OGE Energy (OGE) 10-Q 4 Nov 21 2021 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information Document	9 Months Ended
	Sep. 30, 2021shares
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	1-12579
Entity Registrant Name	OGE ENERGY CORP.
Entity Incorporation, State or Country Code	OK
Entity Tax Identification Number	73-1481638
Entity Central Index Key	0001021635
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false
Title of 12(b) Security	Common Stock
Trading Symbol	OGE
Security Exchange Name	NYSE
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Address, Address Line One	321 North Harvey
Entity Address, Address Line Two	P.O. Box 321
Entity Address, City or Town	Oklahoma City
Entity Address, State or Province	OK
Entity Address, Postal Zip Code	73101-0321
City Area Code	405
Local Phone Number	553-3000
Entity Common Stock, Shares Outstanding	200,174,540
OG&E [Member]
Entity Information [Line Items]
Entity File Number	1-1097
Entity Registrant Name	OKLAHOMA GAS AND ELECTRIC COMPANY
Entity Tax Identification Number	73-0382390
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding	40,378,745

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues from contracts with customers	[1]	$ 848.2	$ 687.8	$ 3,033.7	$ 1,600.2
Other revenues		16.2	14.3	38.7	36.7
Operating revenues		864.4	702.1	3,072.4	1,636.9
FUEL, PURCHASED POWER AND DIRECT TRANSMISSION EXPENSE		330.1	209.1	1,876.9	481.5
OPERATING EXPENSES
Other operation and maintenance		115.4	109.7	343.9	347.2
Depreciation and amortization		108.6	100.5	310.2	292.2
Taxes other than income		25.5	24.8	78.5	76.3
Operating expenses		249.5	235	732.6	715.7
OPERATING INCOME		284.8	258	462.9	439.7
OTHER INCOME (EXPENSE)
Equity in earnings (losses) of unconsolidated affiliates	[2]	41.2	15.8	127.9	(703.8)	[3]
Allowance for equity funds used during construction		1.9	1.1	4.8	3.7
Other net periodic benefit expense		(1.6)	(2)	(4.3)	(3.5)
Other income		5.6	5.5	14.9	27
Other expense		(3.8)	(5.4)	(12.5)	(23.9)
Net other income (expense)		43.3	15	130.8	(700.5)
INTEREST EXPENSE
Interest on long-term debt		39.3	38.7	115.5	114.1
Allowance for borrowed funds used during construction		(1)	(0.5)	(2.5)	(1.5)
Interest on short-term debt and other interest charges		1.2	1.6	5.8	6.3
Interest expense		39.5	39.8	118.8	118.9
INCOME (LOSS) BEFORE TAXES		288.6	233.2	474.9	(379.7)
INCOME TAX EXPENSE (BENEFIT)		36.1	55.8	56.8	(151.2)
NET INCOME (LOSS)		$ 252.5	$ 177.4	$ 418.1	$ (228.5)
BASIC AVERAGE COMMON SHARES OUTSTANDING		200.2	200.1	200.1	200.1
DILUTED AVERAGE COMMON SHARES OUTSTANDING		200.4	200.4	200.3	200.1
BASIC EARNINGS (LOSS) PER AVERAGE COMMON SHARE		$ 1.26	$ 0.89	$ 2.09	$ (1.14)
DILUTED EARNINGS (LOSS) PER AVERAGE COMMON SHARE		$ 1.26	$ 0.89	$ 2.09	$ (1.14)
Other Comprehensive Income (Loss), Net of Tax		$ 1.6	$ 2.2	$ 5.8	$ 2.2
Comprehensive Income (Loss), Net of Tax, Attributable to Parent		254.1	179.6	423.9	(226.3)
OG&E [Member]
Revenues from contracts with customers		848.2	687.8	3,033.7	1,600.2
Other revenues		16.2	14.3	38.7	36.7
Operating revenues		864.4	702.1	3,072.4	1,636.9
FUEL, PURCHASED POWER AND DIRECT TRANSMISSION EXPENSE		330.1	209.1	1,876.9	481.5
OPERATING EXPENSES
Other operation and maintenance		115.8	110.1	344.4	348.8
Depreciation and amortization		108.6	100.5	310.2	292.2
Taxes other than income		24.6	23.9	75.3	72.8
Operating expenses		249	234.5	729.9	713.8
OPERATING INCOME		285.3	258.5	465.6	441.6
OTHER INCOME (EXPENSE)
Allowance for equity funds used during construction		1.9	1.1	4.8	3.7
Other net periodic benefit expense		(1.1)	(1.3)	(3.2)	(2.8)
Other income		2.4	1.1	5.2	3.7
Other expense		(0.3)	(0.3)	(1)	(1.7)
Net other income (expense)		2.9	0.6	5.8	2.9
INTEREST EXPENSE
Interest on long-term debt		38.4	38.7	114.2	114.1
Allowance for borrowed funds used during construction		(1)	(0.5)	(2.5)	(1.5)
Interest on short-term debt and other interest charges		0.6	1.3	2.6	3.1
Interest expense		38	39.5	114.3	115.7
INCOME (LOSS) BEFORE TAXES		250.2	219.6	357.1	328.8
INCOME TAX EXPENSE (BENEFIT)		26.4	20.1	37	30.5
NET INCOME (LOSS)		223.8	199.5	320.1	298.3
Other Comprehensive Income (Loss), Net of Tax		0	0	0	0
Comprehensive Income (Loss), Net of Tax, Attributable to Parent		$ 223.8	$ 199.5	$ 320.1	$ 298.3
[1]	In February 2021, Winter Storm Uri resulted in record winter peak demand for electricity and extremely high natural gas and purchased power prices in OG&E's service territory. Operating revenues for the nine months ended September 30, 2021 significantly increased due to increased fuel, purchased power and direct transmission expenses, which are generally recoverable from customers, as a result of Winter Storm Uri. For further discussion, see Note 15 and "Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operation."
[2]	For the three and nine months ended September 30, 2020, Enable recorded a $225.0 million impairment on its SESH equity method investment, which is included in their net loss for each period. 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 (loss) and was offset by basis differences that flow through the amortization of basis difference and dilution recognition line item above.
[3]	In 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Note 4

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Other comprehensive income (loss), net of tax
Net Income (Loss) Attributable to Parent	$ 252.5	$ 177.4	$ 418.1	$ (228.5)
Pension Plan and Restoration of Retirement Income Plan:
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax	0.1	0	0.1	0
Amortization of deferred net loss, net of tax of $0.2, $0.3, $0.6 and $0.9, respectively	0.4	0.9	1.2	2.9
Settlement cost, net of tax of $0.3, $0.5, $1.9 and $0.6, respectively	1.1	1.3	4.8	1.5
Postretirement Benefit Plans:
Amortization of prior service credit, net of tax of ($0.1), ($0.2), ($0.3) and ($0.5), respectively	(0.3)	(0.4)	(1)	(1.2)
Amortization of deferred net gain (loss), net of tax of $0.0, $0.0, $0.0 and $0.0, respectively	0	0	0.1	(0.1)
Other comprehensive gain (loss) from unconsolidated affiliates, net of tax of $0.0, $0.1, $0.1 and ($0.3), respectively	0.3	0.4	0.6	(0.9)
Other comprehensive income (loss), net of tax	1.6	2.2	5.8	2.2
Comprehensive income (loss)	254.1	179.6	423.9	(226.3)
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Noncontrolling Interest	$ 0	$ 0.1	$ 0.1	$ (0.3)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) Parenthetical - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax	$ 0	$ 0	$ 0	$ 0
Pension Plan and Restoration of Retirement Income Plan:
Amortization of deferred net loss	0.2	0.3	0.6	0.9
Postretirement Benefit Plans:
Amortization of prior service cost	(0.1)	(0.2)	(0.3)	(0.5)
Other Comprehensive Income Reclassification Of Defined Benefit Postretirement Plans Net Gain Loss Recognized In Net Periodic Benefit Cost Tax	0	0	0	0
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Noncontrolling Interest	0	0.1	0.1	(0.3)
Pension Plan [Member]
Other Comprehensive Income (Loss), Defined Benefit Plan, Adjustment for Settlement or Curtailment Gain (Loss), Tax	$ 0.3	$ 0.5	$ 1.9	$ 0.6

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Adjustments to reconcile net income (loss) to net cash (used in) provided from operating activities:
Net Income (Loss) Attributable to Parent		$ 418.1	$ (228.5)
Depreciation and amortization		310.2	292.2
Deferred income taxes and investment tax credits, net		40.9	(168.4)
Equity in (earnings) losses of unconsolidated affiliates	[1]	(127.9)	703.8	[2]
Distributions from unconsolidated affiliates		55	73.3
Allowance for equity funds used during construction		(4.8)	(3.7)
Stock-based compensation expense		7.1	6.7
Regulatory assets		(881.5)	(8.5)
Regulatory liabilities		(50)	(48.6)
Other assets		(6.7)	(3.7)
Other liabilities		(41.6)	(39.2)
Change in certain current assets and liabilities:
Accounts receivable and accrued unbilled revenues, net		(99.4)	(62.9)
Increase (Decrease) in Income Taxes Receivable		7.6	10
Fuel, materials and supplies inventories		8.7	(2)
Fuel recoveries		(126.8)	74.3
Other current assets		(4.9)	(6.3)
Accounts payable		(41.4)	(68.6)
Other current liabilities		43.3	5.4
Net cash (used in) provided from operating activities		(494.1)	525.3
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures (less allowance for equity funds used during construction)		(540.6)	(419.7)
Investment in unconsolidated affiliates		(6.3)	(2.4)
Net cash used in investing activities		(546.9)	(422.1)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from Issuance of Long-term Debt		999.6	297.1
Increase (decrease) in short-term debt		288.2	(112)
Payment of long-term debt		(0.1)	(0.1)
Dividends paid on common stock		(242.8)	(234.4)
Net cash provided from (used in) financing activities		1,041.4	(71.2)
NET CHANGE IN CASH AND CASH EQUIVALENTS		0.4	32
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD		1.1	0
CASH AND CASH EQUIVALENTS AT END OF PERIOD		1.5	32
Proceeds from (Payments for) Other Financing Activities		(3.5)	(7.1)
Treasury Stock, Value, Acquired, Cost Method		0	(14.7)
OG&E [Member]
Adjustments to reconcile net income (loss) to net cash (used in) provided from operating activities:
Net Income (Loss) Attributable to Parent		320.1	298.3
Depreciation and amortization		310.2	292.2
Deferred income taxes and investment tax credits, net		32.1	23.9
Allowance for equity funds used during construction		(4.8)	(3.7)
Stock-based compensation expense		1.6	2.2
Regulatory assets		(881.5)	(8.5)
Regulatory liabilities		(50)	(48.6)
Other assets		(0.9)	(3.2)
Other liabilities		(38.2)	(27.6)
Change in certain current assets and liabilities:
Accounts receivable and accrued unbilled revenues, net		(100.8)	(62.4)
Fuel, materials and supplies inventories		8.7	(2)
Fuel recoveries		(126.8)	74.3
Other current assets		(3.2)	(5.8)
Accounts payable		(39.3)	(59.6)
Other current liabilities		36	(0.7)
Net cash (used in) provided from operating activities		(529.6)	478.4
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures (less allowance for equity funds used during construction)		(540.6)	(419.7)
Net cash used in investing activities		(540.6)	(419.7)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from Issuance of Long-term Debt		499.8	297.1
Payment of long-term debt		(0.1)	(0.1)
Net cash provided from (used in) financing activities		1,071.7	(26.7)
NET CHANGE IN CASH AND CASH EQUIVALENTS		1.5	32
CASH AND CASH EQUIVALENTS AT BEGINNING OF PERIOD		0	0
CASH AND CASH EQUIVALENTS AT END OF PERIOD		1.5	32
Increase (Decrease) in Income Taxes Payable		7.2	9.6
Changes In Advances With Parent		87	(248.7)
Proceeds from Contributed Capital		530	0
Payments of Dividends		$ (45)	$ (75)
[1]	For the three and nine months ended September 30, 2020, Enable recorded a $225.0 million impairment on its SESH equity method investment, which is included in their net loss for each period. 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 (loss) and was offset by basis differences that flow through the amortization of basis difference and dilution recognition line item above.
[2]	In 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Note 4

