	$	10.0	Level 3

Stock Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Stock-Based Compensation [Abstract]

Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block]


	OGE Energy						OG&E
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018
Performance units:
Total shareholder return	$	7.9	$	8.7	$	8.2	$	2.3	$	3.0	$	2.8
Earnings per share	1.0		4.3		5.1		0.3		1.5		1.8
Total performance units	8.9		13.0		13.3		2.6		4.5		4.6
Restricted stock units	0.9		0.9		0.1		0.4		0.4		—


Total compensation expense	$	9.8	$	13.9	$	13.4	$	3.0	$	4.9	$	4.6
Income tax benefit	$	2.5	$	3.6	$	3.4	$	0.8	$	1.3	$	1.2

Performance Units Total Shareholder Return Valuation Assumptions [Table Text Block]

The following table presents the number of performance units granted based on total shareholder return and the assumptions used to calculate the grant date fair value of the performance units based on total shareholder return.


	OGE Energy									OG&E
	2020			2019			2018			2020			2019			2018
Number of units granted	201,552			208,647			261,916			67,975			68,396			91,940
Fair value of units granted	$	38.03		$	47.00		$	36.86		$	38.03		$	47.00		$	36.86
Expected dividend yield	3.5		%	4.0		%	3.6		%	3.5		%	4.0		%	3.6		%
Expected price volatility	15.0		%	17.0		%	19.0		%	15.0		%	17.0		%	19.0		%
Risk-free interest rate	1.17		%	2.47		%	2.38		%	1.17		%	2.47		%	2.38		%
Expected life of units (in years)	2.85			2.86			2.86			2.85			2.86			2.86

Restricted Stock Valuation Assumptions [Table Text Block]

The following table presents the number of restricted stock units granted and the grant date fair value.


	OGE Energy						OG&E
	2020		2019		2018		2020		2019		2018
Restricted stock units granted	67,193		75,929		826		22,665		26,141		—
Fair value of restricted stock units granted	$	43.69	$	41.71	$	36.28	$	43.69	$	41.63	$	—

Share-based Compensation, Activity [Table Text Block]

The following tables present a summary of the activity for the Registrants' performance units and restricted stock units for the year ended December 31, 2020.


OGE Energy	Performance Units								Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
(Dollars in millions)	Number of Units		Aggregate Intrinsic Value		Number of Units		Aggregate Intrinsic Value		Number of Shares	Aggregate Intrinsic Value
Units/shares outstanding at 12/31/19	664,817				155,171				72,880
Granted	201,552	(A)			—				67,193

Converted	(222,163)	(B)	$	11.5	(74,053)	(B)	$	6.6	N/A
Vested	N/A				N/A				(2,608)	$	(0.1)
Forfeited	(31,944)				(2,116)				(12,546)
Units/shares outstanding at 12/31/20	612,262		$	5.4	79,002		$	2.7	124,919	$	4.0
Units/shares fully vested at 12/31/20	236,990		$	5.4	79,002		$	2.7	1,752	$	0.1


OG&E	Performance Units								Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
(Dollars in millions)	Number of Units		Aggregate Intrinsic Value		Number of Units		Aggregate Intrinsic Value		Number of Shares		Aggregate Intrinsic Value
Units/shares outstanding at 12/31/19	227,679				53,977				25,005
Granted	67,975	(A)			—				22,665
Converted	(77,799)	(B)	$	4.0	(25,931)	(B)	$	2.3	N/A
Vested	N/A				N/A				(1,113)		$	—
Forfeited	(28,985)				(1,969)				(11,100)
Employee migration	(6,507)	(C)			(842)	(C)			(1,327)	(C)
Units/shares outstanding at 12/31/20	182,363		$	1.7	25,235		$	0.8	34,130		$	1.1
Units/shares fully vested at 12/31/20	75,693		$	1.7	25,235		$	0.8	1,114		$	—

(B)These amounts represent performance units that vested at December 31, 2019 which were settled in March 2020.

(C)Due to certain employees transferring between OG&E and OGE Energy.

Schedule of Nonvested Share Activity [Table Text Block]

The following tables present a summary of the activity for the Registrants' non-vested performance units and restricted stock units for the year ended December 31, 2020.


OGE Energy	Performance Units							Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
	Number of Units		Weighted-Average Grant Date Fair Value		Number of Units	Weighted-Average Grant Date Fair Value		Number of Shares	Weighted-Average Grant Date Fair Value
Units/shares non-vested at 12/31/19	442,654		$	41.43	81,118	$	31.03	72,880	$	41.66
Granted	201,552	(A)	$	38.03	—	$	—	67,193	$	43.69

Vested	(236,990)		$	36.86	(79,002)	$	31.03	(2,608)	$	40.30
Forfeited	(31,944)		$	41.15	(2,116)	$	31.03	(12,546)	$	42.60
Units/shares non-vested at 12/31/20	375,272		$	42.51	—	$	—	124,919	$	42.69


OG&E	Performance Units								Restricted Stock Units
	Total Shareholder Return				Earnings Per Share
	Number of Units		Weighted-Average Grant Date Fair Value		Number of Units		Weighted-Average Grant Date Fair Value		Number of Shares		Weighted-Average Grant Date Fair Value
Units/shares non-vested at 12/31/19	149,880		$	41.31	28,046		$	31.03	25,005		$	41.62
Granted	67,975	(A)	$	38.03	—		$	—	22,665		$	43.69
Vested	(75,693)		$	36.86	(25,235)		$	31.03	(1,113)		$	40.59
Forfeited	(28,985)		$	41.12	(1,969)		$	31.03	(11,100)		$	42.60
Employee migration	(6,507)	(B)	$	40.26	(842)	(B)	$	31.03	(1,327)	(B)	$	42.76
Units/shares non-vested at 12/31/20	106,670		$	42.49	—		$	—	34,130		$	42.67

(B)Due to certain employees transferring between OG&E and OGE Energy.

Fair Value of Vested Performance Units and Restricted Stock [Table Text Block]

The following table presents a summary of the Registrants' fair value for vested performance units and restricted stock units.


	OGE Energy						OG&E
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018
Performance units:
Total shareholder return	$	8.7	$	9.3	$	5.9	$	2.8	$	3.2	$	2.1
Earnings per share	$	2.5	$	5.2	$	4.9	$	0.8	$	0.9	$	1.7
Restricted stock units	$	0.1	$	0.1	$	0.1	$	0.1	$	—	$	—

Schedule of Unrecognized Compensation Cost, Nonvested Awards [Table Text Block]


	OGE Energy			OG&E
December 31, 2020	Unrecognized Compensation Cost (In millions)		Weighted Average to be Recognized (In years)	Unrecognized Compensation Cost (In millions)		Weighted Average to be Recognized (In years)

Performance units - total shareholder return	$	7.1	1.62	$	1.8	1.64


Restricted stock units	1.6		1.65	0.4		1.68
Total unrecognized compensation cost	$	8.7		$	2.2

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Taxes [Abstract]

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

The following table presents the components of income tax expense (benefit).


	OGE Energy						OG&E
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018
Provision (benefit) for current income taxes:
Federal	$	8.4	$	(6.4)	$	(1.9)	$	(3.8)	$	(7.9)	$	(12.4)
State	0.5		5.1		(4.4)		(0.6)		4.1		(4.1)
Total provision (benefit) for current income taxes	8.9		(1.3)		(6.3)		(4.4)		(3.8)		(16.5)
Provision (benefit) for deferred income taxes, net:
Federal	(105.2)		48.5		74.7		45.7		37.7		53.7
State	(31.1)		(17.4)		3.7		(6.6)		(13.8)		2.7
Total provision (benefit) for deferred income taxes, net	(136.3)		31.1		78.4		39.1		23.9		56.4
Deferred federal investment tax credits, net	—		—		0.1		—		—		0.1
Total income tax expense (benefit)	$	(127.4)	$	29.8	$	72.2	$	34.7	$	20.1	$	40.0

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The following table presents a reconciliation of the statutory tax rates to the effective income tax rate.


	OGE Energy						OG&E
Year Ended December 31	2020		2019		2018		2020		2019		2018
Statutory federal tax rate	21.0	%	21.0	%	21.0	%	21.0	%	21.0	%	21.0	%
Impairment of OGE Energy's investment in Enable (A)	31.6		—		—		—		—		—
Remeasurement of state deferred tax liabilities	0.9		(0.8)		(0.4)		—		—		—

Executive compensation limitation	0.2		0.2		0.2		—		—		—
Other	0.1		(0.7)		0.4		0.1		(0.6)		(0.1)
Federal renewable energy credit (B)	(5.0)		(6.0)		(5.1)		(5.4)		(7.6)		(6.9)
Amortization of net unfunded deferred taxes	(4.4)		(4.5)		(2.1)		(4.8)		(5.6)		(2.9)
State income taxes, net of federal income tax benefit	(1.4)		(1.2)		0.4		(1.6)		(1.8)		(0.2)
Stock-based compensation	(0.3)		(1.2)		—		—		—		—
401(k) dividends	(0.4)		(0.4)		(0.3)		—		—		—
Federal deferred tax revaluation	—		—		0.4		—		—		—

Effective income tax rate	42.3	%	6.4	%	14.5	%	9.3	%	5.4	%	10.9	%

(B)Represents credits primarily associated with the production from OG&E's wind farms.

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

The following table presents the components of Deferred Income Taxes at December 31, 2020 and 2019.
















	OGE Energy				OG&E
December 31 (In millions)	2020		2019		2020		2019
Deferred income tax liabilities, net:
Accelerated depreciation and other property related differences	$	1,721.2	$	1,656.8	$	1,721.2	$	1,656.8

Investment in Enable	302.6		478.2		—		—
Regulatory assets	52.3		28.4		52.3		28.4
Pension Plan	3.9		4.1		27.4		24.5
Bond redemption-unamortized costs	2.0		2.2		2.0		2.2
Derivative instruments	1.7		1.6		—		—


Federal tax credits	(236.6)		(238.0)		(236.6)		(238.0)
Income taxes recoverable from customers, net	(221.8)		(229.9)		(221.8)		(229.9)
State tax credits	(204.4)		(185.8)		(189.0)		(170.8)
Regulatory liabilities	(81.0)		(68.1)		(81.0)		(68.1)
Postretirement medical and life insurance benefits	(22.4)		(23.3)		(15.3)		(16.0)
Asset retirement obligations	(20.3)		(19.2)		(20.3)		(19.2)
Net operating losses	(12.0)		(16.6)		(1.4)		(5.7)
Accrued liabilities	(9.6)		(10.7)		(5.2)		(4.3)
Deferred federal investment tax credits	(2.7)		(1.8)		(2.7)		(1.8)
Accrued vacation	(2.2)		(2.1)		(1.6)		(1.6)
Other	(1.4)		0.4		(6.5)		(4.7)
Uncollectible accounts	(0.7)		(0.4)		(0.7)		(0.4)

Total deferred income tax liabilities, net	$	1,268.6	$	1,375.8	$	1,020.8	$	951.4

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

The following table presents a reconciliation of the Registrants' total gross unrecognized tax benefits as of the years ended December 31, 2020, 2019 and 2018.


(In millions)	2020		2019		2018
Balance at January 1	$	20.7	$	20.7	$	20.7
Tax positions related to current year:
Additions	1.2		—		—


Balance at December 31	$	21.9	$	20.7	$	20.7

Summary of Tax Credit Carryforwards [Table Text Block]

The following table presents a summary of these carry forwards.


	OGE Energy				OG&E
(In millions)	Carry Forward Amount		Deferred Tax Asset		Carry Forward Amount		Deferred Tax Asset		Earliest Expiration Date

State operating loss	$	268.0	$	12.0	$	21.5	$	1.4	2030
Federal tax credits	$	236.6	$	236.6	$	236.6	$	236.6	2032
State tax credits:
Oklahoma investment tax credits	$	205.6	$	162.3	$	186.1	$	147.0	N/A
Oklahoma capital investment board credits	$	12.7	$	12.7	$	12.7	$	12.7	N/A
Oklahoma zero emission tax credits	$	37.2	$	29.3	$	37.2	$	29.3	2021
Louisiana inventory credits	$	0.2	$	0.1	$	—	$	—	2021

N/A - not applicable

Common Equity (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

The following table presents the calculation of basic and diluted earnings (loss) per share for OGE Energy.


(In millions except per share data)	2020		2019		2018
Net income (loss)	$	(173.7)	$	433.6	$	425.5
Average common shares outstanding:
Basic average common shares outstanding	200.1		200.1		199.7
Effect of dilutive securities:
Contingently issuable shares (performance and restricted stock units)	—		0.6		0.8
Diluted average common shares outstanding	200.1		200.7		200.5
Basic earnings (loss) per average common share	$	(0.87)	$	2.17	$	2.13
Diluted earnings (loss) per average common share	$	(0.87)	$	2.16	$	2.12
Anti-dilutive shares excluded from earnings per share calculation	0.3		—		—

Long-Term Debt (Tables)

12 Months Ended

Dec. 31, 2020

Long-term Debt, Unclassified [Abstract]

Schedule of Long-term Debt Instruments [Table Text Block]


Series			Date Due	Amount
				(In millions)
0.28%	-	5.35%	Garfield Industrial Authority, January 1, 2025	$	47.0
0.33%	-	4.31%	Muskogee Industrial Authority, January 1, 2025	32.4
0.28%	-	5.35%	Muskogee Industrial Authority, June 1, 2027	56.0
Total (redeemable during next 12 months)				$	135.4

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Schedule of Line of Credit Facilities [Table Text Block]

Short-Term Debt and Credit Facilities (Tables)

12 Months Ended

Dec. 31, 2020

Short-term Debt [Abstract]

The following table presents information regarding the Registrants' revolving credit agreements at December 31, 2020.


	Aggregate		Amount		Weighted-Average
Entity	Commitment		Outstanding (A)		Interest Rate			Expiration
	(In millions)
OGE Energy (B)	$	450.0	$	95.0	0.25	%	(D)	March 8, 2024	(F)
OG&E (C)(E)	450.0		0.4		1.00	%	(D)	March 8, 2024	(F)
Total	$	900.0	$	95.4	0.25	%

(A)Includes direct borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit at December 31, 2020.

(B)This bank facility is available to back up OGE Energy's commercial paper borrowings and to provide revolving credit borrowings. This bank facility can also be used as a letter of credit facility.

(C)This bank facility is available to back up OG&E's commercial paper borrowings and to provide revolving credit borrowings. This bank facility can also be used as a letter of credit facility.

(D)Represents the weighted-average interest rate for the outstanding borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit.