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
CURRENT ASSETS
Cash and cash equivalents	$ 1.5	$ 1.1	$ 32	$ 0
Accounts Receivable, after Allowance for Credit Loss, Current	242.3	157.8
Accrued unbilled revenues	82.5	67.6
Fuel inventories	(35)	(36.5)
Income taxes receivable	0.5	8.1
Materials and supplies, at average cost	111.4	116.2
Fuel clause under recoveries	98.2	0
Other	55.6	41.2
Total current assets	627	428.5
OTHER PROPERTY AND INVESTMENTS
Investment in unconsolidated affiliates	478.9	397.4	376.8
Other	90.8	86.7
Total other property and investments	569.7	484.1
PROPERTY, PLANT AND EQUIPMENT
In service	13,703.9	13,296.7
Construction work in progress	249.3	145.5
Total property, plant and equipment	13,953.2	13,442.2
Less: accumulated depreciation	4,257.3	4,067.6
Property, Plant and Equipment, Net	9,695.9	9,374.6
DEFERRED CHARGES AND OTHER ASSETS
Regulatory assets	1,264.9	415.6
Other	20	16
Total deferred charges and other assets	1,284.9	431.6
TOTAL ASSETS	12,177.5	10,718.8	10,497.6
CURRENT LIABILITIES
Short-term Debt	383.2	95
Accounts payable	243.5	251.5
Dividends payable	82.1	80.5
Customer deposits	80.6	81.1
Accrued taxes	82.8	55.7
Accrued interest	42.5	40.2
Accrued compensation	38.6	31.1
Fuel clause over recoveries	0	28.6
Other	40.6	33.7
Total current liabilities	993.9	697.4
LONG-TERM DEBT	4,495.8	3,494.4
DEFERRED CREDITS AND OTHER LIABILITIES
Accrued benefit obligations	175.2	231.4
Deferred income taxes	1,240.9	1,268.6
Deferred investment tax credits	11	10.9
Regulatory liabilities	1,247.7	1,188.9
Other	198.1	195.4
Total deferred credits and other liabilities	2,872.9	2,895.2
Total liabilities	8,362.6	7,087
COMMITMENTS AND CONTINGENCIES (NOTE 14)
STOCKHOLDERS' EQUITY
Common stockholders' equity	1,123	1,124.6
Retained earnings	2,718.3	2,544.6
Accumulated other comprehensive loss, net of tax	(26.3)	(32.1)	(25.7)	(27.9)
Total stockholders' equity	3,814.9	3,631.8
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	12,177.5	10,718.8
Treasury Stock, Carrying Basis	(0.1)	(5.3)
Accounts Receivable, Allowance for Credit Loss	2.4	2.6
OG&E [Member]
CURRENT ASSETS
Cash and cash equivalents	1.5	0	32	0
Accounts Receivable, after Allowance for Credit Loss, Current	242.3	156.3
Accrued unbilled revenues	82.5	67.7
Advances to parent	0	272
Fuel inventories	(35)	(36.5)
Materials and supplies, at average cost	111.4	116.2
Fuel clause under recoveries	98.2	0
Other	49.4	36.9
Total current assets	620.3	685.6
OTHER PROPERTY AND INVESTMENTS
Total other property and investments	3.9	4.1
PROPERTY, PLANT AND EQUIPMENT
In service	13,697.8	13,290.6
Construction work in progress	249.3	145.5
Total property, plant and equipment	13,947.1	13,436.1
Less: accumulated depreciation	4,257.3	4,067.6
Property, Plant and Equipment, Net	9,689.8	9,368.5
DEFERRED CHARGES AND OTHER ASSETS
Regulatory assets	1,264.9	415.6
Other	19	15.2
Total deferred charges and other assets	1,283.9	430.8
TOTAL ASSETS	11,597.9	10,489
CURRENT LIABILITIES
Accounts payable	230.7	236.7
Advances from parent	42.2	0
Customer deposits	80.6	81.1
Accrued taxes	76.1	53.3
Accrued interest	41.3	40.2
Accrued compensation	28.1	22.5
Fuel clause over recoveries	0	28.6
Other	40.4	33.5
Total current liabilities	539.4	495.9
LONG-TERM DEBT	3,995.9	3,494.4
DEFERRED CREDITS AND OTHER LIABILITIES
Accrued benefit obligations	93.5	135.4
Deferred income taxes	981.5	1,020.8
Deferred investment tax credits	11	10.9
Regulatory liabilities	1,247.7	1,188.9
Other	166.5	167.1
Total deferred credits and other liabilities	2,500.2	2,523.1
Total liabilities	7,035.5	6,513.4
STOCKHOLDERS' EQUITY
Common stockholders' equity	1,571.2	1,039.5
Retained earnings	2,991.2	2,936.1
Total stockholders' equity	4,562.4	3,975.6	$ 3,933.8	$ 3,958.3
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 11,597.9	$ 10,489

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) Parenthetical - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Accounts Receivable, Allowance for Credit Loss	$ 2.4	$ 2.6