Retirement Plans and Postretirement Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2020

Retirement Plans and Postretirement Benefit Plans [Abstract]

Schedule of Accumulated Benefit Obligations in Excess of Fair Value of Plan Assets [Table Text Block]

These amounts have been recorded in Accrued Benefit Obligations with the offset in Accumulated Other Comprehensive Loss (except OG&E's portion, which is recorded as a regulatory asset as discussed in Note 1) in the balance sheets. The amounts in Accumulated Other Comprehensive Loss and those recorded as a regulatory asset represent a net periodic benefit cost to be recognized in the statements of income in future periods. The benefit obligation for OGE Energy's Pension Plan and the Restoration of Retirement Income Plan represents the projected benefit obligation, while the benefit obligation for the postretirement benefit plans represents the accumulated postretirement benefit obligation. The accumulated postretirement benefit obligation for OGE Energy's Pension Plan and Restoration of Retirement Income Plan differs from the projected benefit obligation in that the former includes no assumption about future compensation levels.


	OGE Energy								OG&E
	Pension Plan				Restoration of Retirement Income Plan				Pension Plan				Restoration of Retirement Income Plan
December 31 (In millions)	2020		2019		2020		2019		2020		2019		2020		2019
Change in benefit obligation
Beginning obligations	$	616.1	$	615.9	$	10.3	$	9.6	$	462.0	$	453.6	$	6.1	$	6.0
Service cost	13.2		12.9		0.8		0.5		9.2		9.0		0.1		0.2
Interest cost	17.0		20.7		0.2		0.4		12.6		15.6		0.1		0.2
Plan settlements	(42.8)		(83.1)		(5.3)		(1.2)		(33.5)		(45.6)		(4.5)		(0.9)
Plan amendments	—		—		—		0.3		—		—		—		—
Plan curtailments	—		—		0.2		—		—		—		—		—
Special termination benefits	7.6		—		—		—		5.1		—		—		—

Actuarial losses	57.7		64.3		1.6		0.7		41.0		42.1		1.2		0.6
Benefits paid	(14.2)		(14.6)		—		—		(12.3)		(12.7)		—		—
Ending obligations	$	654.6	$	616.1	$	7.8	$	10.3	$	484.1	$	462.0	$	3.0	$	6.1

Change in plans' assets
Beginning fair value	$	530.3	$	522.8	$	—	$	—	$	399.1	$	387.6	$	—	$	—
Actual return on plans' assets	77.0		85.2		—		—		57.0		64.8		—		—
Employer contributions	20.0		20.0		5.3		1.2		10.0		5.0		4.5		0.9
Plan settlements	(42.8)		(83.1)		(5.3)		(1.2)		(33.5)		(45.6)		(4.5)		(0.9)

Benefits paid	(14.2)		(14.6)		—		—		(12.3)		(12.7)		—		—
Ending fair value	$	570.3	$	530.3	$	—	$	—	$	420.3	$	399.1	$	—	$	—
Funded status at end of year	$	(84.3)	$	(85.8)	$	(7.8)	$	(10.3)	$	(63.8)	$	(62.9)	$	(3.0)	$	(6.1)
Accumulated postretirement benefit obligation	$	610.8	$	563.3	$	6.9	$	8.1	$	454.7	$	425.8	$	2.9	$	4.8


	OGE Energy				OG&E
	Postretirement Benefit Plans				Postretirement Benefit Plans
December 31 (In millions)	2020		2019		2020		2019
Change in benefit obligation
Beginning obligations	$	136.5	$	135.8	$	104.7	$	104.8
Service cost	0.2		0.2		0.2		0.2
Interest cost	4.2		5.6		3.2		4.3

Plan curtailments	4.0		—		3.1		—
Participants' contributions	3.3		4.1		2.4		3.0
Actuarial losses	7.3		2.9		4.5		2.2
Benefits paid	(11.0)		(12.1)		(8.6)		(9.8)
Ending obligations	$	144.5	$	136.5	$	109.5	$	104.7

Change in plans' assets
Beginning fair value	$	47.0	$	45.3	$	41.9	$	40.6
Actual return on plans' assets	1.2		4.6		1.1		4.0
Employer contributions	7.1		5.1		5.9		4.1

Participants' contributions	3.3		4.1		2.4		3.0
Benefits paid	(11.0)		(12.1)		(8.6)		(9.8)
Ending fair value	$	47.6	$	47.0	$	42.7	$	41.9
Funded status at end of year	$	(96.9)	$	(89.5)	$	(66.8)	$	(62.8)

Schedule of Defined Benefit Plans Disclosures [Table Text Block]


	OGE Energy												OG&E
	Pension Plan						Restoration of Retirement Income Plan						Pension Plan						Restoration of Retirement Income Plan
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018		2020		2019		2018		2020		2019		2018
Service cost	$	13.2	$	12.9	$	14.9	$	0.8	$	0.5	$	0.4	$	9.2	$	9.0	$	9.8	$	0.1	$	0.2	$	0.2
Interest cost	17.0		20.7		23.8		0.2		0.4		0.3		12.6		15.6		17.6		0.1		0.2		0.2
Expected return on plan assets	(37.6)		(36.1)		(44.1)		—		—		—		(27.9)		(27.6)		(33.1)		—		—		—

Amortization of net loss	17.1		17.3		16.2		0.5		0.5		0.7		12.1		12.9		12.1		0.4		0.3		0.5
Plan curtailments	—		—		—		0.2		—		—		—		—		—		—		—		—
Special termination benefits	7.6		—		—		—		—		—		5.1		—		—		—		—		—
Amortization of unrecognized prior service cost (A)	—		—		—		—		—		0.1		—		—		—		—		—		—
Settlement cost	14.1		27.6		25.1		2.7		0.5		1.0		11.4		16.4		19.4		2.4		0.5		0.4
Total net periodic benefit cost	31.4		42.4		35.9		4.4		1.9		2.5		22.5		26.3		25.8		3.0		1.2		1.3
Less: Amount paid by unconsolidated affiliates (B)	2.0		2.9		2.5		0.1		0.1		0.1
Plus: Amount allocated from OGE Energy (B)													5.9		4.5		5.7		1.3		0.5		1.2
Net periodic benefit cost	$	29.4	$	39.5	$	33.4	$	4.3	$	1.8	$	2.4	$	28.4	$	30.8	$	31.5	$	4.3	$	1.7	$	2.5

(B)"Amount paid by unconsolidated affiliates" is only applicable to OGE Energy. "Amount allocated from OGE Energy" is only applicable to OG&E.



Year Ended December 31 (In millions)	2020		2019		2018
Decrease of pension expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	(13.8)	$	(16.1)	$	(14.1)
Deferral of pension expense related to pension settlement, curtailment and special termination benefits charges:
Oklahoma jurisdiction (A)	$	21.6	$	17.9	$	22.1
Arkansas jurisdiction (A)	$	2.0	$	1.7	$	2.1

(A) Included in the pension regulatory asset or liability in each jurisdiction, as indicated in the regulatory assets and liabilities table in Note 1.


	OGE Energy						OG&E
	Postretirement Benefit Plans						Postretirement Benefit Plans
Year Ended December 31 (In millions)	2020		2019		2018		2020		2019		2018
Service cost	$	0.2	$	0.2	$	0.3	$	0.2	$	0.2	$	0.2
Interest cost	4.2		5.6		5.4		3.2		4.3		4.2
Expected return on plan assets	(1.8)		(1.9)		(2.0)		(1.7)		(1.7)		(1.8)
Amortization of net loss	2.0		2.0		3.8		2.1		2.1		3.8
Plan curtailments	1.5		—		—		1.3		—		—
Amortization of unrecognized prior service cost (A)	(8.4)		(8.4)		(8.4)		(6.1)		(6.1)		(6.1)
Total net periodic benefit cost	(2.3)		(2.5)		(0.9)		(1.0)		(1.2)		0.3
Less: Amount paid by unconsolidated affiliates (B)	(0.7)		(0.6)		(0.5)
Plus: Amount allocated from OGE Energy (B)							(0.5)		(0.6)		(0.7)
Net periodic benefit cost	$	(1.6)	$	(1.9)	$	(0.4)	$	(1.5)	$	(1.8)	$	(0.4)

(A) Unamortized prior service cost is amortized on a straight-line basis over the average remaining service period to the first eligibility age of participants who are expected to receive a benefit and are active at the date of the plan amendment.

(B) "Amount paid by unconsolidated affiliates" is only applicable to OGE Energy. "Amount allocated from OGE Energy" is only applicable to OG&E.


Year Ended December 31 (In millions)	2020		2019		2018
Increase of postretirement expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A)	$	0.2	$	1.0	$	4.4
Deferral of postretirement expense related to postretirement plan curtailment charges:
Oklahoma jurisdiction (A)	$	1.4	$	—	$	—
Arkansas jurisdiction (A)	$	0.1	$	—	$	—

(A) Included in the pension regulatory asset or liability in each jurisdiction, as indicated in the regulatory assets and liabilities table in Note 1.

Schedule of Capitalized Pension and Postretirement Cost [Table Text Block]


	OGE Energy						OG&E
(In millions)	2020		2019		2018		2020		2019		2018
Capitalized portion of net periodic pension benefit cost	$	3.8	$	3.6	$	3.8	$	3.1	$	3.0	$	3.2
Capitalized portion of net periodic postretirement benefit cost	$	0.2	$	0.2	$	0.2	$	0.1	$	0.1	$	0.1

Schedule of Assumptions Used [Table Text Block]

Rate Assumptions


	Pension Plan and Restoration of Retirement Income Plan						Postretirement Benefit Plans
Year Ended December 31	2020		2019		2018		2020		2019		2018
Assumptions to determine benefit obligations:
Discount rate	2.30	%	3.15	%	4.20	%	2.45	%	3.25	%	4.30	%
Rate of compensation increase	4.20	%	4.20	%	4.20	%	N/A		N/A		N/A
Interest crediting rate	3.50	%	4.00	%	4.00	%	N/A		N/A		N/A




Assumptions to determine net periodic benefit cost:
Discount rate	2.88	%	3.63	%	3.73	%	3.25	%	4.30	%	3.70	%
Expected return on plan assets	7.50	%	7.50	%	7.50	%	4.00	%	4.00	%	4.00	%
Rate of compensation increase	4.20	%	4.20	%	4.20	%	N/A		N/A		N/A
Interest crediting rate	4.00	%	4.00	%	4.00	%	N/A		N/A		N/A

N/A - not applicable

Projected Benefit Obligation Funded Status Thresholds [Table Text Block]


Projected Benefit Obligation Funded Status Thresholds	<90%	95%	100%	105%	110%	115%	120%
Fixed income	50%	58%	65%	73%	80%	85%	90%
Equity	50%	42%	35%	27%	20%	15%	10%
Total	100%	100%	100%	100%	100%	100%	100%

Pension Plan Equity Asset Allocation Table [Table Text Block]

Within the portfolio's overall allocation to equities, the funds are allocated according to the guidelines in the following table.


Asset Class	Target Allocation	Minimum	Maximum
Domestic Large Cap Equity	40%	35%	60%
Domestic Mid-Cap Equity	15%	5%	25%
Domestic Small-Cap Equity	25%	5%	30%
International Equity	20%	10%	30%

Schedule of Allocation of Plan Assets [Table Text Block]


(In millions)	December 31, 2020		Level 1		Level 3
Group retiree medical insurance contract	$	33.4	$	—	$	33.4

Mutual fund	10.8		10.8		—

Money market fund	3.4		3.4		—
Total OGE Energy plan investments	$	47.6	$	14.2	$	33.4
Plan investments attributable to affiliates	(4.9)
Total OG&E plan investments	$	42.7


(In millions)	December 31, 2019		Level 1		Level 3
Group retiree medical insurance contract	$	34.8	$	—	$	34.8

Mutual funds	10.9		10.9		—

Money market fund	1.2		1.2		—
Total OGE Energy plan investments	$	46.9	$	12.1	$	34.8
Plan investments attributable to affiliates	(5.0)
Total OG&E plan investments	$	41.9

Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets [Table Text Block]

The following table presents a reconciliation of the postretirement benefit plans' investments that are measured at fair value on a recurring basis using significant unobservable inputs (Level 3).


Year Ended December 31 (In millions)	2020
Group retiree medical insurance contract:
Beginning balance	$	34.8
Claims paid	(3.7)
Investment fees	(0.1)
Interest income	0.8
Net unrealized gains related to instruments held at the reporting date	0.6
Dividend income	0.6
Realized gains	0.4
Ending balance	$	33.4

Schedule of Expected Benefit Payments [Table Text Block]


(In millions)	OGE Energy		OG&E
2021	$	164.2	$	123.9
2022	$	43.3	$	33.1
2023	$	42.5	$	31.9
2024	$	44.2	$	32.3
2025	$	41.1	$	29.3
After 2025	$	203.6	$	141.1


(In millions)	OGE Energy		OG&E
2021	$	11.9	$	9.4
2022	$	11.8	$	9.3
2023	$	11.4	$	8.9
2024	$	10.0	$	7.7
2025	$	9.5	$	7.3
After 2025	$	40.9	$	31.0

Defined Benefit Plan, Plan Assets, Category


(In millions)	December 31, 2020		Level 1		Level 2		Net Asset Value (A)
Common stocks	$	252.3	$	252.3	$	—	$	—
U.S. Treasury notes and bonds (B)	134.3		134.3		—		—
Mortgage- and asset-backed securities	29.3		—		29.3		—
Corporate fixed income and other securities	116.6		—		116.6		—
Commingled fund (C)	25.4		—		—		25.4
Foreign government bonds	4.6		—		4.6		—
U.S. municipal bonds	1.8		—		1.8		—

Money market fund	8.8		—		—		8.8
Mutual fund	9.2		9.2		—		—
Preferred stocks	0.6		0.6		—		—
U.S. Treasury futures:


Cash collateral	0.7		0.7		—		—
Forward contracts:
Receivable (foreign currency)	0.1		—		0.1		—

Total Pension Plan investments	583.7		$	397.1	$	152.4	$	34.2
Receivable from broker for securities sold	0.2
Interest and dividends receivable	2.2
Payable to broker for securities purchased	(15.8)
Total OGE Energy Pension Plan assets	$	570.3
Pension Plan investments attributable to affiliates	(150.0)
Total OG&E Pension Plan assets	$	420.3

(B)This category represents U.S. Treasury notes and bonds with a Moody's Investors Service rating of Aaa and Government Agency Bonds with a Moody's Investors Service rating of A1 or higher.

(C)This category represents units of participation in a commingled fund that primarily invested in stocks of international companies and emerging markets.


(In millions)	December 31, 2019		Level 1		Level 2		Net Asset Value (A)

Common stocks	$	202.0	$	202.0	$	—	$	—


U.S. Treasury notes and bonds (B)	134.8		134.8		—		—
Mortgage- and asset-backed securities	45.8		—		45.8		—


Corporate fixed income and other securities	130.5		—		130.5		—

Commingled fund (C)	23.9		—		—		23.9
Foreign government bonds	3.0		—		3.0		—
U.S. municipal bonds	1.1		—		1.1		—

Money market fund	2.4		—		—		2.4

Mutual fund	7.5		7.5		—		—
Preferred stocks	0.7		0.7		—		—
Futures:
U.S. Treasury futures (receivable)	22.9		—		22.9		—
U.S. Treasury futures (payable)	(10.9)		—		(10.9)		—
Cash collateral	0.6		0.6		—		—
Forward contracts:
Receivable (foreign currency)	0.1		—		0.1		—

Total Pension Plan investments	564.4		$	345.6	$	192.5	$	26.3

Interest and dividends receivable	2.4
Payable to broker for securities purchased	(36.5)
Total OGE Energy Pension Plan assets	$	530.3
Pension Plan investments attributable to affiliates	(131.2)
Total OG&E Pension Plan assets	$	399.1

(B)This category represents U.S. Treasury notes and bonds with a Moody's Investors Service rating of Aaa and Government Agency Bonds with a Moody's Investors Service rating of A1 or higher.