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Millions	Total	OG&E [Member]	Common Stock	Common StockOG&E [Member]	Premium on Common Stock	Premium on Common StockOG&E [Member]	Retained Earnings	Retained EarningsOG&E [Member]	Accumulated Other Comprehensive Income (Loss)	Treasury Stock [Member]
Changes in Stockholders' Equity
Balance	$ 4,139.5		$ 2		$ 1,129.3		$ 3,036.1		$ (27.9)	$ 0
Common Stock, Shares, Outstanding			200,100,000	40,400,000
Treasury Stock, Common, Shares										0
Stockholders' Equity Attributable to Parent		$ 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
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(491.8)		$ 0		0		(491.8)		0	$ 0
Other Comprehensive Income (Loss), Net of Tax, Number of Shares			0							0
Dividends, Common Stock, Cash, Number of Shares			0							0
Other comprehensive loss, net of tax	(0.9)		$ 0		0		0		(0.9)	$ 0
Dividends, Common Stock, Cash	(79.3)		$ 0		0		(79.3)		0	$ 0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares			0	0						(200,000)
Stock-based compensation	(5.1)	0.9	$ 0	$ 0	(14.5)	0.9	0	0	0	$ 9.4
Treasury Stock, Shares, Acquired			0							200,000
Treasury Stock, Value, Acquired, Cost Method	(9.7)		$ 0		0		0		0	$ (9.7)
Net Income (Loss) Attributable to Parent		19.9		$ 0		0		19.9
Proceeds from Contributed Capital		0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(228.5)						(228.5)
Other comprehensive loss, net of tax	2.2	0
Net Income (Loss) Attributable to Parent	(228.5)	298.3
Balance	3,552.7		$ 2		1,114.8		2,465		(28.8)	$ (0.3)
Common Stock, Shares, Outstanding			200,100,000	40,400,000
Treasury Stock, Common, Shares										0
Stockholders' Equity Attributable to Parent		3,979.1		$ 100.9		936.6		2,941.6
Net Income (Loss), Including portion attributable to noncontrolling interest, Number of Shares			0	0						0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	85.9		$ 0		0		85.9		0	$ 0
Other Comprehensive Income (Loss), Net of Tax, Number of Shares			0							0
Dividends, Common Stock, Cash, Number of Shares			0	0						0
Other comprehensive loss, net of tax	0.9		$ 0		0		0		0.9	$ 0
Dividends, Common Stock, Cash	(77.6)		$ 0		0		(77.6)		0	$ 0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares			0	0						0
Stock-based compensation	2.3	0.7	$ 0	$ 0	2.3	0.7	0	0	0	$ 0
Net Income (Loss) Attributable to Parent		78.9		0		0		78.9
Dividends, Common Stock		(75)		$ 0		0		(75)
Balance	3,564.2		$ 2		1,117.1		2,473.3		(27.9)	$ (0.3)
Common Stock, Shares, Outstanding			200,100,000	40,400,000
Treasury Stock, Common, Shares										0
Stockholders' Equity Attributable to Parent		3,983.7		$ 100.9		937.3		2,945.5
Net Income (Loss), Including portion attributable to noncontrolling interest, Number of Shares			0	0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	177.4		$ 0		0		177.4		0
Other Comprehensive Income (Loss), Net of Tax, Number of Shares			0
Dividends, Common Stock, Cash, Number of Shares			0	0
Other comprehensive loss, net of tax	2.2	0	$ 0		0		0		2.2
Dividends, Common Stock, Cash	(80.5)		$ 0		0		(80.5)		0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares			0	0
Stock-based compensation	2.4	0.6	$ 0	$ 0	2.4	0.6	0	0	0
Treasury Stock, Shares, Acquired			0							100,000
Treasury Stock, Value, Acquired, Cost Method	(5)		$ 0		0		0		0	$ (5)
Net Income (Loss) Attributable to Parent	177.4	199.5		0		0		199.5
Dividends, Common Stock		(250)		$ 0		0		(250)
Balance	3,660.7		$ 2		1,119.5		2,570.2		(25.7)	$ (5.3)
Common Stock, Shares, Outstanding			200,100,000	40,400,000
Treasury Stock, Common, Shares										100,000
Stockholders' Equity Attributable to Parent		3,933.8		$ 100.9		937.9		2,895
Balance	3,631.8		$ 2		1,122.6		2,544.6		(32.1)	$ (5.3)
Common Stock, Shares, Outstanding			200,100,000	40,400,000
Treasury Stock, Common, Shares										100,000
Stockholders' Equity Attributable to Parent	3,631.8	3,975.6		$ 100.9		938.6		2,936.1
Net Income (Loss), Including portion attributable to noncontrolling interest, Number of Shares			0	0						0
Proceeds From Contributed Capital, Shares				0
Proceeds from Contributed Capital	530	530		$ 0				0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	52.7		$ 0		0		52.7		0	$ 0
Other Comprehensive Income (Loss), Net of Tax, Number of Shares			0							0
Dividends, Common Stock, Cash, Number of Shares			0							0
Other comprehensive loss, net of tax	3.5		$ 0		0		0		3.5	$ 0
Dividends, Common Stock, Cash	(81.7)		$ 0		0		(81.7)		0	$ 0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares			0	0						(100,000)
Stock-based compensation	(0.8)	0.5	$ 0	$ 0	(6)	0.5	0	0	0	$ 5.2
Net Income (Loss) Attributable to Parent		11.2		$ 0		0		11.2
Proceeds from Contributed Capital		530
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	418.1						418.1
Other comprehensive loss, net of tax	$ 5.8	0
Treasury Stock, Shares, Acquired	154,523
Net Income (Loss) Attributable to Parent	$ 418.1	320.1
Balance	3,605.5		$ 2		1,116.6		2,515.6		(28.6)	$ (0.1)
Common Stock, Shares, Outstanding			200,100,000	40,400,000
Treasury Stock, Common, Shares										0
Stockholders' Equity Attributable to Parent		4,517.3		$ 100.9		1,469.1		2,947.3
Net Income (Loss), Including portion attributable to noncontrolling interest, Number of Shares			0	0						0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	112.9		$ 0		0		112.9		0	$ 0
Other Comprehensive Income (Loss), Net of Tax, Number of Shares			0							0
Dividends, Common Stock, Cash, Number of Shares			0	0						0
Other comprehensive loss, net of tax	0.7		$ 0		0		0		0.7	$ 0
Dividends, Common Stock, Cash	(80.6)		$ 0		0		(80.6)		0	$ 0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares			0	0						0
Stock-based compensation	2.3	0.6	$ 0	$ 0	2.3	0.6	0	0	0	$ 0
Net Income (Loss) Attributable to Parent		85.1		0		0		85.1
Dividends, Common Stock		(45)		$ 0		0		(45)
Balance	3,640.8		$ 2		1,118.9		2,547.9		(27.9)	$ (0.1)
Common Stock, Shares, Outstanding			200,100,000	40,400,000
Treasury Stock, Common, Shares										0
Stockholders' Equity Attributable to Parent		4,558		$ 100.9		1,469.7		2,987.4
Net Income (Loss), Including portion attributable to noncontrolling interest, Number of Shares			0	0						0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	252.5		$ 0		0		252.5		0	$ 0
Other Comprehensive Income (Loss), Net of Tax, Number of Shares			0							0
Dividends, Common Stock, Cash, Number of Shares			0	0						0
Other comprehensive loss, net of tax	1.6	0	$ 0		0		0		1.6	$ 0
Dividends, Common Stock, Cash	(82.1)		$ 0		0		(82.1)		0	$ 0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Number of Shares			0	0						0
Stock-based compensation	2.1	0.6	$ 0	$ 0	2.1	0.6	0	0	0	$ 0
Net Income (Loss) Attributable to Parent	252.5	223.8		0		0		223.8
Dividends, Common Stock		(220)		$ 0		0		(220)
Balance	3,814.9		$ 2		$ 1,121		$ 2,718.3		$ (26.3)	$ (0.1)
Common Stock, Shares, Outstanding			200,100,000	40,400,000
Treasury Stock, Common, Shares										0
Stockholders' Equity Attributable to Parent	$ 3,814.9	$ 4,562.4		$ 100.9		$ 1,470.3		$ 2,991.2

CONDENSED CONSOLIDATED STATEM_6

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) Parenthetical - $ / shares	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2020
Statement of Stockholders' Equity [Abstract]
Common Stock, Dividends, Per Share, Declared	$ 0.4025	$ 0.4025	$ 0.3875	$ 0.3875

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Significant Accounting Policies [Text Block]	Summary of Significant Accounting Policies 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. September 30, December 31, (In millions) 2021 2020 REGULATORY ASSETS Current: Fuel clause under recoveries $ 98.2 $ — SPP cost tracker under recoveries (A) 7.7 7.0 Generation Capacity Replacement rider under recoveries (A) 1.7 4.4 Other (A) 7.7 8.4 Total current regulatory assets $ 115.3 $ 19.8 Non-current: Oklahoma Winter Storm Uri costs $ 756.3 $ — Oklahoma deferred storm expenses 173.8 158.8 Benefit obligations regulatory asset 130.6 164.9 Arkansas Winter Storm Uri costs 91.0 — Pension tracker 41.6 18.1 Sooner Dry Scrubbers 19.1 19.7 Arkansas deferred pension expenses 11.8 9.3 Unamortized loss on reacquired debt 9.1 9.7 COVID-19 impacts 8.0 6.4 Frontier Plant deferred expenses 7.1 6.4 Smart Grid 5.9 11.2 Other 10.6 11.1 Total non-current regulatory assets $ 1,264.9 $ 415.6 REGULATORY LIABILITIES Current: Oklahoma energy efficiency rider over recoveries (B) $ 4.7 $ 1.5 Fuel clause over recoveries — 28.6 Other (B) 1.6 5.0 Total current regulatory liabilities $ 6.3 $ 35.1 Non-current: Income taxes refundable to customers, net $ 938.8 $ 867.4 Accrued removal obligations, net 305.1 316.8 Other 3.8 4.7 Total non-current regulatory liabilities $ 1,247.7 $ 1,188.9 (A) Included in Other Current Assets in the balance sheets. (B) Included in Other Current Liabilities in the balance sheets. In February 2021, Winter Storm Uri resulted in record winter peak demand for electricity and extremely high natural gas and purchased power prices in OG&E's service territory. OG&E's natural gas costs for the month of February 2021 exceeded the total cost for all of 2020. The OCC allowed OG&E to create a regulatory asset for the Oklahoma portion of all deferred costs with an initial carrying charge based on the effective cost of the related debt financing for an amortization period to be determined at a later date. The APSC allowed OG&E to create a regulatory asset for the Arkansas portion of all deferred costs with an initial carrying charge equal to the current customer deposit interest rate to be recovered over a period of 10 years beginning in May 2021. For additional information, see Note 15. The Oklahoma deferred storm expenses regulatory asset is recovered through the Storm Cost Recovery Rider. Operation and maintenance expenses resulting from storm damage exceeding the amounts included in OG&E's base rates are deferred and typically amortized over a five-year period. To mitigate customer impact, OG&E has agreed to recover the portion related to 2020 excess storm costs through the Storm Cost Recovery Rider over a ten-year period.
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	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 condensed 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. Formed in 2013, 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
Basis of Accounting [Text Block]	Basis of Presentation The condensed financial statements included herein have been prepared by the Registrants, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations; however, the Registrants believe that the disclosures are adequate to prevent the information presented from being misleading. In the opinion of management, all adjustments necessary to fairly present the financial position of the Registrants at September 30, 2021 and December 31, 2020, the results of the Registrants' operations for the three and nine months ended September 30, 2021 and 2020 and the Registrants' cash flows for the nine months ended September 30, 2021 and 2020 have been included and are of a normal, recurring nature except as otherwise disclosed. Management also has evaluated the impact of events occurring after September 30, 2021 up to the date of issuance of these condensed financial statements, and these statements contain all necessary adjustments and disclosures resulting from that evaluation. Due to seasonal fluctuations and other factors, the Registrants' operating results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results that may be expected for the year ending December 31, 2021 or for any future period. The condensed financial statements and notes thereto should be read in conjunction with the audited financial statements and notes thereto included in the Registrants' 2020 Form 10-K .
Schedule of Regulatory Assets and Liabilities	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.
Comprehensive Income (Loss) Note [Text Block]	Accumulated Other Comprehensive Income (Loss) The following tables present changes in the components of accumulated other comprehensive income (loss) attributable to OGE Energy during the nine months ended September 30, 2021 and 2020. All amounts below are presented net of tax. (In millions) Pension Plan and Restoration of Retirement Income Plan Postretirement Benefit Plans Other Comprehensive Gain (Loss) from Unconsolidated Affiliates Total Balance at December 31, 2020 $ (34.1) $ 3.3 $ (1.3) $ (32.1) Other comprehensive income before reclassifications — — 0.6 0.6 Amounts reclassified from accumulated other comprehensive income (loss) 1.3 (0.9) — 0.4 Settlement cost 4.8 — — 4.8 Balance at September 30, 2021 $ (28.0) $ 2.4 $ (0.7) $ (26.3) (In millions) Pension Plan and Restoration of Retirement Income Plan Postretirement Benefit Plans Other Comprehensive Loss from Unconsolidated Affiliates Total Balance at December 31, 2019 $ (35.1) $ 7.8 $ (0.6) $ (27.9) Other comprehensive loss before reclassifications — — (0.9) (0.9) Amounts reclassified from accumulated other comprehensive income (loss) 2.9 (1.3) — 1.6 Settlement cost 1.5 — — 1.5 Balance at September 30, 2020 $ (30.7) $ 6.5 $ (1.5) $ (25.7) The following table presents significant amounts reclassified out of accumulated other comprehensive income (loss) attributable to OGE Energy by the respective line items in net income (loss) during the three and nine months ended September 30, 2021 and 2020. Details about Accumulated Other Comprehensive Income (Loss) Components Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in Three Months Ended Nine Months Ended September 30, September 30, (In millions) 2021 2020 2021 2020 Amortization of Pension Plan Actuarial losses $ (0.6) $ (1.2) $ (1.8) $ (3.8) (A) Prior service cost (0.1) — (0.1) — (A) Settlement cost (1.4) (1.8) (6.7) (2.1) (A) (2.1) (3.0) (8.6) (5.9) Income (Loss) Before Taxes (0.5) (0.8) (2.5) (1.5) Income Tax Expense (Benefit) $ (1.6) $ (2.2) $ (6.1) $ (4.4) Net Income (Loss) Amortization of postretirement benefit plans items: Prior service credit $ 0.4 $ 0.6 $ 1.3 $ 1.7 (A) Actuarial gains (losses) — — (0.1) 0.1 (A) 0.4 0.6 1.2 1.8 Income (Loss) Before Taxes 0.1 0.2 0.3 0.5 Income Tax Expense (Benefit) $ 0.3 $ 0.4 $ 0.9 $ 1.3 Net Income (Loss) Total reclassifications for the period, net of tax $ (1.3) $ (1.8) $ (5.2) $ (3.1) Net Income (Loss) (A) These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost (see Note 12 for additional information).
Allowance for Credit Losses	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 condensed balance sheets and is included in Other Operation and Maintenance Expense in the condensed statements of income. 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.