(C)This category represents units of participation in a commingled fund that primarily invested in stocks of international companies and emerging markets.

Report of Business Segments (Tables)

12 Months Ended

Dec. 31, 2020

Segment Reporting [Abstract]

Schedule of Segment Reporting Information, by Segment [Table Text Block]

The following tables present the results of OGE Energy's business segments for the years ended December 31, 2020, 2019 and 2018.


2020	Electric Utility		Natural Gas Midstream Operations		Other Operations		Eliminations		Total
(In millions)
Operating revenues	$	2,122.3	$	—	$	—	$	—	$	2,122.3
Cost of sales	644.6		—		—		—		644.6
Other operation and maintenance	464.4		1.7		(3.3)		—		462.8
Depreciation and amortization	391.3		—		—		—		391.3
Taxes other than income	97.2		0.4		3.8		—		101.4
Operating income (loss)	524.8		(2.1)		(0.5)		—		522.2
Equity in losses of unconsolidated affiliates (A)	—		(668.0)		—		—		(668.0)
Other income (expense)	4.1		(2.9)		3.6		(1.6)		3.2
Interest expense	154.8		—		5.3		(1.6)		158.5
Income tax expense (benefit)	34.7		(158.0)		(4.1)		—		(127.4)
Net income (loss)	$	339.4	$	(515.0)	$	1.9	$	—	$	(173.7)
Investment in unconsolidated affiliates	$	—	$	374.3	$	23.1	$	—	$	397.4
Total assets	$	10,489.0	$	378.1	$	116.4	$	(264.7)	$	10,718.8
Capital expenditures	$	650.5	$	—	$	—	$	—	$	650.5

(A) In March 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Notes 5 and 7.


2019	Electric Utility		Natural Gas Midstream Operations		Other Operations		Eliminations		Total
(In millions)
Operating revenues	$	2,231.6	$	—	$	—	$	—	$	2,231.6
Cost of sales	786.9		—		—		—		786.9
Other operation and maintenance	492.5		2.8		(3.5)		—		491.8
Depreciation and amortization	355.0		—		—		—		355.0
Taxes other than income	89.5		0.4		3.7		—		93.6
Operating income (loss)	507.7		(3.2)		(0.2)		—		504.3
Equity in earnings of unconsolidated affiliates	—		113.9		—		—		113.9
Other income (expense)	3.1		(8.6)		2.2		(3.6)		(6.9)
Interest expense	140.5		—		11.0		(3.6)		147.9
Income tax expense (benefit)	20.1		20.7		(11.0)		—		29.8
Net income	$	350.2	$	81.4	$	2.0	$	—	$	433.6


Investment in unconsolidated affiliates	$	—	$	1,132.9	$	18.6	$	—	$	1,151.5
Total assets	$	10,076.6	$	1,135.4	$	107.0	$	(294.7)	$	11,024.3
Capital expenditures	$	635.5	$	—	$	—	$	—	$	635.5


2018	Electric Utility		Natural Gas Midstream Operations		Other Operations		Eliminations		Total
(In millions)
Operating revenues	$	2,270.3	$	—	$	—	$	—	$	2,270.3
Cost of sales	892.5		—		—		—		892.5
Other operation and maintenance	473.8		1.4		(0.6)		—		474.6
Depreciation and amortization	321.6		—		—		—		321.6
Taxes other than income	88.2		0.6		3.2		—		92.0
Operating income (loss)	494.2		(2.0)		(2.6)		—		489.6
Equity in earnings of unconsolidated affiliates	—		152.8		—		—		152.8
Other income (expense)	25.6		(4.9)		(3.4)		(6.0)		11.3
Interest expense	151.8		—		10.2		(6.0)		156.0
Income tax expense (benefit)	40.0		37.1		(4.9)		—		72.2
Net income (loss)	$	328.0	$	108.8	$	(11.3)	$	—	$	425.5


Investment in unconsolidated affiliates	$	—	$	1,166.6	$	10.9	$	—	$	1,177.5
Total assets	$	9,704.5	$	1,169.8	$	184.8	$	(310.5)	$	10,748.6
Capital expenditures	$	573.6	$	—	$	—	$	—	$	573.6

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Abstract]

Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block]

The following table presents the Registrants' future purchase obligations and commitments estimated for the next five years.


(In millions)	2021		2022		2023		2024		2025		Total
Purchase obligations and commitments:
Minimum purchase commitments	$	72.5	$	50.4	$	50.4	$	36.7	$	25.9	$	235.9
Expected wind purchase commitments	55.2		55.6		56.0		56.6		56.9		280.3
Long-term service agreement commitments	2.4		2.4		7.9		35.1		31.2		79.0


Total purchase obligations and commitments	$	130.1	$	108.4	$	114.3	$	128.4	$	114.0	$	595.2

Schedule of Wind Power Purchases [Table Text Block]

The following table presents OG&E's wind power purchase contracts.

Company

Location

Original Term of Contract

Expiration of Contract

MWs

CPV Keenan

Woodward County, OK

20 years

2030

152.0

Edison Mission Energy

Dewey County, OK

20 years

2031

130.0

NextEra Energy

Blackwell, OK

20 years

2032

60.0

The following table presents a summary of OG&E's wind power purchases for the years ended December 31, 2020, 2019 and 2018.


Year Ended December 31 (In millions)	2020		2019		2018
CPV Keenan	$	27.5	$	27.2	$	27.0
Edison Mission Energy	22.8		23.1		21.7
NextEra Energy	7.0		7.4		6.8
FPL Energy (A)	—		—		2.1
Total wind power purchased	$	57.3	$	57.7	$	57.6

(A)OG&E's purchased power contract with FPL Energy for 50 MWs expired in 2018.

Schedule II (Tables)

12 Months Ended

Dec. 31, 2020

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Schedule II Valuation and Qualifying Accounts [Table Text Block]

SCHEDULE II - Valuation and Qualifying Accounts


			Additions
Description	Balance at Beginning of Period		Charged to Costs and Expenses		Deductions (A)		Balance at End of Period
(In millions)
Balance at December 31, 2018
Reserve for Uncollectible Accounts	$	1.5	$	3.4	$	3.2	$	1.7
Balance at December 31, 2019
Reserve for Uncollectible Accounts	$	1.7	$	2.2	$	2.4	$	1.5
Balance at December 31, 2020
Reserve for Uncollectible Accounts	$	1.5	$	3.0	$	1.9	$	2.6

(A)Uncollectible accounts receivable written off, net of recoveries.

Summary of Significant Accounting Policies Regulated Operations (Details) - USD ($)
$ in Millions

Dec. 31, 2020

Dec. 31, 2019

Schedule of Regulatory Assets and Liabilities [Line Items]

Fuel clause under recoveries

$ 0.0

$ 39.5

Fuel clause over recoveries

28.6

4.8

19.8

48.7

415.6

306.0

35.1

29.0

Schedule of Regulatory Assets and Liabilities [Line Items]

$ 1,188.9

1,223.5

CenterPoint [Member]

50.00%

Schedule of Regulatory Assets and Liabilities [Line Items]

SPP Cost Tracker Rider Over Recovery [Member]

50.00%

Schedule of Regulatory Assets and Liabilities [Line Items]

Reserve for Tax Refund [Member]

^[1]

$ 0.0

2.6

Schedule of Regulatory Assets and Liabilities [Line Items]

Income taxes recoverable from customers, net [Member]

^[1]

0.8

12.7

Schedule of Regulatory Assets and Liabilities [Line Items]

Accrued removal obligations [Member]

867.4

899.2

Schedule of Regulatory Assets and Liabilities [Line Items]

Other Regulatory Liabilities [Member]

316.8

318.5

Schedule of Regulatory Assets and Liabilities [Line Items]

^[1]

4.2

6.9

Oklahoma demand program rider over recovery

4.7

5.8

Schedule of Regulatory Assets and Liabilities [Line Items]

SPP cost tracker under recovery [Member]

^[1]

1.5

2.0

Schedule of Regulatory Assets and Liabilities [Line Items]

Benefit obligations regulatory asset [Member]

^[2]

7.0

0.0

Schedule of Regulatory Assets and Liabilities [Line Items]

Deferred storm expenses [Member]

164.9

167.2

Schedule of Regulatory Assets and Liabilities [Line Items]

Schedule of Regulatory Assets and Liabilities [Line Items]

158.8

65.5

Smart Grid [Member]

Unamortized loss on reacquired debt [Member]

11.2

18.4

Schedule of Regulatory Assets and Liabilities [Line Items]

Deferred Pension Expenses [Member]

9.7

10.6

Schedule of Regulatory Assets and Liabilities [Line Items]

Dry Scrubber Regulatory Asset [Member]

9.3

8.0

Schedule of Regulatory Assets and Liabilities [Line Items]

Other Regulatory Assets [Member]

19.7

20.6

Schedule of Regulatory Assets and Liabilities [Line Items]

^[2]

8.4

5.5

Schedule of Regulatory Assets and Liabilities [Line Items]

11.1

13.4

Pension tracker [Member]

Schedule of Regulatory Assets and Liabilities [Line Items]

18.1

2.3

Frontier Plant

Schedule of Regulatory Assets and Liabilities [Line Items]

6.4

0.0

COVID-19 Impact

Generation Capacity Replacement rider

6.4

0.0

Schedule of Regulatory Assets and Liabilities [Line Items]

^[2]

$ 4.4

$ 3.7

[1]	Included in Other Current Liabilities in the balance sheets.
[2]	Included in Other Current Assets in the balance sheets.

Summary of Significant Accounting Policies Accounting Records (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Regulatory Assets, Current	$ 19.8	$ 48.7
Regulatory Assets, Noncurrent	415.6	306.0
Deferred Storm and Property Reserve Deficiency, Current	2.7
Regulatory Liability, Current	35.1	29.0
Pension Plans, Defined Benefit [Member] \| Defined Benefit Plans Income Loss [Member]
Components of Benefit Obligation Regulatory Asset	147.3	160.5
Other Postretirement Benefit Plans, Defined Benefit [Member] \| Defined Benefit Plans Income Loss [Member]
Components of Benefit Obligation Regulatory Asset	26.2	23.3
Other Postretirement Benefit Plans, Defined Benefit [Member] \| Prior Service Cost [Member]
Components of Benefit Obligation Regulatory Asset	$ (8.6)	$ (16.6)

Summary of Significant Accounting Policies Allowance for Uncollectible Accounts Receivable (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Allowance for Doubtful Accounts Receivable	$ 2.6	$ 1.5

Summary of Significant Accounting Policies Fuel Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Other	$ 41.2	$ 24.4
OG&E [Member]
Fuel inventories	36.5	46.3
Other	36.9	19.6
Public Utilities, Inventory, Fuel [Member]
Fuel inventories	$ 36.5	$ 46.3

Summary of Significant Accounting Policies Property, Plant and Equipment (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

$ 13,442.2

$ 12,912.7

4,067.6

3,868.1

Public Utilities, Property, Plant and Equipment, Amount of Acquisition Adjustments, Related Accumulated Depreciation

9,374.6

9,044.6

$ 67.3

$ 61.8

McClain Plant [Member]

Jointly Owned Utility Plant, Proportionate Ownership Share

77.00%

^[1]

77.00%

^[2]

$ 257.1

^[1]

$ 254.4

^[2]

96.0

^[1]

83.5

^[2]

Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress

161.1

^[1]

170.9

^[2]

$ 0.1

$ 0.2

Redbud Plant [Member]

Jointly Owned Utility Plant, Proportionate Ownership Share

51.00%

^[1],[3]

51.00%

^[2],[4]

$ 531.8

^[1],[3]

$ 529.9

^[2],[4]

181.9

^[1],[3]

159.0

^[2],[4]

Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress

349.9

^[1],[3]

370.9

^[2],[4]

1.8

1.4

Amount of Acquisition Adjustments

148.3

6.1

0.0

6.1

OG&E [Member]

13,436.1

12,906.6

4,067.6

3,868.1

Capitalized Computer Software, Gross

9,368.5

9,038.5

89.7

71.3

Capitalized Computer Software, Amortization

14.9

11.0

$ 9.6

OG&E [Member] | Total Property Plant and Equipment [Member]

13,436.1

12,906.6

4,067.6

3,868.1

OG&E [Member] | Electric Transmission and Distribution [Member]

9,368.5

9,038.5

4,809.9

4,468.6

1,422.1

1,381.1

OG&E [Member] | Electric Generation Equipment [Member]

3,387.8

3,087.5

4,932.2

^[5]

4,838.6

^[6]

1,713.6

^[5]

1,601.0

^[6]

Amount of Acquisition Adjustments

3,218.6

^[5]

3,237.6

^[6]

148.3

Public Utilities, Property, Plant and Equipment, Amount of Acquisition Adjustments, Related Accumulated Depreciation

67.3

61.8

OG&E [Member] | Electric Transmission [Member]

2,944.6

^[7]

2,901.1

^[8]

591.7

^[7]

565.5

^[8]

Amount of Acquisition Adjustments

2,352.9

^[7]

2,335.6

^[8]

3.3

Public Utilities, Property, Plant and Equipment, Amount of Acquisition Adjustments, Related Accumulated Depreciation

0.9

0.8

OG&E [Member] | Finite-Lived Intangible Assets, Major Class Name [Member]

254.1

225.2

153.9

145.4

OG&E [Member] | Property, Plant and Equipment, Other Types [Member]

100.2

79.8

495.3

473.1

186.3

175.1

Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]

$ 309.0

$ 298.0

[1]	Construction work in progress was $0.1 million and $1.8 million for the McClain and Redbud Plants, respectively.
[2]	Construction work in progress was $0.2 million and $1.4 million for the McClain and Redbud Plants, respectively.
[3]	This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $67.3 million.
[4]	This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $61.8 million.
[5]	This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $67.3 million.
[6]	This amount includes a plant acquisition adjustment of $148.3 million and accumulated amortization of $61.8 million.
[7]	This amount includes a plant acquisition adjustment of $3.3 million and accumulated amortization of $0.9 million.
[8]	This amount includes a plant acquisition adjustment of $3.3 million and accumulated amortization of $0.8 million.

Summary of Significant Accounting Policies Depreciation and Amortization (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Provision for Depreciation Rate	2.60%	2.70%
Projected provision for depreciation in next fiscal year	2.60%
Percent Of Intangible Plant Balance Amortizable	99.00%
Percent of Intangible Plant Balance Amortizable Thereafter	1.00%
Transmission Equipment [Member] \| OG&E [Member]
Amount of Acquisition Adjustments	$ 3.3
Redbud Plant [Member]
Amount of Acquisition Adjustments	$ 148.3	$ 148.3

Summary of Significant Accounting Policies Asset Retirement Obligation (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Balance at January 1

$ 73.5

$ 83.9

Accretion expense

0.5

1.0

Revisions in estimated cash flows

^[1]

5.8

(2.4)

Liabilities settled

^[2]

(0.2)

(9.0)

Balance at December 31

$ 79.6

$ 73.5

[1]	Assumptions changed related to the estimated timing and estimated cost of the removal of asbestos at OG&E's generating facilities.
[2]	Asset retirement obligations were settled for asbestos removal at one of OG&E's generating facilities

Summary of Significant Accounting Policies Enviromental Costs (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Accrued Environmental Loss Contingencies, Noncurrent	$ 25.0	$ 18.7

Summary of Significant Accounting Policies Allowance for Funds Used During Construction (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Public Utilities, Allowance for Funds Used During Construction, Rate	7.30%	7.60%	7.60%

Summary of Significant Accounting Policies Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Accumulated other comprehensive (income) loss

$ (32.1)

$ (27.9)

$ (28.9)

Other Comprehensive Income (Loss), before Reclassifications, Net of Tax

(8.2)

(9.1)

Amounts reclassified from accumulated other comprehensive income (loss)

(3.9)

(3.4)

(3.3)

Amounts reclassified from accumulated other comprehensive income (loss)

2.1

1.5

Amounts Reclassified from Accumulated OCI, Net of Tax and Noncontrolling Interest

4.0

10.1

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax

(4.2)

1.0

(5.7)

2.2

8.6

4.7

Pension Plans, Defined Benefit [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Amounts reclassified from accumulated other comprehensive income (loss)

(6.1)

(12.0)

Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax

^[1]

(5.1)

(4.5)

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax

^[1]

(2.9)

(11.3)

Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax

(8.0)

(15.8)

Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax

(1.9)

(3.8)

Other Postretirement Benefits Plan [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Amounts reclassified from accumulated other comprehensive income (loss)

2.1

1.9

Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax

^[1]

0.1

0.2

Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax

^[1]

2.3

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax

^[1]

0.4

0.0

Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax

2.8

2.5

Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax

0.7

0.6

Defined Benefit Plans Income Loss [Member] | Pension Plans, Defined Benefit [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Accumulated other comprehensive income (loss)

(34.1)

(35.1)

(38.8)

Other comprehensive income before reclassifications

(5.1)

Other Comprehensive Income (Loss), before Reclassifications, Net of Tax

(8.3)

Amounts reclassified from accumulated other comprehensive income (loss)

3.9

3.4

Defined Benefit Plans Income Loss [Member] | Other Postretirement Benefits Plan [Member]

1.0

3.7

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Accumulated other comprehensive income (loss)

1.4

4.2

4.6

Other comprehensive income before reclassifications

(2.4)

Other Comprehensive Income (Loss), before Reclassifications, Net of Tax

(0.2)

Amounts reclassified from accumulated other comprehensive income (loss)

(0.1)

(0.2)

AOCI Attributable to Parent [Member]

(2.8)

(0.4)

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan Prior Service Cost [Member] | Other Postretirement Benefits Plan [Member]

(4.2)

1.0

(5.7)

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Accumulated other comprehensive income (loss)

1.9

3.6

5.3

Other comprehensive income before reclassifications

0.0

Other Comprehensive Income (Loss), before Reclassifications, Net of Tax

0.0

Amounts reclassified from accumulated other comprehensive income (loss)

(1.7)

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

(1.7)

Settlement Cost [Member]

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax

2.2

8.6

Settlement Cost [Member] | Defined Benefit Plans Income Loss [Member] | Other Postretirement Benefits Plan [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax

0.0

Settlement Cost [Member] | Defined Benefit Plan Prior Service Cost [Member] | Pension Plans, Defined Benefit [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax

2.2

8.6

Settlement Cost [Member] | Defined Benefit Plan Prior Service Cost [Member] | Other Postretirement Benefits Plan [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax

0.0

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax

(0.3)

Curtailment | Defined Benefit Plans Income Loss [Member] | Pension Plans, Defined Benefit [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax

0.0

Curtailment | Defined Benefit Plans Income Loss [Member] | Other Postretirement Benefits Plan [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax

(0.3)

Curtailment | Defined Benefit Plan Prior Service Cost [Member] | Other Postretirement Benefits Plan [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax

0.0

Commodity Contract [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

OCI, before Reclassifications, Net of Tax, Attributable to Parent

(0.6)

Other Comprehensive Income (Loss), before Reclassifications, Net of Tax

(0.7)

Amounts reclassified from accumulated other comprehensive income (loss)

0.0

Net current period other comprehensive income (loss)

(0.7)

(0.6)

AOCI, Derivative Qualifying as Hedge, Excluded Component, after Tax

(1.3)

(0.6)

$ 0.0

Commodity Contract [Member] | Settlement Cost [Member]

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax

0.0

$ 0.0

Commodity Contract [Member] | Curtailment

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax

$ 0.0

[1]	These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost (see Note 13 for additional information).

Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer, Excluding Assessed Tax	$ 2,069.8	$ 2,175.5	$ 2,211.7
Provision for Rate Refund [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	3.8	(0.9)	(6.0)
Integrated Market [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	49.6	38.4	48.7
Transmission [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	143.3	148.0	147.4
Other Contracts with Customers [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	30.7	29.1	27.1
Residential [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	842.7	865.8	877.8
Commercial [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	465.6	486.6	500.0
Industrial [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	192.6	217.8	228.9
Oilfield [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	169.2	200.4	190.4
Public Authority [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	172.3	190.3	197.4
Total Retail Customer [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,842.4	$ 1,960.9	$ 1,994.5

Leases, Codification Topic 842 (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Lessee, Operating Lease, Contingent Liability

$ 6.8

Operating Leased Assets [Line Items]

6.4

$ 6.0

$ 4.9

Cash Paid on Operating Leases

6.4

5.6

Operating Lease, Right-of-Use Asset

^[1]

37.6

40.9

Operating Lease, Liability

^[2]

$ 42.3

$ 45.8

Operating Lease, Weighted Average Remaining Lease Term

12 years 6 months

13 years 1 month 6 days

Operating Lease, Weighted Average Discount Rate, Percent

3.90%

Right-of-Use Asset Obtained in Exchange for Operating Lease Liability

$ 1.4

$ 10.7

Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months

6.3

Lessee, Operating Lease, Liability, Payments, Due Year Two

5.7

Lessee, Operating Lease, Liability, Payments, Due Year Three

5.1

Lessee, Operating Lease, Liability, Payments, Due Year Four

3.2

Lessee, Operating Lease, Liability, Payments, Due Year Five

3.0

Lessee, Operating Lease, Liability, Payments, Due after Year Five

31.7

Lessee, Operating Lease, Liability, Payments, Due

55.0

Lessee, Operating Lease, Liability, Undiscounted Excess Amount

12.7

Lessee, Operating Lease, Contingent Liability

6.8

6.4

6.0

4.9

Operating Leased Assets [Line Items]

5.5

5.1

4.1

Cash Paid on Operating Leases

5.5

4.8

Operating Lease, Right-of-Use Asset

^[1]

37.0

39.6

Operating Lease, Liability

^[2]

$ 41.7

$ 44.3

Operating Lease, Weighted Average Remaining Lease Term

12 years 8 months 12 days

13 years 6 months

Operating Lease, Weighted Average Discount Rate, Percent

3.90%

Right-of-Use Asset Obtained in Exchange for Operating Lease Liability

$ 1.4

$ 10.7

Lessee, Operating Lease, Liability, Payments, Due Next Twelve Months

5.7

Lessee, Operating Lease, Liability, Payments, Due Year Two

5.7

Lessee, Operating Lease, Liability, Payments, Due Year Three

5.1

Lessee, Operating Lease, Liability, Payments, Due Year Four

3.2

Lessee, Operating Lease, Liability, Payments, Due Year Five

3.0

Lessee, Operating Lease, Liability, Payments, Due after Year Five

31.7

Lessee, Operating Lease, Liability, Payments, Due

54.4

Lessee, Operating Lease, Liability, Undiscounted Excess Amount

12.7

Schedule of Equity Method Investments [Line Items]

$ 5.5

$ 5.1

$ 4.1

[1]	Included in Property, Plant and Equipment in the Registrants' balance sheets.
[2]	Included in Other Deferred Credits and Other Liabilities in the Registrants' balance sheets.

Investment in Unconsolidated Affiliate (Details) - USD ($)
$ / shares in Units, shares in Millions, $ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Jun. 30, 2020

May 01, 2013

Limited Partner Units Owned

111.0

Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest

25.50%

25.60%

Distribution Made to Limited Partner, Distributions Declared, Per Unit

$ 0.16525

Equity Method Investment, Difference Between Carrying Amount and Underlying Equity

$ 1,332.3

$ 652.5

Equity in earnings (losses) of unconsolidated affiliates

^[1]

(668.0)

^[2]

113.9

$ 152.8

Share Price

$ 30.36

Enable Midstream Partners [Member]

Schedule of Equity Method Investments [Line Items]

Distributions received

$ 91.7

144.0

141.2

Share Price

$ 5.26

Enogex LLC [Member]

Schedule of Equity Method Investments [Line Items]

Increase in fair value of net assets

$ 2,200.0

OGE Holdings [Member]

Schedule of Equity Method Investments [Line Items]

Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest

25.50%

Schedule of Equity Method Investments [Line Items]

Schedule of Equity Method Investments [Line Items]

50.00%

CenterPoint [Member]

Schedule of Equity Method Investments [Line Items]

50.00%

Energy Transfer

Common Stock, Terms of Conversion

0.8595

Natural Gas Midstream Operations [Member]

Schedule of Equity Method Investments [Line Items]

Equity in earnings (losses) of unconsolidated affiliates

$ (668.0)

^[2]

$ 113.9

$ 152.8

[1]

[2]

In March 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Notes 5 and 7.

Investment in Unconsolidated Affiliate Summarized Balance Sheet Information of Equity Method Investment (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Summarized Financial Information of Equity Method Investment [Line Items]
Assets, Current	$ 428.5	$ 430.2
Liabilities, Current	697.4	657.9
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Summarized Financial Information of Equity Method Investment [Line Items]
Assets, Current	381.0	389.0
Assets, Noncurrent	11,348.0	11,877.0
Liabilities, Current	582.0	780.0
Liabilities, Noncurrent	$ 4,052.0	$ 4,077.0

Sum of the carrying amounts as of the balance sheet date of all assets that are expected to be realized in cash, sold, or consumed within one year (or the normal operating cycle, if longer). Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Sum of the carrying amounts as of the balance sheet date of all assets that are expected to be realized in cash, sold or consumed after one year or beyond the normal operating cycle, if longer.

Total obligations incurred as part of normal operations that are expected to be paid during the following twelve months or within one business cycle, if longer.

Amount of obligation due after one year or beyond the normal operating cycle, if longer.

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Investment in Unconsolidated Affiliate Summarized Income Statement of Equity Method Investment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Operating Income	$ 465.0	$ 569.0	$ 648.0
Operating revenues	2,122.3	2,231.6	2,270.3
Net income (loss)	(173.7)	433.6	425.5
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Schedule of Equity Method Investments [Line Items]
Operating revenues	2,463.0	2,960.0	3,431.0
Cost of Revenue	965.0	1,279.0	1,819.0
Net income (loss)	$ 52.0	$ 360.0	$ 485.3

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Schedule of Equity Method Investments [Line Items]

Investment in Unconsolidated Affiliate Reconciliation of Equity in Earnings of Unconsolidated Affiliates (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest

25.50%

25.60%

Proportionate Unconsolidated Affiliate Net Income

$ 13.2

$ 91.8

$ 124.4

Amortization of basis difference and dilution recognition

^[1]

98.8

22.1

28.4

Equity Method Investment, Other than Temporary Impairment

(780.0)

0.0

^[2]

(668.0)

^[3]

113.9

152.8

Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]

(173.7)

433.6

425.5

Schedule of Equity Method Investments [Line Items]

Natural Gas Midstream Operations [Member]

52.0

360.0

485.3

Schedule of Equity Method Investments [Line Items]

(668.0)

^[3]

113.9

152.8

Schedule of Equity Method Investments [Line Items]

$ (515.0)

$ 81.4

$ 108.8

OGE Holdings [Member]

Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest

25.50%

Schedule of Equity Method Investments [Line Items]

Amortization of basis difference and dilution recognition

^[4]

$ 100.2

[1]	Includes loss on dilution, net of proportional basis difference recognition.
[2]	For the year ended December 31, 2020, Enable recorded a $225.0 million impairment on its SESH equity method investment. Enable estimated the fair value of this equity method investment was below the carrying value at September 30, 2020 and concluded the decline in value was other than temporary due to the expiration of a transportation contract and the current status of renewal negotiations. The impairment ran through OGE Energy's portion of Enable net income and was offset by basis differences that flow through the amortization of basis difference and dilution recognition line item above.
[3]	In March 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Notes 5 and 7.
[4]	Includes proportional basis difference recognition due to dilution.