Accounting Pronouncements

Accounting Pronouncements	9 Months Ended
	Sep. 30, 2021
Accounting Standards Update and Change in Accounting Principle [Abstract]
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	Accounting PronouncementsThe Registrants believe that 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.

Revenue from Contracts with Cus

Revenue from Contracts with Customers (Notes)	9 Months Ended
	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
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 2. Management's Discussion and Analysis of Financial Condition and Results of Operations." Three Months Ended September 30, Nine Months Ended September 30, (In millions) 2021 2020 2021 2020 Residential $ 365.5 $ 294.9 $ 1,112.2 $ 664.6 Commercial 203.4 156.7 619.2 361.0 Industrial 79.9 59.3 264.1 145.5 Oilfield 68.0 50.6 257.5 127.2 Public authorities and street light 75.0 57.8 235.1 133.1 System sales revenues 791.8 619.3 2,488.1 1,431.4 Provision for rate refund — 4.8 — 3.2 Integrated market 17.2 18.0 447.6 33.7 Transmission 30.8 35.0 103.8 109.0 Other 8.4 10.7 (5.8) 22.9 Revenues from contracts with customers (A) $ 848.2 $ 687.8 $ 3,033.7 $ 1,600.2 (A) In February 2021, Winter Storm Uri resulted in record winter peak demand for electricity and extremely high natural gas and purchased power prices in OG&E's service territory. Operating revenues for the nine months ended September 30, 2021 significantly increased due to increased fuel, purchased power and direct transmission expenses, which are generally recoverable from customers, as a result of Winter Storm Uri. For further discussion, see Note 15 and "Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operation."

Investment in Unconsolidated Af

Investment in Unconsolidated Affiliates	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Equity Method Investments and Joint Ventures Disclosure [Text Block]	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 September 30, 2021 as presented in Note 13. 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 condensed 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 condensed statements of cash flows. At September 30, 2021, OGE Energy owned 111.0 million common units, or 25.5 percent, of Enable's outstanding common units. On September 30, 2021, Enable's common unit price closed at $8.12. OGE Energy recorded equity in earnings of unconsolidated affiliates of $41.2 million and $127.9 million for the three and nine months ended September 30, 2021, respectively, compared to equity in earnings of unconsolidated affiliates of $15.8 million for the three months ended September 30, 2020 and equity in losses of unconsolidated affiliates of $703.8 million for the nine months ended September 30, 2020. 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. These amortizations may also include gain or loss on dilution, net of proportional basis difference recognition. For more information concerning the formation of Enable and OGE Energy's accounting for its investment in Enable, see Note 5 within "Item 8. Financial Statements and Supplementary Data" in OGE Energy's 2020 Form 10-K . The following tables present summarized unaudited financial information for 100 percent of Enable as of September 30, 2021 and December 31, 2020 and for the three and nine months ended September 30, 2021 and 2020. September 30, December 31, Balance Sheet 2021 2020 (In millions) Current assets $ 536 $ 381 Non-current assets $ 11,244 $ 11,348 Current liabilities $ 1,299 $ 582 Non-current liabilities $ 3,248 $ 4,052 Three Months Ended Nine Months Ended September 30, September 30, Income Statement 2021 2020 2021 2020 (In millions) Total revenues $ 956 $ 596 $ 2,713 $ 1,759 Cost of natural gas and NGLs (excluding depreciation and amortization) $ 565 $ 250 $ 1,510 $ 653 Operating income $ 152 $ 100 $ 482 $ 326 Net income (loss) $ 107 $ (173) $ 341 $ (35) The following table presents a reconciliation of OGE Energy's equity in earnings (losses) of unconsolidated affiliates for the three and nine months ended September 30, 2021 and 2020. For further discussion of Enable's net income (loss), see "Item 2. Management's Discussion and Analysis - Results of Operations - OGE Holdings (Natural Gas Midstream Operations)." Three Months Ended Nine Months Ended September 30, September 30, (In millions) 2021 2020 2021 2020 Enable net income (loss) $ 107.0 $ (173.0) $ 341.0 $ (35.0) OGE Energy's percent ownership at period end 25.5 % 25.5 % 25.5 % 25.5 % OGE Energy's portion of Enable net income (loss) $ 27.5 $ (44.0) $ 87.0 $ (8.9) Amortization of basis difference and dilution recognition (A) 13.7 59.8 40.9 85.1 Impairment of OGE Energy's equity method investment in Enable (B) — — — (780.0) Equity in earnings (losses) of unconsolidated affiliates (C) $ 41.2 $ 15.8 $ 127.9 $ (703.8) (A) Includes loss on dilution, net of proportional basis difference recognition. (B) 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 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 2020. Further discussion can be found in OGE Energy's 2020 Form 10-K . (C) For the three and nine months ended September 30, 2020, Enable recorded a $225.0 million impairment on its SESH equity method investment, which is included in their net loss for each period. 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 (loss) 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, 2020 to September 30, 2021. The basis difference is amortized over approximately 30 years. (In millions) Basis difference at December 31, 2020 $ 1,332.3 Amortization of basis difference (A) (42.1) Basis difference at September 30, 2021 $ 1,290.2 (A) Includes proportional basis difference recognition due to dilution. Distributions received from Enable were $18.3 million during both the three months ended September 30, 2021 and 2020 and $55.0 million and $73.3 million during the nine months ended September 30, 2021 and 2020, respectively. On October 26, 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. Enable Merger Agreement with Energy Transfer 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. Energy Transfer is a publicly traded limited partnership with core operations that include complementary natural gas midstream, intrastate and interstate transportation and storage assets; crude oil, NGLs and refined product transportation and terminalling assets; NGL fractionation; and various acquisition and marketing assets. 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 subject to the receipt of the required approvals from the holders of a majority of Enable's common units. Contemporaneously with the execution of the merger agreement, OGE Energy entered into a support agreement with Enable and Energy Transfer in which OGE Energy agreed to vote its common units in favor of the merger. In April 2021, CenterPoint and OGE Energy, who collectively own approximately 79.2 percent of Enable's common units, delivered written consents approving the merger agreement, and those consents are sufficient to approve the merger. The transaction also is subject to the receipt of anti-trust approvals and other customary closing conditions. The transaction is anticipated to close in 2021. 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. 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. Assuming the successful completion of the merger, OGE Energy intends to exit the midstream segment in a prudent manner.

Related Party Disclosures

Related Party Disclosures	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
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 $32.2 million and $32.7 million during the three months ended September 30, 2021 and 2020, respectively, and $101.3 million and $107.5 million during the nine months ended September 30, 2021 and 2020, respectively. 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 $0.1 million during both the three months ended September 30, 2021 and 2020 and $0.3 million during both the nine months ended September 30, 2021 and 2020. Pursuant to a seconding agreement, OGE Energy provides seconded employees to Enable to support Enable's operations. As of September 30, 2021, 64 employees that participate in OGE Energy's defined benefit and retirement plans are seconded to Enable. OGE Energy billed Enable for reimbursement of $2.5 million and $3.5 million during the three months ended September 30, 2021 and 2020, respectively, and $10.3 million and $13.6 million during the nine months ended September 30, 2021 and 2020, 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 $17.6 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 $1.1 million as of September 30, 2021 and $2.0 million as of December 31, 2020, which are included in Accounts Receivable in OGE Energy's condensed 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 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 compensates Enable when Enable's deliveries exceed OG&E's pipeline nominations. Enable compensates OG&E when OG&E's pipeline nominations exceed Enable's deliveries. The following table presents summarized related party transactions between OG&E and Enable during the three and nine months ended September 30, 2021 and 2020. Three Months Ended Nine Months Ended September 30, September 30, (In millions) 2021 2020 2021 2020 Operating revenues: Electricity to power electric compression assets $ 4.1 $ 4.5 $ 10.0 $ 11.7 Fuel, purchased power and direct transmission expense: Natural gas transportation services $ 9.4 $ 9.3 $ 23.4 $ 23.4 Natural gas purchases (sales) $ (7.7) $ 3.2 $ (28.3) $ 2.2

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	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 September 30, 2021 and December 31, 2020. The following table presents the carrying amount and fair value of the Registrants' financial instruments at September 30, 2021 and December 31, 2020, as well as the classification level within the fair value hierarchy. September 30, December 31, 2021 2020 (In millions) Carrying Amount Fair Carrying Amount Fair Classification Long-term Debt (including Long-term Debt due within one year): OGE Energy Senior Notes $ 499.9 $ 500.1 $ — $ — Level 2 OG&E Senior Notes $ 3,851.1 $ 4,503.4 $ 3,349.6 $ 4,182.1 Level 2 OG&E Industrial Authority Bonds $ 135.4 $ 135.4 $ 135.4 $ 135.4 Level 2 OG&E Tinker Debt $ 9.4 $ 10.0 $ 9.4 $ 10.7 Level 3

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Share-based Payment Arrangement [Text Block]	Stock-Based Compensation The following table presents the Registrants' pre-tax compensation expense and related income tax benefit for the three and nine months ended September 30, 2021 and 2020 related to performance units and restricted stock units for the Registrants' employees. OGE Energy OG&E Three Months Ended September 30, Nine Months Ended September 30, Three Months Ended September 30, Nine Months Ended September 30, (In millions) 2021 2020 2021 2020 2021 2020 2021 2020 Performance units: Total shareholder return $ 1.9 $ 1.9 $ 5.8 $ 5.6 $ 0.5 $ 0.5 $ 1.4 $ 1.8 Earnings per share — 0.2 — 0.5 — — — 0.1 Total performance units 1.9 2.1 5.8 6.1 0.5 0.5 1.4 1.9 Restricted stock units 0.4 0.3 1.3 0.6 0.1 0.1 0.2 0.3 Total compensation expense $ 2.3 $ 2.4 $ 7.1 $ 6.7 $ 0.6 $ 0.6 $ 1.6 $ 2.2 Income tax benefit $ 0.6 $ 0.6 $ 1.8 $ 1.7 $ 0.1 $ 0.2 $ 0.4 $ 0.6

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	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 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. Oklahoma Corporate Tax Rate Change In May 2021, Oklahoma enacted a reduction of the corporate income tax rate to four percent from the previous six percent. This rate reduction will take effect January 1, 2022. ASC 740, "Income Taxes," requires deferred tax assets and liabilities to be measured at the enacted tax rate expected to apply when temporary differences are to be realized or settled. Therefore, during the second quarter of 2021, the Registrants revalued state deferred tax liabilities to reflect this change in tax rate. For entities subject to ASC 980, "Accounting for Regulated Entities," such as OG&E, those entities are required to recognize a regulatory liability for the decrease in taxes payable for the change in tax rates that are expected to be returned to customers through future rates and to recognize a regulatory asset for the increase in taxes receivable for the change in tax rates that are expected to be recovered from customers through future rates. The revaluation resulted in a regulatory liability of $97.7

Common Equity

Common Equity	9 Months Ended
	Sep. 30, 2021
Common Equity [Text Block]	Common Equity Automatic Dividend Reinvestment and Stock Purchase Plan OGE Energy issued no shares of common stock under its Automatic Dividend Reinvestment and Stock Purchase Plan during the three and nine months ended September 30, 2021. 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. Three Months Ended September 30, Nine Months Ended September 30, (In millions except per share data) 2021 2020 2021 2020 Net income (loss) $ 252.5 $ 177.4 $ 418.1 $ (228.5) Average common shares outstanding: Basic average common shares outstanding 200.2 200.1 200.1 200.1 Effect of dilutive securities: Contingently issuable shares (performance and restricted stock units) 0.2 0.3 0.2 — Diluted average common shares outstanding 200.4 200.4 200.3 200.1 Basic earnings (loss) per average common share $ 1.26 $ 0.89 $ 2.09 $ (1.14) Diluted earnings (loss) per average common share $ 1.26 $ 0.89 $ 2.09 $ (1.14) Anti-dilutive shares excluded from earnings per share calculation — — — 0.3

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2021
Long-term Debt, Unclassified [Abstract]
Long-Term Debt	Long-Term Debt At September 30, 2021, the Registrants were in compliance with all of their debt agreements. 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) 0.11% - 0.27% Garfield Industrial Authority, January 1, 2025 $ 47.0 0.11% - 0.33% Muskogee Industrial Authority, January 1, 2025 32.4 0.11% - 0.27% 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 condensed balance sheets. OG&E believes that it has sufficient liquidity to meet these obligations. Issuance of Long-Term Debt

Short-Term Debt and Credit Faci

Short-Term Debt and Credit Facilities	9 Months Ended
	Sep. 30, 2021
Short-term Debt [Abstract]
Short-Term Debt and Credit Facilities	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. OGE Energy had $383.2 million and $95.0 million of short-term debt at September 30, 2021 and December 31, 2020, respectively. At September 30, 2021, OG&E had $42.2 million in advances from OGE Energy compared to $272.0 million in advances to OGE Energy at December 31, 2020. In March 2021, OGE Energy entered into a $1.0 billion unsecured 364-day term loan agreement and borrowed the full $1.0 billion to help cover the increased fuel and purchased power costs incurred by OG&E during Winter Storm Uri. The term loan contained substantially the same covenants as OGE Energy's $450.0 million revolving credit agreement, including various financial ratio covenants. Contemporaneously with the closing of the term loan agreement, in March 2021, OGE Energy made a capital contribution of $530.0 million to OG&E using the term loan proceeds, and OGE Energy also loaned $470.0 million to OG&E pursuant to an intercompany note issued by OG&E to OGE Energy. In May 2021, OG&E repaid the $470.0 million to OGE Energy, and OGE Energy used this repayment and other funds from its issuance of senior notes in May 2021 to repay $900.0 million of the $1.0 billion term loan, as further discussed in Note 10. At September 30, 2021, the weighted-average interest rate for the amount drawn on the term loan was 0.832 percent. The following table presents information regarding the Registrants' revolving credit agreements at September 30, 2021. Aggregate Amount Weighted-Average Entity Commitment Outstanding (A) Interest Rate Expiration (In millions) OGE Energy (B) $ 450.0 $ 283.2 0.18 % (E) March 8, 2024 (F) OG&E (C)(D) 450.0 0.4 1.15 % (E) March 8, 2024 (F) Total $ 900.0 $ 283.6 0.18 % (A) Includes direct borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit at September 30, 2021. (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) 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 September 30, 2021, there were no intercompany borrowings under this agreement. (E) Represents the weighted-average interest rate for the outstanding borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit. (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. 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.

Retirement Plans and Postretire

Retirement Plans and Postretirement Benefit Plans	9 Months Ended
	Sep. 30, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Pension and Other Postretirement Benefits Disclosure [Text Block]	Retirement Plans and Postretirement Benefit Plans 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 the nine months ended September 30, 2021, 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 below. The pension settlement charges did not require a cash outlay by the Registrants and did not increase total pension expense over time, as the charge was an acceleration of costs that otherwise would be recognized as pension expense in future periods. 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 condensed financial statements. Service cost is presented within Other Operation and Maintenance Expense, and the remaining net periodic benefit cost components as listed in the following tables are presented within Other Net Periodic Benefit 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 Expense in the statements of income. Pension Plan Restoration of Retirement Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended OGE Energy September 30, September 30, September 30, September 30, (In millions) 2021 2020 2021 2020 2021 2020 2021 2020 Service cost $ 2.8 $ 3.3 $ 8.4 $ 9.8 $ 0.3 $ 0.2 $ 0.6 $ 0.6 Interest cost 3.1 4.2 10.0 13.4 — 0.1 0.1 0.2 Expected return on plan assets (8.5) (9.4) (25.6) (28.0) — — — — Amortization of net loss 2.3 4.3 7.0 12.7 — 0.1 0.1 0.4 Amortization of unrecognized prior service cost (A) — — — — 0.1 — 0.1 — Settlement cost 3.7 12.1 35.4 12.1 1.7 0.4 2.1 0.7 Total net periodic benefit cost 3.4 14.5 35.2 20.0 2.1 0.8 3.0 1.9 Less: Amount paid by unconsolidated affiliates (B) (0.1) 0.5 (0.2) 1.6 — 0.1 — 0.1 Net periodic benefit cost $ 3.5 $ 14.0 $ 35.4 $ 18.4 $ 2.1 $ 0.7 $ 3.0 $ 1.8 Pension Plan Restoration of Retirement Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended OG&E September 30, September 30, September 30, September 30, (In millions) 2021 2020 2021 2020 2021 2020 2021 2020 Service cost $ 2.0 $ 2.3 $ 5.8 $ 6.8 $ — $ — $ — $ 0.1 Interest cost 2.3 3.2 7.3 10.0 — — — 0.1 Expected return on plan assets (6.2) (7.0) (18.5) (20.9) — — — — Amortization of net loss 1.7 3.0 5.2 9.0 — 0.1 0.1 0.3 Settlement cost 2.6 10.3 29.2 10.3 1.3 0.5 1.6 0.5 Total net periodic benefit cost 2.4 11.8 29.0 15.2 1.3 0.6 1.7 1.0 Plus: Amount allocated from OGE Energy (B) 0.7 1.5 5.3 2.5 0.8 0.2 1.3 0.8 Net periodic benefit cost $ 3.1 $ 13.3 $ 34.3 $ 17.7 $ 2.1 $ 0.8 $ 3.0 $ 1.8 (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 tables above, for the Pension and Restoration of Retirement Income Plans for the three and nine months ended September 30, 2021 and 2020, the Registrants recognized the following: Three Months Ended September 30, Nine Months Ended September 30, (In millions) 2021 2020 2021 2020 Increase of pension expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A) $ 3.9 $ 2.4 $ 11.1 $ 5.7 Deferral of pension expense related to pension settlement charges: Oklahoma jurisdiction (A) $ 4.4 $ 10.8 $ 33.3 $ 11.1 Arkansas jurisdiction (A) $ 0.4 $ 1.0 $ 3.1 $ 1.0 (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 Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, (In millions) 2021 2020 2021 2020 2021 2020 2021 2020 Service cost $ 0.1 $ 0.1 $ 0.2 $ 0.2 $ — $ — $ 0.1 $ 0.1 Interest cost 0.9 1.0 2.6 3.1 0.6 0.8 1.9 2.4 Expected return on plan assets (0.4) (0.5) (1.4) (1.4) (0.4) (0.4) (1.3) (1.2) Amortization of net loss 0.7 0.5 2.1 1.5 0.6 0.5 2.0 1.6 Amortization of unrecognized prior service cost (A) (1.8) (2.1) (5.2) (6.3) (1.2) (1.5) (3.7) (4.6) Total net periodic benefit cost (0.5) (1.0) (1.7) (2.9) (0.4) (0.6) (1.0) (1.7) Less: Amount paid by unconsolidated affiliates (B) (0.1) (0.2) (0.4) (0.6) Plus: Amount allocated from OGE Energy (B) (0.1) (0.2) (0.3) (0.6) Net periodic benefit cost $ (0.4) $ (0.8) $ (1.3) $ (2.3) $ (0.5) $ (0.8) $ (1.3) $ (2.3) (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 for the three and nine months ended September 30, 2021 and 2020, the Registrants recognized the following: Three Months Ended September 30, Nine Months Ended September 30, (In millions) 2021 2020 2021 2020 Increase of postretirement expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A) $ 0.1 $ 0.4 $ 0.3 $ 1.2 (A) Included in the Pension tracker, as presented in the regulatory assets and liabilities table in Note 1. OGE Energy OG&E Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, (In millions) 2021 2020 2021 2020 2021 2020 2021 2020 Capitalized portion of net periodic pension benefit cost $ 0.9 $ 0.9 $ 2.5 $ 2.7 $ 0.7 $ 0.8 $ 2.1 $ 2.3 Capitalized portion of net periodic postretirement benefit cost $ 0.1 $ — $ 0.2 $ 0.1 $ — $ — $ 0.1 $ 0.1 Pension Plan Funding In January 2021, OGE Energy made a $40.0 million contribution to its Pension Plan, of which $30.0 million was attributed to OG&E. No additional contributions are expected in 2021.