Related Party Disclosures (Details) - USD ($) $ in Millions	12 Months Ended
Related Party Disclosures (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Expected Settlement Charge	$ 19.0
Excluding Fuel Purchases [Member]
Related Party Transaction [Line Items]
Accounts receivable - unconsolidated affiliates	2.0	$ 0.8
Og and E [Member]
Related Party Transaction [Line Items]
Dividends, Common Stock	325.0		$ 185.0
Og and E [Member] \| Retained Earnings
Related Party Transaction [Line Items]
Dividends, Common Stock	(325.0)	0.0	185.0
Enable Midstream Partners [Member] \| Og and E [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	15.1	15.9	16.3
Enable Midstream Partners [Member] \| Og and E [Member] \| Natural Gas Transportation [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	32.8	41.2	37.9
Enable Midstream Partners [Member] \| Og and E [Member] \| Natural Gas Purchases [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	2.7	(6.0)	(3.2)
Enable Midstream Partners [Member] \| OGE Energy [Member] \| Operating Costs Charged [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party	0.4	0.5	0.6
Enable Midstream Partners [Member] \| OGE Energy [Member] \| Employment Costs [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party	17.3	23.2	27.5
Og and E [Member] \| OGE Energy [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party	$ 140.6	$ 149.8	$ 140.9

Fair Value Measurements Carrying and Fair Value Amounts (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	$ 3,494.4	$ 3,195.2
OG&E Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	3,349.6	3,050.3
Long-Term Debt, Fair Value	4,182.1	3,500.4
OG&E Industrial Authority Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	135.4	135.4
Long-Term Debt, Fair Value	135.4	135.4
OG&E Tinker Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total long-term debt	9.4	9.5
Long-Term Debt, Fair Value	10.7	10.0
Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	$ 0.0	$ 0.0

Stock Based Compensation (Details) - USD ($)
$ / shares in Units, $ in Millions

12 Months Ended

Sep. 30, 2020

Mar. 31, 2020

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of Shares Authorized

7,400,000

Tax Benefit from Compensation Expense

$ 2.5

$ 3.6

$ 3.4

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

247,252

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

247,252

Minimum payout range

0.00%

Maximum payout range

200.00%

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

247,252

Treasury Stock, Shares, Acquired

$ 8.7

405,000

Treasury Stock Acquired, Average Cost Per Share

$ 33.14

$ 38.04

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Tax Benefit from Compensation Expense

$ 0.8

$ 1.3

$ 1.2

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]

Performance Units Related to Earnings Per Share [Member]

$ 2.2

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

87,308

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

$ 0

$ 31.03

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number

79,002

155,171

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

87,308

Equity Instruments Other than Options, Converted in Period

^[1]

(74,053)

Equity Instruments Other than Options, Forfeited in Period

(2,116)

Equity Instruments Other than Options, Converted, Aggregrate Intrinsic Value

79,002

$ 6.6

Equity Instruments Other than Options, Vested in Period, Aggregate Intrinsic Value

(2.7)

Equity Instruments Other than Options, Outstanding, Aggregrate Intrinsic Value

$ 2.7

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]

Equity Instruments Other than Options, Nonvested, Number, Beginning Balance

81,118

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

87,308

Equity Instruments Other than Options, Vested in Period

(79,002)

Equity Instruments Other than Options, Forfeited in Period

(2,116)

Equity Instruments Other than Options, Nonvested, Number, Ending Balance

81,118

Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value

$ 0

$ 31.03

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

$ 31.03

Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value

31.03

Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value

$ 31.03

Fair Value of Vested Performance Units and Restricted Stock

$ 2.5

$ 5.2

$ 4.9

Performance Units Related to Earnings Per Share [Member] | Og and E [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

30,649

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

$ 0

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number

25,235

53,977

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

30,649

Equity Instruments Other than Options, Converted in Period

^[1]

(25,931)

Equity Instruments Other than Options, Forfeited in Period

(1,969)

^[2]

(842)

Equity Other Than Options, Employee Migration, Weighted Average Grant Date Fair Value

25,235

$ 31.03

Equity Instruments Other than Options, Converted, Aggregrate Intrinsic Value

$ 2.3

Equity Instruments Other than Options, Vested in Period, Aggregate Intrinsic Value

(0.8)

Equity Instruments Other than Options, Outstanding, Aggregrate Intrinsic Value

$ 0.8

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]

Equity Instruments Other than Options, Nonvested, Number, Beginning Balance

28,046

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

30,649

Equity Instruments Other than Options, Vested in Period

(25,235)

Equity Instruments Other than Options, Forfeited in Period

(1,969)

Equity Instruments Other than Options, Nonvested, Number, Ending Balance

^[2]

(842)

28,046

Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value

$ 0

$ 31.03

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value

31.03

Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value

$ 31.03

Fair Value of Vested Performance Units and Restricted Stock

$ 0.8

$ 0.9

$ 1.7

Total Shareholder Return [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

201,552

^[3]

208,647

261,916

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

$ 38.03

$ 47.00

$ 36.86

Expected Dividend Rate

3.50%

4.00%

3.60%

Expected Volatility Rate

15.00%

17.00%

19.00%

Risk Free Interest Rate

1.17%

2.47%

2.38%

Expected Term

2 years 10 months 6 days

2 years 10 months 9 days

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number

612,262

664,817

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

201,552

^[3]

208,647

261,916

Equity Instruments Other than Options, Converted in Period

^[1]

(222,163)

Equity Instruments Other than Options, Forfeited in Period

(31,944)

Equity Instruments Other than Options, Converted, Aggregrate Intrinsic Value

236,990

$ 11.5

Equity Instruments Other than Options, Vested in Period, Aggregate Intrinsic Value

(5.4)

Equity Instruments Other than Options, Outstanding, Aggregrate Intrinsic Value

$ 5.4

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]

Equity Instruments Other than Options, Nonvested, Number, Beginning Balance

442,654

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

201,552

^[3]

208,647

261,916

Equity Instruments Other than Options, Vested in Period

(236,990)

Equity Instruments Other than Options, Forfeited in Period

(31,944)

Equity Instruments Other than Options, Nonvested, Number, Ending Balance

375,272

442,654

Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value

$ 42.51

$ 41.43

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

38.03

$ 47.00

$ 36.86

Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value

36.86

Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value

$ 41.15

Fair Value of Vested Performance Units and Restricted Stock

$ 8.7

$ 9.3

$ 5.9

Total Compensation Cost Not yet Recognized, Period for Recognition

$ 7.1

1 year 7 months 13 days

Total Shareholder Return [Member] | Og and E [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

67,975

^[4]

68,396

91,940

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

$ 38.03

$ 47.00

$ 36.86

Expected Dividend Rate

3.50%

4.00%

3.60%

Expected Volatility Rate

15.00%

17.00%

19.00%

Risk Free Interest Rate

1.17%

2.47%

2.38%

Expected Term

2 years 10 months 6 days

2 years 10 months 9 days

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number

182,363

227,679

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

67,975

^[4]

68,396

91,940

Equity Instruments Other than Options, Converted in Period

^[1]

(77,799)

Equity Instruments Other than Options, Forfeited in Period

(28,985)

^[2]

(6,507)

Equity Other Than Options, Employee Migration, Weighted Average Grant Date Fair Value

75,693

$ 40.26

Equity Instruments Other than Options, Converted, Aggregrate Intrinsic Value

$ 4.0

Equity Instruments Other than Options, Vested in Period, Aggregate Intrinsic Value

(1.7)

Equity Instruments Other than Options, Outstanding, Aggregrate Intrinsic Value

$ 1.7

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]

Equity Instruments Other than Options, Nonvested, Number, Beginning Balance

149,880

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

67,975

^[4]

68,396

91,940

Equity Instruments Other than Options, Vested in Period

(75,693)

Equity Instruments Other than Options, Forfeited in Period

(28,985)

Equity Instruments Other than Options, Nonvested, Number, Ending Balance

^[2]

(6,507)

106,670

149,880

Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value

$ 42.49

$ 41.31

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

38.03

$ 47.00

$ 36.86

Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value

36.86

Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value

$ 41.12

Fair Value of Vested Performance Units and Restricted Stock

$ 2.8

$ 3.2

$ 2.1

Total Compensation Cost Not yet Recognized, Period for Recognition

$ 1.8

1 year 7 months 20 days

Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Shares [Member] | Og and E [Member]

$ 8.9

13.0

13.3

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Restricted Stock [Member]

2.6

4.5

4.6

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

$ 0.9

$ 0.1

67,193

75,929

826

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

$ 43.69

$ 41.71

$ 36.28

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number

124,919

72,880

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

67,193

75,929

826

Equity Instruments Other than Options, Forfeited in Period

(12,546)

Equity Instruments Other than Options, Vested in Period, Aggregate Intrinsic Value

1,752

$ (0.1)

Equity Instruments Other than Options, Outstanding, Aggregrate Intrinsic Value

$ 4.0

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]

Equity Instruments Other than Options, Nonvested, Number, Beginning Balance

72,880

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

67,193

75,929

826

Equity Instruments Other than Options, Vested in Period

(2,608)

Equity Instruments Other than Options, Forfeited in Period

(12,546)

Equity Instruments Other than Options, Nonvested, Number, Ending Balance

124,919

72,880

Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value

$ 42.69

$ 41.66

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

43.69

$ 41.71

$ 36.28

Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value

40.30

Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value

$ 42.60

Fair Value of Vested Performance Units and Restricted Stock

$ 0.1

Total Compensation Cost Not yet Recognized, Period for Recognition

$ 1.6

1 year 7 months 24 days

Restricted Stock [Member] | Og and E [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

$ 0.4

$ 0.0

22,665

26,141

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

$ 43.69

$ 41.63

$ 0

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward]

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Outstanding, Number

34,130

25,005

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

22,665

26,141

Equity Instruments Other than Options, Forfeited in Period

(11,100)

^[2]

(1,327)

Equity Other Than Options, Employee Migration, Weighted Average Grant Date Fair Value

1,114

$ 42.76

Equity Instruments Other than Options, Vested in Period, Aggregate Intrinsic Value

$ 0.0

Equity Instruments Other than Options, Outstanding, Aggregrate Intrinsic Value

$ 1.1

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]

Equity Instruments Other than Options, Nonvested, Number, Beginning Balance

25,005

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

22,665

26,141

Equity Instruments Other than Options, Vested in Period

(1,113)

Equity Instruments Other than Options, Forfeited in Period

(11,100)

Equity Instruments Other than Options, Nonvested, Number, Ending Balance

^[2]

(1,327)

34,130

25,005

Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value

$ 42.67

$ 41.62

Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

43.69

$ 41.63

$ 0

Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value

40.59

Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value

$ 42.60

Fair Value of Vested Performance Units and Restricted Stock

$ 0.1

$ 0.0

Total Compensation Cost Not yet Recognized, Period for Recognition

$ 0.4

1 year 8 months 4 days

Stock Compensation Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Stock Compensation Plan [Member] | Og and E [Member]

$ 9.8

13.9

13.4

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Units Related to Earnings Per Share [Member] | Performance Shares [Member]

3.0

4.9

4.6

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Units Related to Earnings Per Share [Member] | Performance Shares [Member] | Og and E [Member]

1.0

4.3

5.1

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Total Shareholder Return [Member] | Performance Shares [Member]

0.3

1.5

1.8

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Total Shareholder Return [Member] | Performance Shares [Member] | Og and E [Member]

7.9

8.7

8.2

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

$ 2.3

$ 3.0

$ 2.8

[1]	These amounts represent performance units that vested at December 31, 2019 which were settled in March 2020.
[2]	Due to certain employees transferring between OG&E and OGE Energy.
[3]	For performance units, this represents the target number of performance units granted. Actual number of performance units earned, if any, is dependent upon performance and may range from zero percent to 200 percent of the target.
[4]	For performance units, this represents the target number of performance units granted. Actual number of performance units earned, if any, is dependent upon performance and may range from zero percent to 200 percent of the target.

Income Taxes (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Current Federal Tax Expense (Benefit)

$ 1,188.9

$ 1,223.5

8.4

(6.4)

$ (1.9)

Current State and Local Tax Expense (Benefit)

0.5

5.1

(4.4)

Current Income Tax Expense (Benefit)

8.9

(1.3)

(6.3)

Deferred Federal Income Tax Expense (Benefit)

(105.2)

48.5

74.7

Deferred State and Local Income Tax Expense (Benefit)

(31.1)

(17.4)

3.7

Deferred Income Tax Expense (Benefit)

(136.3)

31.1

78.4

Investment Tax Credit

0.0

0.1

Income Tax Expense (Benefit)

$ (127.4)

$ 29.8

$ 72.2

Statutory federal tax rate

21.00%

Federal deferred tax revaluation

0.00%

0.40%

Federal renewable energy credit (B)

^[1]

(5.00%)

(6.00%)

(5.10%)

Remeasurement of state deferred tax liabilities

0.90%

(0.80%)

(0.40%)

401(k) dividends

(0.40%)

(0.30%)

State income taxes, net of federal income tax benefit

(1.40%)

(1.20%)

0.40%

Effective Income Tax Rate Reconciliation, Executive Compensation Limitation, Percent

0.20%

Amortization of net unfunded deferred taxes

(4.40%)

(4.50%)

(2.10%)

Effective income tax rate

0.10%

(0.70%)

0.40%

42.30%

6.40%

14.50%

Accrued liabilities

$ (9.6)

$ (10.7)

Accrued vacation

(2.2)

(2.1)

Uncollectible accounts

(0.7)

(0.4)

Accelerated depreciation and other property related differences

1,721.2

1,656.8

Investment in Enable

302.6

478.2

Income taxes recoverable from customers, net

52.3

28.4

(221.8)

(229.9)

Pension Plan

3.9

4.1

Bond redemption-unamortized costs

2.0

2.2

Derivative instruments

1.7

1.6

(236.6)

(238.0)

Postretirement medical and life insurance benefits

(204.4)

(185.8)

(22.4)

(23.3)

Net operating losses

(12.0)

(16.6)

Asset retirement obligations

(81.0)

(68.1)

(20.3)

(19.2)

Deferred federal investment tax credits

(2.7)

(1.8)

Total deferred income tax liabilities, net

(1.4)

0.4

1,268.6

1,375.8

Unrecognized Tax Benefits

21.9

20.7

$ 20.7

Current year additions

1.2

0.0

$ 0.0

Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued

0.0

Effective Income Tax Rate Reconciliation, Tax Contingency, Percent

$ 236.6

$ 238.0

Stock-based compensation

(0.30%)

(1.20%)

0.00%

^[2]

31.60%

0.00%

Deferred Tax Asset [Member]

Unrecognized Tax Benefits

$ 17.6

State operating loss [Member]

Operating Loss Carryforwards

268.0

Deferred Tax Assets, Operating Loss Carryforwards, State and Local

12.0

Federal tax credits [Member]

(236.6)

236.6

Oklahoma investment tax credits [Member]

236.6

(162.3)

Oklahoma capital investment board credits [Member]

205.6

(12.7)

Oklahoma zero emission tax credits [Member]

12.7

(29.3)

Louisiana inventory credits

37.2

(0.1)

Research and Development Credits [Member]

0.2

1.2

Current Federal Tax Expense (Benefit)

1,188.9

$ 1,223.5

(3.8)

(7.9)

$ (12.4)

Current State and Local Tax Expense (Benefit)

(0.6)

4.1

(4.1)

Current Income Tax Expense (Benefit)

(4.4)

(3.8)

(16.5)

Deferred Federal Income Tax Expense (Benefit)

45.7

37.7

53.7

Deferred State and Local Income Tax Expense (Benefit)

(6.6)

(13.8)

2.7

Deferred Income Tax Expense (Benefit)

39.1

23.9

56.4

Investment Tax Credit

0.0

0.1

Income Tax Expense (Benefit)

$ 34.7

$ 20.1

$ 40.0

Statutory federal tax rate

21.00%

Federal deferred tax revaluation

0.00%

Federal renewable energy credit (B)

^[1]

(5.40%)

(7.60%)

(6.90%)

Remeasurement of state deferred tax liabilities

0.00%

401(k) dividends

0.00%

State income taxes, net of federal income tax benefit

(1.60%)

(1.80%)

(0.20%)

Effective Income Tax Rate Reconciliation, Executive Compensation Limitation, Percent

0.00%

Amortization of net unfunded deferred taxes

(4.80%)

(5.60%)

(2.90%)

Effective income tax rate

0.10%

(0.60%)

(0.10%)

9.30%

5.40%

10.90%

Accrued liabilities

$ (5.2)

$ (4.3)

Accrued vacation

(1.6)

Uncollectible accounts

(0.7)

(0.4)

Accelerated depreciation and other property related differences

1,721.2

1,656.8

Investment in Enable

0.0

Income taxes recoverable from customers, net

52.3

28.4

(221.8)

(229.9)

Pension Plan

27.4

24.5

Bond redemption-unamortized costs

2.0

2.2

Derivative instruments

0.0

(236.6)

(238.0)

Postretirement medical and life insurance benefits

(189.0)

(170.8)

(15.3)

(16.0)

Net operating losses

(1.4)

(5.7)

Asset retirement obligations

(81.0)

(68.1)

(20.3)

(19.2)

Deferred federal investment tax credits

(2.7)

(1.8)

Total deferred income tax liabilities, net

(6.5)

(4.7)

1,020.8

951.4

Unrecognized Tax Benefits

17.6

16.4

$ 16.4

Effective Income Tax Rate Reconciliation, Tax Contingency, Percent

$ 236.6

$ 238.0

Stock-based compensation

0.00%

^[2]

0.00%

Og and E [Member] | State operating loss [Member]

Operating Loss Carryforwards

$ 21.5

Deferred Tax Assets, Operating Loss Carryforwards, State and Local

1.4

Og and E [Member] | Federal tax credits [Member]

(236.6)

236.6

Og and E [Member] | Oklahoma investment tax credits [Member]

236.6

(147.0)

Og and E [Member] | Oklahoma capital investment board credits [Member]

186.1

(12.7)

Og and E [Member] | Oklahoma zero emission tax credits [Member]

12.7

(29.3)

Og and E [Member] | Louisiana inventory credits

37.2

0.0

$ 0.0

[1]

Represents credits primarily associated with the production from OG&E's wind farms.