Report of Business Segments

Report of Business Segments	9 Months Ended
	Sep. 30, 2021
Segment Reporting [Abstract]
Report of Business Segments	Report of Business SegmentsOGE 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) the 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 three and nine months ended September 30, 2021 and 2020. Three Months Ended September 30, 2021 Electric Utility Natural Gas Midstream Operations Other Eliminations Total (In millions) Operating revenues $ 864.4 $ — $ — $ — $ 864.4 Fuel, purchased power and direct transmission expense 330.1 — — — 330.1 Other operation and maintenance 115.8 0.3 (0.7) — 115.4 Depreciation and amortization 108.6 — — — 108.6 Taxes other than income 24.6 0.1 0.8 — 25.5 Operating income (loss) 285.3 (0.4) (0.1) — 284.8 Equity in earnings of unconsolidated affiliates — 41.2 — — 41.2 Other income (expense) 2.9 (0.5) (0.2) (0.1) 2.1 Interest expense 38.0 — 1.6 (0.1) 39.5 Income tax expense 26.4 9.5 0.2 — 36.1 Net income (loss) $ 223.8 $ 30.8 $ (2.1) $ — $ 252.5 Investment in unconsolidated affiliates $ — $ 449.5 $ 29.4 $ — $ 478.9 Total assets $ 11,597.9 $ 451.8 $ 293.3 $ (165.5) $ 12,177.5 Three Months Ended September 30, 2020 Electric Utility Natural Gas Midstream Operations Other Eliminations Total (In millions) Operating revenues $ 702.1 $ — $ — $ — $ 702.1 Fuel, purchased power and direct transmission expense 209.1 — — — 209.1 Other operation and maintenance 110.1 0.3 (0.7) — 109.7 Depreciation and amortization 100.5 — — — 100.5 Taxes other than income 23.9 0.2 0.7 — 24.8 Operating income (loss) 258.5 (0.5) — — 258.0 Equity in earnings of unconsolidated affiliates — 15.8 — — 15.8 Other income (expense) 0.6 (0.7) (0.5) (0.2) (0.8) Interest expense 39.5 — 0.5 (0.2) 39.8 Income tax expense 20.1 4.5 31.2 — 55.8 Net income (loss) $ 199.5 $ 10.1 $ (32.2) $ — $ 177.4 Investment in unconsolidated affiliates $ — $ 355.8 $ 21.0 $ — $ 376.8 Total assets $ 10,323.3 $ 358.7 $ 109.6 $ (294.0) $ 10,497.6 Nine Months Ended September 30, 2021 Electric Utility Natural Gas Midstream Operations Other Eliminations Total (In millions) Operating revenues $ 3,072.4 $ — $ — $ — $ 3,072.4 Fuel, purchased power and direct transmission expense 1,876.9 — — — 1,876.9 Other operation and maintenance 344.4 2.3 (2.8) — 343.9 Depreciation and amortization 310.2 — — — 310.2 Taxes other than income 75.3 0.3 2.9 — 78.5 Operating income (loss) 465.6 (2.6) (0.1) — 462.9 Equity in earnings of unconsolidated affiliates — 127.9 — — 127.9 Other income (expense) 5.8 (1.2) (0.8) (0.9) 2.9 Interest expense 114.3 — 5.4 (0.9) 118.8 Income tax expense (benefit) 37.0 23.2 (3.4) — 56.8 Net income (loss) $ 320.1 $ 100.9 $ (2.9) $ — $ 418.1 Investment in unconsolidated affiliates $ — $ 449.5 $ 29.4 $ — $ 478.9 Total assets $ 11,597.9 $ 451.8 $ 293.3 $ (165.5) $ 12,177.5 Nine Months Ended September 30, 2020 Electric Utility Natural Gas Midstream Operations Other Eliminations Total (In millions) Operating revenues $ 1,636.9 $ — $ — $ — $ 1,636.9 Fuel, purchased power and direct transmission expense 481.5 — — — 481.5 Other operation and maintenance 348.8 1.2 (2.8) — 347.2 Depreciation and amortization 292.2 — — — 292.2 Taxes other than income 72.8 0.4 3.1 — 76.3 Operating income (loss) 441.6 (1.6) (0.3) — 439.7 Equity in losses of unconsolidated affiliates (A) — (703.8) — — (703.8) Other income (expense) 2.9 (0.7) 2.5 (1.4) 3.3 Interest expense 115.7 — 4.6 (1.4) 118.9 Income tax expense (benefit) 30.5 (167.2) (14.5) — (151.2) Net income (loss) $ 298.3 $ (538.9) $ 12.1 $ — $ (228.5) Investment in unconsolidated affiliates $ — $ 355.8 $ 21.0 $ — $ 376.8 Total assets $ 10,323.3 $ 358.7 $ 109.6 $ (294.0) $ 10,497.6 (A) In 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Note 4.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2021
Long-term Purchase Commitment [Line Items]
Commitments and Contingencies Disclosure [Text Block]	Commitments and Contingencies Except as set forth below, in Note 15 and under "Environmental Laws and Regulations" in Item 2 of Part I and in Item 1 of Part II of this Form 10-Q, the circumstances set forth in Notes 15 and 16 to the financial statements included in the Registrants' 2020 Form 10-K appropriately represent, in all material respects, the current status of the Registrants' material commitments and contingent liabilities. 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. Other

Regulated Operations

Regulated Operations	9 Months Ended
	Sep. 30, 2021
Regulated Operations [Abstract]
Rate Matters and Regulation	Rate Matters and Regulation Except as set forth below, the circumstances set forth in Note 16 to the financial statements included in the Registrants' 2020 Form 10-K appropriately represent, in all material respects, the current status of the Registrants' regulatory matters. Completed Regulatory Matters APSC Proceedings Arkansas 2020 Formula Rate Plan Filing In October 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 agreed not to oppose the settlement. The settlement agreement included a revenue increase of $6.7 million, which is the maximum amount statutorily allowed in this filing. Additionally, the settling parties did 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. On March 9, 2021, the APSC issued a final order approving the non-unanimous settlement agreement, and new rates became effective April 1, 2021. Disconnection Procedures Related to COVID-19 In September 2020, the APSC invited 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 proposed to reinstate routine service disconnection activities and collection of past due amounts once the moratorium was lifted. OG&E submitted its proposed Transitional Plan in October 2020. On February 8, 2021, the APSC announced a target date of May 3, 2021 to lift the moratorium on disconnections and specified 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. On March 26, 2021, the APSC confirmed the lifting of the moratorium on disconnections on May 3, 2021 and directed utilities to take specific steps prior to resuming disconnections. OG&E resumed disconnections on May 3, 2021. Arkansas Approval to Construct Out of State Generation On March 3, 2021, OG&E filed an application with the APSC to request approval to construct a 5 MW solar facility in Oklahoma. The APSC issued an order on April 6, 2021, finding OG&E's application in the public interest, conditioned on Arkansas customers being held harmless and not subject to cost recovery associated with the project. OG&E expects the costs associated with constructing this solar facility to be fully recovered in Oklahoma. Integrated Resource Plan OG&E has conducted technical conferences for stakeholder engagement on its draft triennial system-wide IRP and, in October 2021, issued its final 2021 IRP to the APSC. This 2021 IRP identified system-wide capacity needs of 145, 183, 417 and 514 MWs in 2023, 2024, 2025 and 2026, respectively. OCC Proceedings Oklahoma Grid Enhancement Plan In November 2020, the OCC issued a final order approving a Joint Stipulation and Settlement Agreement that allows for interim recovery of OG&E's costs associated with its grid enhancement plan. The approved agreement 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. The rider mechanism became effective on February 1, 2021. OG&E reports to the OCC new projects completed each quarter, and the cost recovery factor is adjusted to include those projects after a stakeholder review. OG&E has submitted its report for projects that were placed in service through September 30, 2021. The cost recovery factors that include those projects will become effective on December 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. Integrated Resource Plan OG&E has conducted technical conferences for stakeholder engagement on its draft triennial system-wide IRP and, in October 2021, issued its final 2021 IRP to the OCC. This 2021 IRP identified system-wide capacity needs of 145, 183, 417 and 514 MWs in 2023, 2024, 2025 and 2026, respectively. 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 through 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. In February 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. In March 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 court issued a decision on August 27, 2021, denying review and holding that the SPP was prohibited by the filed rate doctrine from imposing Z2 charges during the 2008 through 2015 historical period. The court further held that the FERC reasonably exercised its remedial authority to order the SPP to refund the retroactive upgrade charge. The court did not direct a time frame or procedures for the SPP to implement refunds. OG&E and the SPP filed a petition for rehearing of the court's decision, which was denied on October 29, 2021. The court will return the matter to the FERC for action in accordance with its opinion on November 5, 2021. If the FERC proceeds to order refunds in full, 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. The SPP has stated in filings it made with the FERC while the appeal was pending that there are considerable complexities in implementing the refunds that will have to be resolved before they can be paid. Payment of refunds would shift recovery of these upgrade credits 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. As of September 30, 2021, the Registrants have reserved $13.0 million plus estimated interest for a potential refund. In January 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 in April 2020 without this limited recovery, and with the alternative rate mechanism, and the FERC approved it in June 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 subsequent to July 2020. 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. Incentive Adders for Transmission Rates The FERC issued a NOPR on March 20, 2020, and issued a supplemental NOPR on April 15, 2021, proposing to update its transmission incentives policy. Among other things, the NOPR proposes (i) the current 50-basis point return on equity adder for RTO/ISO participation would be applicable only to transmitting utilities that join an RTO/ISO, and this incentive would only apply for the first three years in which the utility is an RTO/ISO member and (ii) transmitting utilities that have been members of an RTO/ISO for three years or more, such as OG&E, would be required to make a compliance filing to remove the existing return on equity adder from their rates. OG&E is currently evaluating the potential impacts of this proposed rule. Currently, there is no specific deadline for the FERC to take further action, and it is unknown whether the FERC will address the RTO participation adder individually or as part of a larger order on transmission incentives. APSC Proceedings Winter Storm Uri In February 2021, Winter Storm Uri resulted in record winter peak demand for electricity and extremely high natural gas and purchased power prices in OG&E's service territory. On April 1, 2021, OG&E filed with the APSC a Motion for Authority to Establish Special Regulatory Treatment within the Energy Cost Recovery Rider to Defer Extraordinary Fuel Costs Incurred Due to Winter Storm Uri. More specifically, OG&E's motion sought approval to defer, amortize and recover the extraordinary fuel costs over a ten-year period with a carrying charge of OG&E's pre-tax rate of return of 6.60 percent, through a special factor within OG&E's Energy Cost Recovery Rider beginning with the first billing cycle of May 2021. On April 13, 2021, the APSC issued an order allowing OG&E interim recovery at an interest rate equal to the customer deposit interest rate, which is currently 0.8 percent, over a period of ten years beginning with the first billing cycle of May 2021. Recovery is subject to a true-up after the APSC determines the appropriate allocation, length of recovery and carrying charge. On May 4, 2021, OG&E filed testimony further supporting its 10-year amortization period and a carrying charge of OG&E's pre-tax rate of return of 6.60 percent. In April 2021, Arkansas enacted legislation to amend its storm recovery securitization statute to allow for both electric and gas utilities to recover through securitization extraordinary natural gas, fuel and purchased power costs caused by storms. The amended statute authorizes the APSC to issue a financing order for the issuance of securitization bonds upon a finding it is reasonably expected to lower overall costs or mitigate rate impacts as compared with traditional utility financing. Upon the initiation of a securitization application, the APSC has 135 days to issue an order. The requesting utility has two years from the date of the financing order to issue the securitization bonds. The amended statute allows carrying costs at a utility's weighted average cost of capital from the date of when the costs were incurred until the date when bonds are ultimately issued. On May 20, 2021, OG&E filed a motion for suspension of procedural schedule, which the APSC approved, to investigate and evaluate the potential securitization recovery of the Arkansas jurisdictional portion of the Winter Storm Uri costs. OG&E intends to apply for securitization in early 2022 if it is deemed to strike the right balance between protecting the credit strength of OG&E and providing customer savings. As of September 30, 2021, OG&E has deferred $91.0 million to a regulatory asset, as indicated in Note 1. Arkansas 2021 Formula Rate Plan Filing On October 1, 2021, OG&E filed its fourth evaluation report under its Formula Rate Plan, including a request to increase its Arkansas retail revenues by $6.4 million. OG&E also requested extending its Formula Rate Plan Rider by five years. If approved, new rates will be effective April 1, 2022. 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 $26.0 million to $35.4 million for all five cases, of which $2.5 million to $3.9 million would apply to the three cases where the OCC ruled in favor of the electric cooperatives. Winter Storm Uri In February 2021, Winter Storm Uri resulted in record winter peak demand for electricity and extremely high natural gas and purchased power prices in OG&E's service territory. 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 Winter Storm Uri. The steps included: (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. On March 18, 2021, the OCC approved OG&E's filing to establish a regulatory asset. The approval allowed OG&E to create a regulatory asset for all deferred costs with an initial carrying charge based on the effective cost of the debt financing, until such time where the prudency of this event is evaluated, the amortization period is decided on and a long-term carry cost is established. In April 2021, Oklahoma enacted legislation to allow for the securitization of costs incurred during Winter Storm Uri. The new statute authorizes the OCC to issue a financing order for the issuance of securitization bonds after consideration of certain factors, including but not limited to, mitigated impacts and savings for customers through the use of ratepayer-backed securitization bonds as compared to traditional utility financing. The OCC must issue a financing order within 180 days after receiving all necessary information required by the statute. Under the statute, the Oklahoma Development Finance Authority is responsible for issuing the securitization bonds within two years from the date of the financing order. Carrying costs will be included at a rate and time determined by the OCC and continue until the bonds are issued. On April 26, 2021, OG&E filed an application pursuant to the Act seeking OCC approval to securitize its costs related to Winter Storm Uri and to receive an interim carrying charge on OG&E's regulatory asset balance at its weighted-average cost of capital for the period between April 2022 and the date when the securitized bonds are issued. On June 18, 2021, OG&E filed its direct testimony which supports the prudence of the costs incurred during Winter Storm Uri and demonstrates the customer savings associated with securitization as opposed to traditional utility financing. On October 8, 2021, OG&E filed a settlement agreement between OG&E, the Public Utility Division Staff of the OCC, the Oklahoma Industrial Energy Consumers, the OG&E Shareholders Association and Walmart Inc. The settlement agreement is subject to approval by the OCC. The settling parties agreed the OCC should issue a financing order authorizing the securitization of $760.0 million, which includes estimated finance costs and is subject to change for carrying costs, any updates from the SPP settlement process and actual securitization issuance costs. The settling parties agree that OG&E's total extreme purchase costs (for natural gas and wholesale energy purchases) are currently estimated to be $748.9 million, of which it is agreed that $739.1 million should be deemed prudent. Any adjustments for this settlement will be recorded in the fourth quarter of 2021. The OCC conducted a hearing on the settlement agreement on October 13-14, 2021. The Administrative Law Judge is expected to draft a recommendation for deliberation on a final order by the OCC, and the final order is expected by December 15, 2021. 2020 Oklahoma Fuel Prudency