[2]

As further discussed in Note 5, OGE Energy recorded a $780.0 million impairment on its investment in Enable in March 2020, which resulted in a tax benefit being recorded that caused a significant variance to the effective tax rate as compared to the prior year. This variance has been presented in the table as a single line item in order to facilitate comparability of other components of the effective tax rate.

Common Equity Automatic Dividend Reinvestment and Stock Purchase Plan (Details) - Automatic Dividend Reinvestment and Stock Purchase Plan [Member]	12 Months Ended
	Dec. 31, 2020 shares
Stock Issued During Period, Shares, Dividend Reinvestment Plan and Stock Purchase Plan	0
Shares Held in Reserve Related to Dividend Reinvestment Plan and Stock Purchase Plan	4,774,442

Common Equity Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	300	0	0
Net income attributable to OGE Energy	$ (173.7)	$ 433.6	$ 425.5
Basic Average Common Shares Outstanding	200,100	200,100	199,700
Contingently Issuable Shares (Performance and Restricted Stock Units)	0	600	800
Diluted Average Common Shares Outstanding	200,100	200,700	200,500
Earnings Per Share, Basic and Diluted [Abstract]
Basic earnings per average common share attributable to OGE Energy common shareholders	$ (0.87)	$ 2.17	$ 2.13
Diluted earnings per average common share attributable to OGE Energy common shareholders	$ (0.87)	$ 2.16	$ 2.12
Og and E [Member]
Stock Issued During Period, Shares, New Issues	0	0	0
Retained Earnings [Member]
Net income attributable to OGE Energy	$ (173.7)	$ 433.6	$ 425.5

Common Equity Dividends Restriction (Details) shares in Millions, $ in Millions	Dec. 31, 2020 USD ($) shares
Preferred Stock, Shares Outstanding \| shares	0.0
OGE Energy [Member]
Ratio of Consolidated Debt to Consolidated Capitalization	65.00%
Retained Earnings, Restricted	$ 815.0
Retained Earnings, Unrestricted	$ 1,700.0
Og and E [Member]
Ratio of Consolidated Debt to Consolidated Capitalization	65.00%
Retained Earnings, Restricted	$ 842.7
Retained Earnings, Unrestricted	$ 2,100.0

Long-Term Debt (Details) - USD ($) $ in Millions	12 Months Ended
Long-Term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total long-term debt	$ 3,494.4	$ 3,195.2
Percent of Principal Amount Subject to Optional Tender	100.00%
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	$ 0.0
Long-term Debt, Maturities, Repayments of Principal in Year Two	0.0
Long-term Debt, Maturities, Repayments of Principal in Year Three	0.0
Long-term Debt, Maturities, Repayments of Principal in Year Four	0.0
Long-term Debt, Maturities, Repayments of Principal in Year Five	$ 0.0
Garfield Industrial Authority, January 1, 2025 [Member]
Debt Instrument [Line Items]
Date Due	Jan. 01, 2025
Muskogee Industrial Authority, Janaury 1, 2025 [Member]
Debt Instrument [Line Items]
Date Due	Jan. 01, 2025
Muskogee Industrial Authority, June 1, 2027 [Member]
Debt Instrument [Line Items]
Date Due	Jun. 01, 2027
Redeemable during the next 12 months
Debt Instrument [Line Items]
Total long-term debt	$ 135.4
OG&E [Member]
Debt Instrument [Line Items]
Total long-term debt	3,494.4	3,195.2
OG&E [Member] \| Redeemable during the next 12 months \| Garfield Industrial Authority, January 1, 2025 [Member]
Debt Instrument [Line Items]
Long term debt, gross	47.0	47.0
OG&E [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority, Janaury 1, 2025 [Member]
Debt Instrument [Line Items]
Long term debt, gross	32.4	32.4
OG&E [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority, June 1, 2027 [Member]
Debt Instrument [Line Items]
Long term debt, gross	56.0	56.0
Senior Notes [Member] \| OG&E [Member] \| Series Due April 1, 2030
Debt Instrument [Line Items]
Long term debt, gross	$ 300.0	$ 0.0
Debt Instrument, Interest Rate, Stated Percentage	3.25%
Date Due	Apr. 01, 2030
Debt Instrument, Face Amount	$ 300.0
Minimum [Member] \| Redeemable during the next 12 months \| Garfield Industrial Authority, January 1, 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.28%
Minimum [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority, Janaury 1, 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.33%
Minimum [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority, June 1, 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.28%
Maximum [Member] \| Redeemable during the next 12 months \| Garfield Industrial Authority, January 1, 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.35%
Maximum [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority, Janaury 1, 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.31%
Maximum [Member] \| Redeemable during the next 12 months \| Muskogee Industrial Authority, June 1, 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.35%

Short-Term Debt and Credit Facilities (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Short-term debt

$ 95.0

$ 112.0

Weighted Average Interest Rate

Aggregate Commitment

900.0

Amount Outstanding

^[1]

$ 95.4

0.25%

Proceeds from Unsecured Lines of Credit

$ 75.0

Repayments of Unsecured Debt

75.0

Other Commitment

1,000.0

Acceleration of Indebtedness of Credit Facility

100.0

Nonpayment of Uninsured Judgments

100.0

Line of Credit Facility, Current Borrowing Capacity

^[2]

450.0

Weighted Average Interest Rate

Amount Outstanding

^[1],[2]

$ 95.0

^[2],[3]

0.25%

Maturity

^[2],[4]

Mar. 08, 2024

Ratio of Consolidated Debt to Consolidated Capitalization

65.00%

OGE Energy [Member] | Not Extended

Line of Credit Facility, Current Borrowing Capacity

$ 50.0

Maturity

Mar. 08, 2023

OG&E [Member]

Line of Credit Facility, Current Borrowing Capacity

^[5],[6]

$ 450.0

Letters of Credit Outstanding, Amount

^[1],[5],[6]

$ 0.4

Weighted Average Interest Rate

^[3],[5],[6]

1.00%

Maturity

^[4],[5],[6]

Mar. 08, 2024

Intercompany Borrowing Agreement - Maximum Borrowing Capacity

$ 350.0

Period For Which Regulatory Approval Has Been Given to Acquire Short Term Debt

2 years

Short Term Borrowing Capacity That Has Regulatory Approval

$ 800.0

Ratio of Consolidated Debt to Consolidated Capitalization

65.00%

Outstanding Intercompany Borrowings

$ 0.0

[1]	Includes direct borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit at December 31, 2020.
[2]	This bank facility is available to back up OGE Energy's commercial paper borrowings and to provide revolving credit borrowings. This bank facility can also be used as a letter of credit facility.
[3]	Represents the weighted-average interest rate for the outstanding borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit.
[4]	In March 2017, the Registrants entered into unsecured five-year revolving credit agreements totaling $900.0 million ($450.0 million for OGE Energy and $450.0 million for OG&E). Each of the revolving credit facilities contained an option, which could be exercised up to two times, to extend the term of the respective facility for an additional year. In March 2018, the Registrants each utilized one of those extensions to extend the maturity of their respective credit facility from March 8, 2022 to March 8, 2023. In January 2021, the Registrants each utilized the second of those extensions to extend the maturity of their respective credit facility from March 8, 2023 to March 8, 2024. Commitments of a single existing lender with respect to $50.0 million of OGE Energy's credit facility, however, were not extended and, unless the non-extending lender is replaced in accordance with the terms of the credit facility, such commitments will expire March 8, 2023. The non-extending lender is not party to the OG&E facility.
[5]	OG&E has an intercompany borrowing agreement with OGE Energy whereby OG&E has access to up to $350.0 million of OGE Energy's revolving credit amount. This agreement has a termination date of March 8, 2024. At December 31, 2020, there were no intercompany borrowings under this agreement.
[6]	This bank facility is available to back up OG&E's commercial paper borrowings and to provide revolving credit borrowings. This bank facility can also be used as a letter of credit facility.

Retirement Plans and Postretirement Benefit Plans (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Mar. 31, 2021

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Contribution Plan, Employer Matching Contribution, Percent of Match

200.00%

Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay

5.00%

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

$ 40.0

$ 20.0

Ultimate Health Care Cost Trend Rate

4.50%

Expected Future Benefit Payments, Next Twelve Months

$ 164.2

Expected Future Benefit Payments, Year Two

43.3

Expected Future Benefit Payments, Year Three

42.5

Expected Future Benefit Payments, Year Four

44.2

Expected Future Benefit Payments, Year Five

41.1

Expected Future Benefit Payments, Five Fiscal Years Thereafter

203.6

18.2

14.4

$ 13.2

2.2

2.1

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

10.0

5.0

Expected Future Benefit Payments, Next Twelve Months

123.9

Expected Future Benefit Payments, Year Two

33.1

Expected Future Benefit Payments, Year Three

31.9

Expected Future Benefit Payments, Year Four

32.3

Expected Future Benefit Payments, Year Five

29.3

Expected Future Benefit Payments, Five Fiscal Years Thereafter

141.1

14.3

11.0

9.8

Pension Plans, Defined Benefit [Member]

1.8

1.7

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment

(14.2)

(14.6)

0.0

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

654.6

616.1

615.9

13.2

12.9

14.9

17.0

20.7

23.8

Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits

0.0

7.6

0.0

(42.8)

(83.1)

57.7

64.3

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

654.6

616.1

615.9

570.3

530.3

522.8

77.0

85.2

20.0

(42.8)

(83.1)

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

570.3

530.3

522.8

13.2

12.9

14.9

17.0

20.7

23.8

(37.6)

(36.1)

(44.1)

(17.1)

(17.3)

(16.2)

^[1]

0.0

Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits

0.0

7.6

0.0

14.1

27.6

25.1

31.4

42.4

35.9

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

^[2]

2.0

2.9

2.5

29.4

39.5

33.4

(42.8)

(83.1)

Assumptions Used Calculating Benefit Obligation, Discount Rate

$ 3.8

$ 3.6

$ 3.8

2.30%

3.15%

4.20%

Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets

7.50%

Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase

4.20%

Defined Benefit Plan, Benefit Obligation, Benefits Paid

570.3

$ 530.3

$ 522.8

(14.2)

(14.6)

Pension Plans, Defined Benefit [Member] | Og and E [Member]

(610.8)

(563.3)

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

(12.3)

(12.7)

484.1

462.0

453.6

9.2

9.0

$ 9.8

12.6

15.6

17.6

Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits

0.0

5.1

0.0

(33.5)

(45.6)

41.0

42.1

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

484.1

462.0

453.6

420.3

399.1

387.6

57.0

64.8

10.0

5.0

(33.5)

(45.6)

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

420.3

399.1

387.6

9.2

9.0

9.8

12.6

15.6

17.6

(27.9)

(27.6)

(33.1)

(12.1)

(12.9)

(12.1)

0.0

Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits

0.0

5.1

0.0

11.4

16.4

19.4

Amount Attributable to Parent

22.5

26.3

25.8

^[2]

5.9

4.5

5.7

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

28.4

30.8

31.5

(33.5)

(45.6)

3.1

3.0

3.2

Defined Benefit Plan, Benefit Obligation, Benefits Paid

420.3

399.1

387.6

(12.3)

(12.7)

Pension Plans, Defined Benefit [Member] | OKLAHOMA

(454.7)

(425.8)

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Additional Pension Expense to Meet State Requirements

^[3]

21.6

17.9

22.1

(13.8)

^[3]

(16.1)

(14.1)

Pension Plans, Defined Benefit [Member] | ARKANSAS

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member]

^[3]

2.0

1.7

2.1

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Restoration of Retirement Income Plan [Member]

0.0

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment

0.0

0.0

0.3

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

7.8

10.3

9.6

0.8

0.5

0.4

0.2

0.4

0.3

Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits

0.2

0.0

0.0

(5.3)

(1.2)

1.6

0.7

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

7.8

10.3

9.6

0.0

0.0

5.3

1.2

(5.3)

(1.2)

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

0.8

0.5

0.4

0.2

0.4

0.3

0.0

(0.5)

(0.7)

^[1]

0.0

0.1

Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits

0.2

0.0

0.0

2.7

0.5

1.0

4.4

1.9

2.5

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

^[2]

0.1

4.3

1.8

2.4

(5.3)

(1.2)

Defined Benefit Plan, Benefit Obligation, Benefits Paid

0.0

0.0

Restoration of Retirement Income Plan [Member] | Og and E [Member]

(6.9)

(8.1)

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

0.0

3.0

6.1

6.0

0.1

0.2

0.1

0.2

Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits

0.0

0.0

(4.5)

(0.9)

1.2

0.6

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

3.0

6.1

6.0

0.0

0.0

4.5

0.9

(4.5)

(0.9)

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

0.1

0.2

0.1

0.2

0.0

(0.4)

(0.3)

(0.5)

0.0

Defined Benefit Plan, Cost of Providing Special and Contractual Termination Benefits

0.0

0.0

2.4

0.5

0.4

Amount Attributable to Parent

3.0

1.2

1.3

^[2]

1.3

0.5

1.2

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

4.3

1.7

2.5

(4.5)

(0.9)

Defined Benefit Plan, Benefit Obligation, Benefits Paid

0.0

0.0

Other Postretirement Benefits Plan [Member]

(2.9)

(4.8)

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment

(11.0)

(12.1)

0.0

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

144.5

136.5

135.8

0.2

0.3

4.2

5.6

5.4

Defined Benefit Plan, Plan Assets, Contributions by Plan Participant

4.0

0.0

(3.3)

(4.1)

7.3

2.9

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

144.5

136.5

135.8

47.6

47.0

45.3

1.2

4.6

7.1

5.1

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

47.6

47.0

45.3

0.2

0.3

4.2

5.6

5.4

(1.8)

(1.9)

(2.0)

(2.0)

(3.8)

^[1]

(8.4)

(1.5)

0.0

(2.3)

(2.5)

(0.9)

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

^[4]

(0.7)

(0.6)

(0.5)

(1.6)

(1.9)

(0.4)

Assumptions Used Calculating Benefit Obligation, Discount Rate

$ 0.2

2.45%

3.25%

4.30%

Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets

4.00%

Health Care Cost Trend Rate Assumed for Next Fiscal Year

6.75%

Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant

47.6

$ 47.0

$ 45.3

3.3

4.1

Defined Benefit Plan, Benefit Obligation, Benefits Paid

(11.0)

(12.1)

Other Postretirement Benefits Plan [Member] | Og and E [Member]

(96.9)

(89.5)

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

(8.6)

(9.8)

109.5

104.7

104.8

0.2

$ 0.2

3.2

4.3

4.2

Defined Benefit Plan, Plan Assets, Contributions by Plan Participant

3.1

0.0

(2.4)

(3.0)

4.5

2.2

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

109.5

104.7

104.8

42.7

41.9

40.6

1.1

4.0

5.9

4.1

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

42.7

41.9

40.6

0.2

3.2

4.3

4.2

(1.7)

(1.8)

(2.1)

(3.8)

^[1]

(6.1)

(1.3)

0.0

Amount Attributable to Parent

(1.0)

(1.2)

0.3

^[4]

(0.5)

(0.6)

(0.7)

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

(1.5)

(1.8)

(0.4)

0.1

Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant

42.7

41.9

40.6

2.4

3.0

Defined Benefit Plan, Benefit Obligation, Benefits Paid

(8.6)

(9.8)

Other Postretirement Benefits Plan [Member] | OKLAHOMA

(66.8)

(62.8)

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Additional Pension Expense to Meet State Requirements

1.4

0.0

^[5]

0.2

1.0

4.4

Other Postretirement Benefits Plan [Member] | ARKANSAS

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Other Postretirement Benefits Plan [Member] | Fair Value, Inputs, Level 1 [Member]

0.1

0.0

$ 0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

14.2

12.1

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

14.2

12.1

Other Postretirement Benefits Plan [Member] | Fair Value, Inputs, Level 2 [Member]

14.2

12.1

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Other Postretirement Benefits Plan [Member] | Fair Value, Inputs, Level 3 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

33.4

34.8

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

33.4

34.8

Other Postretirement Benefits Plan [Member] | Fair Value, Inputs, Level 1, 2 and 3 [Member]

33.4

34.8

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

47.6

46.9

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

47.6

46.9

Other Postretirement Benefits Plan [Member] | Fair Value, Inputs, Level 1, 2 and 3 [Member] | Og and E [Member]

47.6

46.9

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

42.7

41.9

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

42.7

41.9

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

42.7

$ 41.9

Less Than 90% [Member]

Projected Benefit Obligation Funded Status Thresholds Fixed Income

50.00%

Projected Benefit Obligation Funded Status Thresholds Equity

50.00%

Projected Benefit Obligation Funded Status Thresholds

100.00%

95% [Member]

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Projected Benefit Obligation Funded Status Thresholds Fixed Income

58.00%

Projected Benefit Obligation Funded Status Thresholds Equity

42.00%

Projected Benefit Obligation Funded Status Thresholds

100.00%

100% [Member]

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Projected Benefit Obligation Funded Status Thresholds Fixed Income

65.00%

Projected Benefit Obligation Funded Status Thresholds Equity

35.00%

Projected Benefit Obligation Funded Status Thresholds

100.00%

105% [Member]

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Projected Benefit Obligation Funded Status Thresholds Fixed Income

73.00%

Projected Benefit Obligation Funded Status Thresholds Equity

27.00%

Projected Benefit Obligation Funded Status Thresholds

100.00%

110% [Member]

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Projected Benefit Obligation Funded Status Thresholds Fixed Income

80.00%

Projected Benefit Obligation Funded Status Thresholds Equity

20.00%

Projected Benefit Obligation Funded Status Thresholds

100.00%

115% [Member]

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Projected Benefit Obligation Funded Status Thresholds Fixed Income

85.00%

Projected Benefit Obligation Funded Status Thresholds Equity

15.00%

Projected Benefit Obligation Funded Status Thresholds

100.00%

120% [Member]

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Projected Benefit Obligation Funded Status Thresholds Fixed Income

90.00%

Projected Benefit Obligation Funded Status Thresholds Equity

10.00%

Projected Benefit Obligation Funded Status Thresholds

100.00%

Domestic All-Cap/Large Cap Equity [Member]

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Domestic Mid-Cap Equity [Member]

40.00%

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Domestic Small-Cap Equity [Member]

15.00%

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

International Equity [Member]

25.00%

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Minimum [Member] | Domestic All-Cap/Large Cap Equity [Member]

20.00%

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Minimum [Member] | Domestic Mid-Cap Equity [Member]

35.00%

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Minimum [Member] | Domestic Small-Cap Equity [Member]

5.00%

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Minimum [Member] | International Equity [Member]

5.00%

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Maximum [Member] | Domestic All-Cap/Large Cap Equity [Member]

10.00%

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Maximum [Member] | Domestic Mid-Cap Equity [Member]

60.00%

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Maximum [Member] | Domestic Small-Cap Equity [Member]

25.00%

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Maximum [Member] | International Equity [Member]

30.00%

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

Group Retiree Medical Insurance Contract [Member] | Other Postretirement Benefits Plan [Member]

30.00%

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

33.4

$ 34.8

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

33.4

34.8

Group Retiree Medical Insurance Contract [Member] | Other Postretirement Benefits Plan [Member] | Fair Value, Inputs, Level 1 [Member]

33.4

34.8

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Group Retiree Medical Insurance Contract [Member] | Other Postretirement Benefits Plan [Member] | Fair Value, Inputs, Level 3 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

33.4

34.8

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

33.4

34.8

U.S. common stocks [Member] | Pension Plans, Defined Benefit [Member]

33.4

34.8

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

^[6]

0.0

^[7]

252.3

202.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

252.3

202.0

U.S. common stocks [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

252.3

202.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

252.3

202.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

252.3

202.0

U.S. common stocks [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

252.3

202.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

U.S. treasury notes and bonds [Member] | Pension Plans, Defined Benefit [Member]

0.0

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

^[6],[8]

0.0

^[7],[9]

^[9]

134.3

134.8

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

^[9]

134.3

134.8

U.S. treasury notes and bonds [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

^[9]

134.3

134.8

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

^[9]

134.3

134.8

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

^[9]

134.3

134.8

U.S. treasury notes and bonds [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

^[9]

134.3

134.8

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

^[9]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

^[9]

0.0

Mortgage-backed securities | Pension Plans, Defined Benefit [Member]

^[9]

0.0

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

^[6]

0.0

^[7]

29.3

45.8

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

29.3

45.8

Mortgage-backed securities | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

29.3

45.8

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Mortgage-backed securities | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

29.3

45.8

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

29.3

45.8

Corporate fixed income and other securities [Member] | Pension Plans, Defined Benefit [Member]

29.3

45.8

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

^[6]

0.0

^[7]

116.6

130.5

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

116.6

130.5

Corporate fixed income and other securities [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

116.6

130.5

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Corporate fixed income and other securities [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

116.6

130.5

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

116.6

130.5

Commingled fund [Member] | Pension Plans, Defined Benefit [Member]

116.6

130.5

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

25.4

^[6],[10]

23.9

^[7],[11]

^[11]

25.4

23.9

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

^[11]

25.4

23.9

Commingled fund [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

^[11]

25.4

23.9

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

^[11]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

^[11]

0.0

Commingled fund [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

^[11]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

^[11]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

^[11]

0.0

Foreign government bonds [Member] | Pension Plans, Defined Benefit [Member]

^[11]

0.0

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

^[6]

0.0

^[7]

4.6

3.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

4.6

3.0

Foreign government bonds [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

4.6

3.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Foreign government bonds [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

4.6

3.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

4.6

3.0

Municipal bonds [Member] | Pension Plans, Defined Benefit [Member]

4.6

3.0

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

^[6]

0.0

^[7]

1.8

1.1

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

1.8

1.1

Municipal bonds [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

1.8

1.1

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Municipal bonds [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

1.8

1.1

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

1.8

1.1

Money market funds [Member] | Pension Plans, Defined Benefit [Member]

1.8

1.1

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

8.8

^[6]

2.4

^[7]

8.8

2.4

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

8.8

2.4

Money market funds [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

8.8

2.4

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Money market funds [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Mutual fund [Member] | Pension Plans, Defined Benefit [Member]

0.0

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

^[6]

0.0

^[7]

9.2

7.5

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

9.2

7.5

Mutual fund [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

9.2

7.5

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

9.2

7.5

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

9.2

7.5

Mutual fund [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

9.2

7.5

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Treasury futures, receivable [Member] | Pension Plans, Defined Benefit [Member]

0.0

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

^[7]

0.0

22.9

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

22.9

Treasury futures, receivable [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

22.9

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Treasury futures, receivable [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

22.9

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

22.9

Treasury futures, payable [Member] | Pension Plans, Defined Benefit [Member]

22.9

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

^[7]

0.0

(10.9)

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

(10.9)

Treasury futures, payable [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

(10.9)

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Treasury futures, payable [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

(10.9)

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

(10.9)

Cash collateral [Member] | Pension Plans, Defined Benefit [Member]

(10.9)

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

^[6]

0.0

^[7]

0.7

0.6

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.7

0.6

Cash collateral [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

0.7

0.6

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.7

0.6

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.7

0.6

Cash collateral [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

0.7

0.6

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Receivable (foreign currency) [Member] | Pension Plans, Defined Benefit [Member]

0.0

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

^[6]

0.0

^[7]

0.1

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.1

Receivable (foreign currency) [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

0.1

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Receivable (foreign currency) [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.1

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.1

Preferred stocks (foreign) [Member] | Pension Plans, Defined Benefit [Member]

0.1

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

^[6]

0.0

0.6

0.7

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.6

0.7

Preferred stocks (foreign) [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

0.6

0.7

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.6

0.7

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.6

0.7

Preferred stocks (foreign) [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

0.6

0.7

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.0

Total Plan investments [Member] | Pension Plans, Defined Benefit [Member]

0.0

Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

34.2

^[6]

26.3

^[7]

583.7

564.4

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

583.7

564.4

Total Plan investments [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

583.7

564.4

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

397.1

345.6

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

397.1

345.6

Total Plan investments [Member] | Pension Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

397.1

345.6

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

152.4

192.5

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

152.4

192.5

Receivable from broker for securities sold [Member] | Pension Plans, Defined Benefit [Member]

152.4

192.5

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.2

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

0.2

Interest and dividends receivable [Member] | Pension Plans, Defined Benefit [Member]

0.2

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

2.2

2.4

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

2.2

2.4

Payable to broker for securities purchased [Member] | Pension Plans, Defined Benefit [Member]

2.2

2.4

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

(15.8)

(36.5)

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

(15.8)

(36.5)

Total Plan assets [Member] | Pension Plans, Defined Benefit [Member]

(15.8)

(36.5)

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

570.3

530.3

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

570.3

530.3

Total Plan assets [Member] | Pension Plans, Defined Benefit [Member] | Og and E [Member]

570.3

530.3

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

420.3

399.1

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

420.3

399.1

Plan Assets Attributable to Affiliates | Pension Plans, Defined Benefit [Member]

420.3

399.1

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

(150.0)

(131.2)

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

(150.0)

$ (131.2)

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

$ (150.0)

$ (131.2)

[1]	Unamortized prior service cost is amortized on a straight-line basis over the average remaining service period to the first eligibility age of participants who are expected to receive a benefit and are active at the date of the plan amendment.
[2]	Amount paid by unconsolidated affiliates" is only applicable to OGE Energy. "Amount allocated from OGE Energy" is only applicable to OG&E.
[3]	Included in the pension regulatory asset or liability in each jurisdiction, as indicated in the regulatory assets and liabilities table in Note 1.
[4]	"Amount paid by unconsolidated affiliates" is only applicable to OGE Energy. "Amount allocated from OGE Energy" is only applicable to OG&E.
[5]	Included in the pension regulatory asset or liability in each jurisdiction, as indicated in the regulatory assets and liabilities table in Note 1.
[6]	GAAP allows the measurement of certain investments that do not have a readily determinable fair value at the net asset value. These investments do not consider the observability of inputs; therefore, they are not included within the fair value hierarchy.
[7]	GAAP allows the measurement of certain investments that do not have a readily determinable fair value at the net asset value. These investments do not consider the observability of inputs; therefore, they are not included within the fair value hierarchy.
[8]	This category represents U.S. Treasury notes and bonds with a Moody's Investors Service rating of Aaa and Government Agency Bonds with a Moody's Investors Service rating of A1 or higher.
[9]	This category represents U.S. Treasury notes and bonds with a Moody's Investors Service rating of Aaa and Government Agency Bonds with a Moody's Investors Service rating of A1 or higher.
[10]	This category represents units of participation in a commingled fund that primarily invested in stocks of international companies and emerging markets.
[11]	This category represents units of participation in a commingled fund that primarily invested in stocks of international companies and emerging markets.