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Consolidation, Policy [Policy Text Block]	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 condensed 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.
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation The condensed financial statements included herein have been prepared by the Registrants, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations; however, the Registrants believe that the disclosures are adequate to prevent the information presented from being misleading. In the opinion of management, all adjustments necessary to fairly present the financial position of the Registrants at September 30, 2021 and December 31, 2020, the results of the Registrants' operations for the three and nine months ended September 30, 2021 and 2020 and the Registrants' cash flows for the nine months ended September 30, 2021 and 2020 have been included and are of a normal, recurring nature except as otherwise disclosed. Management also has evaluated the impact of events occurring after September 30, 2021 up to the date of issuance of these condensed financial statements, and these statements contain all necessary adjustments and disclosures resulting from that evaluation. Due to seasonal fluctuations and other factors, the Registrants' operating results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results that may be expected for the year ending December 31, 2021 or for any future period. The condensed financial statements and notes thereto should be read in conjunction with the audited financial statements and notes thereto included in the Registrants' 2020 Form 10-K .
Public Utilities, Policy [Policy 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.
Equity Method Investments [Policy Text Block]	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. Formed in 2013, 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. 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 September 30, 2021 as presented in Note 13. 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 condensed 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 condensed statements of cash flows.
Fair Value of Financial Instruments, Policy [Policy Text Block]	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).
Income Tax, Policy [Policy Text Block]	OGE Energy files consolidated income tax returns in the U.S. federal jurisdiction and various state jurisdictions.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.
Earnings Per Share, Policy [Policy Text Block]	Earnings (Loss) Per Share
Financing Receivable, Allowance for Credit Losses, Policy for Uncollectible Amounts	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 condensed balance sheets and is included in Other Operation and Maintenance Expense in the condensed statements of income. 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.

Fair Value Measures and Disclos

Fair Value Measures and Disclosures (Policies)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments, Policy [Policy Text Block]	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).

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2021
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. September 30, December 31, (In millions) 2021 2020 REGULATORY ASSETS Current: Fuel clause under recoveries $ 98.2 $ — SPP cost tracker under recoveries (A) 7.7 7.0 Generation Capacity Replacement rider under recoveries (A) 1.7 4.4 Other (A) 7.7 8.4 Total current regulatory assets $ 115.3 $ 19.8 Non-current: Oklahoma Winter Storm Uri costs $ 756.3 $ — Oklahoma deferred storm expenses 173.8 158.8 Benefit obligations regulatory asset 130.6 164.9 Arkansas Winter Storm Uri costs 91.0 — Pension tracker 41.6 18.1 Sooner Dry Scrubbers 19.1 19.7 Arkansas deferred pension expenses 11.8 9.3 Unamortized loss on reacquired debt 9.1 9.7 COVID-19 impacts 8.0 6.4 Frontier Plant deferred expenses 7.1 6.4 Smart Grid 5.9 11.2 Other 10.6 11.1 Total non-current regulatory assets $ 1,264.9 $ 415.6 REGULATORY LIABILITIES Current: Oklahoma energy efficiency rider over recoveries (B) $ 4.7 $ 1.5 Fuel clause over recoveries — 28.6 Other (B) 1.6 5.0 Total current regulatory liabilities $ 6.3 $ 35.1 Non-current: Income taxes refundable to customers, net $ 938.8 $ 867.4 Accrued removal obligations, net 305.1 316.8 Other 3.8 4.7 Total non-current regulatory liabilities $ 1,247.7 $ 1,188.9 (A) Included in Other Current Assets in the balance sheets.
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following tables present changes in the components of accumulated other comprehensive income (loss) attributable to OGE Energy during the nine months ended September 30, 2021 and 2020. All amounts below are presented net of tax. (In millions) Pension Plan and Restoration of Retirement Income Plan Postretirement Benefit Plans Other Comprehensive Gain (Loss) from Unconsolidated Affiliates Total Balance at December 31, 2020 $ (34.1) $ 3.3 $ (1.3) $ (32.1) Other comprehensive income before reclassifications — — 0.6 0.6 Amounts reclassified from accumulated other comprehensive income (loss) 1.3 (0.9) — 0.4 Settlement cost 4.8 — — 4.8 Balance at September 30, 2021 $ (28.0) $ 2.4 $ (0.7) $ (26.3) (In millions) Pension Plan and Restoration of Retirement Income Plan Postretirement Benefit Plans Other Comprehensive Loss from Unconsolidated Affiliates Total Balance at December 31, 2019 $ (35.1) $ 7.8 $ (0.6) $ (27.9) Other comprehensive loss before reclassifications — — (0.9) (0.9) Amounts reclassified from accumulated other comprehensive income (loss) 2.9 (1.3) — 1.6 Settlement cost 1.5 — — 1.5 Balance at September 30, 2020 $ (30.7) $ 6.5 $ (1.5) $ (25.7)
Schedule of Amounts Reclassified out of Accumulated Other Comprehensive Income [Table Text Block]	The following table presents significant amounts reclassified out of accumulated other comprehensive income (loss) attributable to OGE Energy by the respective line items in net income (loss) during the three and nine months ended September 30, 2021 and 2020. Details about Accumulated Other Comprehensive Income (Loss) Components Amount Reclassified from Accumulated Other Comprehensive Income (Loss) Affected Line Item in Three Months Ended Nine Months Ended September 30, September 30, (In millions) 2021 2020 2021 2020 Amortization of Pension Plan Actuarial losses $ (0.6) $ (1.2) $ (1.8) $ (3.8) (A) Prior service cost (0.1) — (0.1) — (A) Settlement cost (1.4) (1.8) (6.7) (2.1) (A) (2.1) (3.0) (8.6) (5.9) Income (Loss) Before Taxes (0.5) (0.8) (2.5) (1.5) Income Tax Expense (Benefit) $ (1.6) $ (2.2) $ (6.1) $ (4.4) Net Income (Loss) Amortization of postretirement benefit plans items: Prior service credit $ 0.4 $ 0.6 $ 1.3 $ 1.7 (A) Actuarial gains (losses) — — (0.1) 0.1 (A) 0.4 0.6 1.2 1.8 Income (Loss) Before Taxes 0.1 0.2 0.3 0.5 Income Tax Expense (Benefit) $ 0.3 $ 0.4 $ 0.9 $ 1.3 Net Income (Loss) Total reclassifications for the period, net of tax $ (1.3) $ (1.8) $ (5.2) $ (3.1) Net Income (Loss) (A) These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost (see Note 12 for additional information).