Retirement Plans and Postretirement Benefit Plans Postretirement Benefit Plans (Details) - USD ($)
$ in Millions

3 Months Ended

12 Months Ended

Mar. 31, 2021

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2020

Dec. 31, 2019

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

$ 40.0

$ 20.0

Level 3 Asset Value, Beginning of Period

33.4

34.8

0.8

0.6

0.6

0.4

Administrative expenses and charges

(0.1)

Claims paid

(3.7)

Level 3 Asset Value, End of Period

$ 33.4

$ 34.8

Postretirement Plan, Expected Future Benefit Payments, Next Twelve Months

$ 11.9

Postretirement Plan, Expected Future Benefit Payments, Year Two

11.8

Postretirement Plan, Expected Future Benefit Payments, Year Three

11.4

Postretirement Plan, Expected Future Benefit Payments in Year Four

10.0

Postretirement Plan, Expected Future Benefit Payments, Year Five

9.5

Postretirement Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter

40.9

Ultimate Health Care Cost Trend Rate

$ 2.2

$ 2.1

4.50%

Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate

4.00%

3.50%

4.00%

Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate

4.00%

Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay

$ 18.2

$ 14.4

$ 13.2

5.00%

Defined Contribution Plan, Employer Matching Contribution, Percent of Match

200.00%

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value

33.4

$ 33.4

34.8

$ 33.4

$ 34.8

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Claims Paid

3.7

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Administrative Expenses and Charges

0.1

0.6

0.8

0.6

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

10.0

5.0

Postretirement Plan, Expected Future Benefit Payments, Next Twelve Months

9.4

Postretirement Plan, Expected Future Benefit Payments, Year Two

9.3

Postretirement Plan, Expected Future Benefit Payments, Year Three

8.9

Postretirement Plan, Expected Future Benefit Payments in Year Four

7.7

Postretirement Plan, Expected Future Benefit Payments, Year Five

7.3

Postretirement Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter

31.0

1.8

1.7

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

14.3

11.0

9.8

Cash [Member]

1.2

Fair Value, Inputs, Level 1 [Member] | Cash [Member]

1.2

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

1.2

Fair Value, Inputs, Level 3 [Member] | Cash [Member]

1.2

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

0.0

Pension Plan [Member]

654.6

616.1

615.9

13.2

12.9

14.9

17.0

20.7

23.8

(42.8)

(83.1)

57.7

64.3

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

654.6

616.1

615.9

570.3

530.3

522.8

77.0

85.2

20.0

(42.8)

(83.1)

570.3

530.3

522.8

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

$ (84.3)

$ (85.8)

13.2

12.9

14.9

17.0

20.7

23.8

(37.6)

(36.1)

(44.1)

^[1]

0.0

0.0

14.1

27.6

25.1

31.4

42.4

35.9

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

^[2]

2.0

2.9

2.5

29.4

39.5

33.4

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Assumptions Used Calculating Benefit Obligation, Discount Rate

$ 3.8

$ 3.6

$ 3.8

4.20%

2.30%

3.15%

Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate

2.88%

3.63%

3.73%

Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets

7.50%

Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase

4.20%

Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase

4.20%

Defined Benefit Plan, Benefit Obligation, Benefits Paid

$ (14.2)

$ (14.6)

14.2

14.6

Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment

$ 610.8

$ 563.3

0.0

Pension Plan [Member] | Og and E [Member]

0.0

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

484.1

462.0

453.6

9.2

9.0

$ 9.8

12.6

15.6

17.6

(33.5)

(45.6)

41.0

42.1

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

484.1

462.0

453.6

420.3

399.1

387.6

57.0

64.8

10.0

5.0

(33.5)

(45.6)

420.3

399.1

387.6

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

(63.8)

(62.9)

9.2

9.0

9.8

12.6

15.6

17.6

(27.9)

(27.6)

(33.1)

0.0

0.0

11.4

16.4

19.4

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

22.5

26.3

25.8

28.4

30.8

31.5

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Defined Benefit Plan, Benefit Obligation, Benefits Paid

3.1

3.0

3.2

(12.3)

(12.7)

12.3

12.7

454.7

425.8

Pension Plan [Member] | Equity Funds [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

^[3]

25.4

23.9

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

^[3]

25.4

23.9

Pension Plan [Member] | Money market funds [Member]

25.4

^[4],[5]

23.9

^[3],[6]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

8.8

2.4

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

8.8

2.4

Pension Plan [Member] | Total Plan assets [Member]

$ 8.8

^[4]

$ 2.4

^[6]

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

570.3

530.3

Pension Plan [Member] | Total Plan assets [Member] | Og and E [Member]

570.3

530.3

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

420.3

399.1

Pension Plan [Member] | Plan Assets Attributable to Affiliates

420.3

399.1

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

(150.0)

(131.2)

Pension Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Funds [Member]

(150.0)

(131.2)

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

^[3]

0.0

Pension Plan [Member] | Fair Value, Inputs, Level 1 [Member] | Money market funds [Member]

^[3]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Pension Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Equity Funds [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

^[3]

0.0

Pension Plan [Member] | Fair Value, Inputs, Level 2 [Member] | Money market funds [Member]

^[3]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Pension Plan [Member] | Fair Value, Inputs, Level 3 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Other Postretirement Benefit Plans, Defined Benefit [Member]

0.0

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

144.5

136.5

135.8

0.2

0.3

4.2

5.6

5.4

7.3

2.9

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

144.5

136.5

135.8

47.6

47.0

45.3

1.2

4.6

7.1

5.1

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

47.6

47.0

45.3

0.2

0.3

4.2

5.6

5.4

(1.8)

(1.9)

(2.0)

^[1]

(8.4)

(1.5)

0.0

(2.3)

(2.5)

(0.9)

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

^[7]

(0.7)

(0.6)

(0.5)

(1.6)

(1.9)

(0.4)

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Assumptions Used Calculating Benefit Obligation, Discount Rate

$ 0.2

4.30%

2.45%

3.25%

Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate

3.25%

4.30%

3.70%

Health Care Cost Trend Rate Assumed for Next Fiscal Year

6.75%

Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets

4.00%

Defined Benefit Plan, Benefit Obligation, Benefits Paid

$ (11.0)

$ (12.1)

11.0

12.1

Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment

$ 96.9

$ 89.5

0.0

Other Postretirement Benefit Plans, Defined Benefit [Member] | Og and E [Member]

4.0

0.0

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

109.5

104.7

104.8

0.2

$ 0.2

3.2

4.3

4.2

4.5

2.2

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

109.5

104.7

104.8

42.7

41.9

40.6

1.1

4.0

5.9

4.1

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

42.7

41.9

40.6

0.2

3.2

4.3

4.2

(1.7)

(1.8)

^[1]

(6.1)

(1.3)

0.0

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

(1.0)

(1.2)

0.3

(1.5)

(1.8)

(0.4)

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Defined Benefit Plan, Benefit Obligation, Benefits Paid

0.1

(8.6)

(9.8)

8.6

9.8

66.8

62.8

Other Postretirement Benefit Plans, Defined Benefit [Member] | Group Retiree Medical Insurance Contract [Member]

3.1

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

33.4

34.8

Other Postretirement Benefit Plans, Defined Benefit [Member] | U.S. Equity Mutual Funds Investment [Member]

33.4

34.8

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

10.8

10.9

Other Postretirement Benefit Plans, Defined Benefit [Member] | Cash [Member]

10.8

10.9

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

3.4

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member]

3.4

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

14.2

12.1

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Group Retiree Medical Insurance Contract [Member]

14.2

12.1

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Equity Mutual Funds Investment [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

10.8

10.9

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1 [Member] | Cash [Member]

10.8

10.9

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

3.4

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 2 [Member]

3.4

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

33.4

34.8

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Group Retiree Medical Insurance Contract [Member]

33.4

34.8

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

33.4

34.8

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Equity Mutual Funds Investment [Member]

33.4

34.8

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 3 [Member] | Cash [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

0.0

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1, 2 and 3 [Member]

0.0

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

47.6

46.9

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1, 2 and 3 [Member] | Og and E [Member]

47.6

46.9

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

42.7

41.9

Other Postretirement Benefit Plans, Defined Benefit [Member] | Fair Value, Inputs, Level 1, 2 and 3 [Member] | OGE Energy [Member]

42.7

41.9

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

(4.9)

(5.0)

Other Pension Plan [Member]

(4.9)

(5.0)

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

7.8

10.3

9.6

0.8

0.5

0.4

0.2

0.4

0.3

(5.3)

(1.2)

1.6

0.7

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

7.8

10.3

9.6

0.0

0.0

5.3

1.2

(5.3)

(1.2)

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

(7.8)

(10.3)

0.8

0.5

0.4

0.2

0.4

0.3

0.0

^[1]

0.0

0.1

0.2

0.0

2.7

0.5

1.0

4.4

1.9

2.5

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

^[2]

0.1

4.3

1.8

2.4

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Defined Benefit Plan, Benefit Obligation, Benefits Paid

0.0

0.0

Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment

6.9

8.1

0.0

0.3

Other Pension Plan [Member] | Og and E [Member]

0.2

0.0

Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]

3.0

6.1

6.0

0.1

0.2

0.1

0.2

(4.5)

(0.9)

1.2

0.6

Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]

3.0

6.1

6.0

$ 0.0

0.0

0.0

4.5

0.9

(4.5)

(0.9)

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

(3.0)

(6.1)

0.1

0.2

0.1

0.2

0.0

0.0

0.0

2.4

0.5

0.4

Net Periodic Benefit Cost, Net of Unconsolidated Affiliates

3.0

1.2

1.3

4.3

1.7

2.5

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]

Defined Benefit Plan, Benefit Obligation, Benefits Paid

0.0

0.0

$ 2.9

$ 4.8

OKLAHOMA | Pension Plan [Member]

0.0

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

OKLAHOMA | Other Postretirement Benefit Plans, Defined Benefit [Member]

^[8]

21.6

17.9

22.1

Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]

$ 1.4

$ 0.0

[1]	Unamortized prior service cost is amortized on a straight-line basis over the average remaining service period to the first eligibility age of participants who are expected to receive a benefit and are active at the date of the plan amendment.
[2]	Amount paid by unconsolidated affiliates" is only applicable to OGE Energy. "Amount allocated from OGE Energy" is only applicable to OG&E.
[3]	This category represents units of participation in a commingled fund that primarily invested in stocks of international companies and emerging markets.
[4]	GAAP allows the measurement of certain investments that do not have a readily determinable fair value at the net asset value. These investments do not consider the observability of inputs; therefore, they are not included within the fair value hierarchy.
[5]	This category represents units of participation in a commingled fund that primarily invested in stocks of international companies and emerging markets.
[6]	GAAP allows the measurement of certain investments that do not have a readily determinable fair value at the net asset value. These investments do not consider the observability of inputs; therefore, they are not included within the fair value hierarchy.
[7]	"Amount paid by unconsolidated affiliates" is only applicable to OGE Energy. "Amount allocated from OGE Energy" is only applicable to OG&E.
[8]	Included in the pension regulatory asset or liability in each jurisdiction, as indicated in the regulatory assets and liabilities table in Note 1.

Report of Business Segments (Details) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

$ 2,122.3

$ 2,231.6

$ 2,270.3

644.6

786.9

892.5

462.8

491.8

474.6

391.3

355.0

321.6

101.4

93.6

92.0

522.2

504.3

489.6

^[1]

(668.0)

^[2]

113.9

152.8

3.2

(6.9)

11.3

158.5

147.9

156.0

(127.4)

29.8

72.2

(173.7)

433.6

425.5

397.4

1,151.5

1,177.5

10,718.8

11,024.3

10,748.6

Equity Method Investment, Other than Temporary Impairment

650.5

635.5

573.6

780.0

0.0

Electric Utility [Member]

2,122.3

2,231.6

2,270.3

644.6

786.9

892.5

464.4

492.5

473.8

391.3

355.0

321.6

97.2

89.5

88.2

524.8

507.7

494.2

0.0

^[2]

0.0

4.1

3.1

25.6

154.8

140.5

151.8

34.7

20.1

40.0

339.4

350.2

328.0

0.0

10,489.0

10,076.6

9,704.5

Natural Gas Midstream Operations [Member]

650.5

635.5

573.6

0.0

0.0

1.7

2.8

1.4

0.0

0.4

0.6

(2.1)

(3.2)

(2.0)

(668.0)

^[2]

113.9

152.8

(2.9)

(8.6)

(4.9)

0.0

(158.0)

20.7

37.1

(515.0)

81.4

108.8

374.3

1,132.9

1,166.6

378.1

1,135.4

1,169.8

Other Operations [Member]

0.0

0.0

0.0

(3.3)

(3.5)

(0.6)

0.0

3.8

3.7

3.2

(0.5)

(0.2)

(2.6)

0.0

^[2]

0.0

3.6

2.2

(3.4)

5.3

11.0

10.2

(4.1)

(11.0)

(4.9)

1.9

2.0

(11.3)

23.1

18.6

10.9

116.4

107.0

184.8

0.0

Eliminations [Member]

0.0

0.0

0.0

0.0

0.0

0.0

0.0

^[2]

0.0

(1.6)

(3.6)

(6.0)

(1.6)

(3.6)

(6.0)

0.0

0.0

0.0

(264.7)

(294.7)

(310.5)

$ 0.0

[1]

[2]

In March 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Notes 5 and 7.

Commitments and Contingencies (Details)
$ in Millions

12 Months Ended

Dec. 31, 2020

USD ($)

Dec. 31, 2019

USD ($)

Dec. 31, 2018

USD ($)

Operating Leases, Future Minimum Payments Due, Next Twelve Months

$ 130.1

Operating Leases, Future Minimum Payments, Due in Two Years

108.4

Operating Leases, Future Minimum Payments, Due in Three Years

114.3

Operating Leases, Future Minimum Payments, Due in Four Years

128.4

Operating Leases, Future Minimum Payments, Due in Five Years

114.0

Utilities Operating Expense, Purchased Power under Long-term Contracts

595.2

57.3

$ 57.7

$ 57.6

OG&E minimum fuel purchase commitments [Member]

Purchase Obligation, Due in Next Twelve Months

235.9

72.5

Unrecorded Unconditional Purchase Obligation, Due within Two Years

50.4

Unrecorded Unconditional Purchase Obligation, Due within Three Years

50.4

Unrecorded Unconditional Purchase Obligation, Due within Four Years

36.7

Unrecorded Unconditional Purchase Obligation, Due within Five Years

25.9

OG&E expected wind purchase commitments [Member]

Purchase Obligation, Due in Next Twelve Months

280.3

55.2

Unrecorded Unconditional Purchase Obligation, Due within Two Years

55.6

Unrecorded Unconditional Purchase Obligation, Due within Three Years

56.0

Unrecorded Unconditional Purchase Obligation, Due within Four Years

56.6

Unrecorded Unconditional Purchase Obligation, Due within Five Years

56.9

OG&E long-term service agreement commitments [Member]

Purchase Obligation, Due in Next Twelve Months

79.0

2.4

Unrecorded Unconditional Purchase Obligation, Due within Two Years

2.4

Unrecorded Unconditional Purchase Obligation, Due within Three Years

7.9

Unrecorded Unconditional Purchase Obligation, Due within Four Years

35.1

Unrecorded Unconditional Purchase Obligation, Due within Five Years

31.2

OG&E total cogeneration payments [Member]

Utilities Operating Expense, Purchased Power under Long-term Contracts

14.7

112.4

OG&E capacity payments [Member]

Utilities Operating Expense, Purchased Power under Long-term Contracts

7.4

60.0

CPV Keenan [Member]

Utilities Operating Expense, Purchased Power under Long-term Contracts

27.5

27.2

27.0

Edison Mission Energy [Member]

Utilities Operating Expense, Purchased Power under Long-term Contracts

22.8

23.1

21.7

NextEra Energy [Member]

Utilities Operating Expense, Purchased Power under Long-term Contracts

7.0

7.4

6.8

FPL Energy [Member]

Utilities Operating Expense, Purchased Power under Long-term Contracts

^[1]

$ 0.0

$ 2.1

OG&E long-term service agreement commitments [Member] | McClain Plant [Member]

OG&E long-term service agreement commitments [Member] | Redbud Plant [Member]

Factored-Fired Hours

128,000

Factored-Fired Starts

4,800

Additional Factored-Fired Hours

Factored-Fired Hours

144,000

Factored-Fired Starts

4,500

24,000

Maximum [Member]