Revenue from Contracts with C_2

Revenue from Contracts with Customers (Tables)	9 Months Ended
	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue [Table Text Block]	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 2. Management's Discussion and Analysis of Financial Condition and Results of Operations." Three Months Ended September 30, Nine Months Ended September 30, (In millions) 2021 2020 2021 2020 Residential $ 365.5 $ 294.9 $ 1,112.2 $ 664.6 Commercial 203.4 156.7 619.2 361.0 Industrial 79.9 59.3 264.1 145.5 Oilfield 68.0 50.6 257.5 127.2 Public authorities and street light 75.0 57.8 235.1 133.1 System sales revenues 791.8 619.3 2,488.1 1,431.4 Provision for rate refund — 4.8 — 3.2 Integrated market 17.2 18.0 447.6 33.7 Transmission 30.8 35.0 103.8 109.0 Other 8.4 10.7 (5.8) 22.9 Revenues from contracts with customers (A) $ 848.2 $ 687.8 $ 3,033.7 $ 1,600.2 (A) In February 2021, Winter Storm Uri resulted in record winter peak demand for electricity and extremely high natural gas and purchased power prices in OG&E's service territory. Operating revenues for the nine months ended September 30, 2021 significantly increased due to increased fuel, purchased power and direct transmission expenses, which are generally recoverable from customers, as a result of Winter Storm Uri. For further discussion, see Note 15 and "Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operation."

Investment in Unconsolidated _2

Investment in Unconsolidated Affiliates (Tables)	9 Months Ended
	Sep. 30, 2021
Reconciliation of Basis Difference [Line Items]
Reconciliation of Basis Difference [Table Text Block]	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, 2020 to September 30, 2021. The basis difference is amortized over approximately 30 years. (In millions) Basis difference at December 31, 2020 $ 1,332.3 Amortization of basis difference (A) (42.1) Basis difference at September 30, 2021 $ 1,290.2 (A) Includes proportional basis difference recognition due to dilution.
Reconciliation of Equity in Earnings of Unconsolidated Affiliates [Table Text Block]	The following table presents a reconciliation of OGE Energy's equity in earnings (losses) of unconsolidated affiliates for the three and nine months ended September 30, 2021 and 2020. For further discussion of Enable's net income (loss), see "Item 2. Management's Discussion and Analysis - Results of Operations - OGE Holdings (Natural Gas Midstream Operations)." Three Months Ended Nine Months Ended September 30, September 30, (In millions) 2021 2020 2021 2020 Enable net income (loss) $ 107.0 $ (173.0) $ 341.0 $ (35.0) OGE Energy's percent ownership at period end 25.5 % 25.5 % 25.5 % 25.5 % OGE Energy's portion of Enable net income (loss) $ 27.5 $ (44.0) $ 87.0 $ (8.9) Amortization of basis difference and dilution recognition (A) 13.7 59.8 40.9 85.1 Impairment of OGE Energy's equity method investment in Enable (B) — — — (780.0) Equity in earnings (losses) of unconsolidated affiliates (C) $ 41.2 $ 15.8 $ 127.9 $ (703.8) (A) Includes loss on dilution, net of proportional basis difference recognition. (B) 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 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 2020. Further discussion can be found in OGE Energy's 2020 Form 10-K . (C) For the three and nine months ended September 30, 2020, Enable recorded a $225.0 million impairment on its SESH equity method investment, which is included in their net loss for each period. 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 (loss) and was offset by basis differences that flow through the amortization of basis difference and dilution recognition line item above.
Schedule of Related Party Transactions [Table Text Block]	The following table presents summarized related party transactions between OG&E and Enable during the three and nine months ended September 30, 2021 and 2020. Three Months Ended Nine Months Ended September 30, September 30, (In millions) 2021 2020 2021 2020 Operating revenues: Electricity to power electric compression assets $ 4.1 $ 4.5 $ 10.0 $ 11.7 Fuel, purchased power and direct transmission expense: Natural gas transportation services $ 9.4 $ 9.3 $ 23.4 $ 23.4 Natural gas purchases (sales) $ (7.7) $ 3.2 $ (28.3) $ 2.2
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 September 30, 2021 and December 31, 2020 and for the three and nine months ended September 30, 2021 and 2020. September 30, December 31, Balance Sheet 2021 2020 (In millions) Current assets $ 536 $ 381 Non-current assets $ 11,244 $ 11,348 Current liabilities $ 1,299 $ 582 Non-current liabilities $ 3,248 $ 4,052
Summarized Income Statement Financial Information, Equity Method Investment [Table Text Block]	Three Months Ended Nine Months Ended September 30, September 30, Income Statement 2021 2020 2021 2020 (In millions) Total revenues $ 956 $ 596 $ 2,713 $ 1,759 Cost of natural gas and NGLs (excluding depreciation and amortization) $ 565 $ 250 $ 1,510 $ 653 Operating income $ 152 $ 100 $ 482 $ 326 Net income (loss) $ 107 $ (173) $ 341 $ (35)

Related Party Disclosures (Tabl

Related Party Disclosures (Tables)	9 Months Ended
	Sep. 30, 2021
Related Party Transactions [Abstract]
Schedule of Related Party Transactions [Table Text Block]	The following table presents summarized related party transactions between OG&E and Enable during the three and nine months ended September 30, 2021 and 2020. Three Months Ended Nine Months Ended September 30, September 30, (In millions) 2021 2020 2021 2020 Operating revenues: Electricity to power electric compression assets $ 4.1 $ 4.5 $ 10.0 $ 11.7 Fuel, purchased power and direct transmission expense: Natural gas transportation services $ 9.4 $ 9.3 $ 23.4 $ 23.4 Natural gas purchases (sales) $ (7.7) $ 3.2 $ (28.3) $ 2.2

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Fair Value and Carrying Amount of PRM Financial Instruments [Table Text Block]	The following table presents the carrying amount and fair value of the Registrants' financial instruments at September 30, 2021 and December 31, 2020, as well as the classification level within the fair value hierarchy. September 30, December 31, 2021 2020 (In millions) Carrying Amount Fair Carrying Amount Fair Classification Long-term Debt (including Long-term Debt due within one year): OGE Energy Senior Notes $ 499.9 $ 500.1 $ — $ — Level 2 OG&E Senior Notes $ 3,851.1 $ 4,503.4 $ 3,349.6 $ 4,182.1 Level 2 OG&E Industrial Authority Bonds $ 135.4 $ 135.4 $ 135.4 $ 135.4 Level 2 OG&E Tinker Debt $ 9.4 $ 10.0 $ 9.4 $ 10.7 Level 3

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Payment Arrangement, Cost by Plan [Table Text Block]	The following table presents the Registrants' pre-tax compensation expense and related income tax benefit for the three and nine months ended September 30, 2021 and 2020 related to performance units and restricted stock units for the Registrants' employees. OGE Energy OG&E Three Months Ended September 30, Nine Months Ended September 30, Three Months Ended September 30, Nine Months Ended September 30, (In millions) 2021 2020 2021 2020 2021 2020 2021 2020 Performance units: Total shareholder return $ 1.9 $ 1.9 $ 5.8 $ 5.6 $ 0.5 $ 0.5 $ 1.4 $ 1.8 Earnings per share — 0.2 — 0.5 — — — 0.1 Total performance units 1.9 2.1 5.8 6.1 0.5 0.5 1.4 1.9 Restricted stock units 0.4 0.3 1.3 0.6 0.1 0.1 0.2 0.3 Total compensation expense $ 2.3 $ 2.4 $ 7.1 $ 6.7 $ 0.6 $ 0.6 $ 1.6 $ 2.2 Income tax benefit $ 0.6 $ 0.6 $ 1.8 $ 1.7 $ 0.1 $ 0.2 $ 0.4 $ 0.6

Common Equity (Tables)

Common Equity (Tables)	9 Months Ended
	Sep. 30, 2021
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. Three Months Ended September 30, Nine Months Ended September 30, (In millions except per share data) 2021 2020 2021 2020 Net income (loss) $ 252.5 $ 177.4 $ 418.1 $ (228.5) Average common shares outstanding: Basic average common shares outstanding 200.2 200.1 200.1 200.1 Effect of dilutive securities: Contingently issuable shares (performance and restricted stock units) 0.2 0.3 0.2 — Diluted average common shares outstanding 200.4 200.4 200.3 200.1 Basic earnings (loss) per average common share $ 1.26 $ 0.89 $ 2.09 $ (1.14) Diluted earnings (loss) per average common share $ 1.26 $ 0.89 $ 2.09 $ (1.14) Anti-dilutive shares excluded from earnings per share calculation — — — 0.3

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2021
Long-term Debt, Unclassified [Abstract]
Schedule of Long-term Debt Instruments [Table Text Block]	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) 0.11% - 0.27% Garfield Industrial Authority, January 1, 2025 $ 47.0 0.11% - 0.33% Muskogee Industrial Authority, January 1, 2025 32.4 0.11% - 0.27% Muskogee Industrial Authority, June 1, 2027 56.0 Total (redeemable during next 12 months) $ 135.4

Short-Term Debt and Credit Fa_2

Short-Term Debt and Credit Facilities (Tables)	9 Months Ended
	Sep. 30, 2021
Short-term Debt [Abstract]
Schedule of Line of Credit Facilities [Table Text Block]	The following table presents information regarding the Registrants' revolving credit agreements at September 30, 2021. Aggregate Amount Weighted-Average Entity Commitment Outstanding (A) Interest Rate Expiration (In millions) OGE Energy (B) $ 450.0 $ 283.2 0.18 % (E) March 8, 2024 (F) OG&E (C)(D) 450.0 0.4 1.15 % (E) March 8, 2024 (F) Total $ 900.0 $ 283.6 0.18 % (A) Includes direct borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit at September 30, 2021. (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) 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 September 30, 2021, there were no intercompany borrowings under this agreement. (E) Represents the weighted-average interest rate for the outstanding borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit. (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-

Retirement Plans and Postreti_2

Retirement Plans and Postretirement Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Schedule of Defined Benefit Plans Disclosures [Table Text Block]	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 condensed financial statements. Service cost is presented within Other Operation and Maintenance Expense, and the remaining net periodic benefit cost components as listed in the following tables are presented within Other Net Periodic Benefit 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 Expense in the statements of income. Pension Plan Restoration of Retirement Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended OGE Energy September 30, September 30, September 30, September 30, (In millions) 2021 2020 2021 2020 2021 2020 2021 2020 Service cost $ 2.8 $ 3.3 $ 8.4 $ 9.8 $ 0.3 $ 0.2 $ 0.6 $ 0.6 Interest cost 3.1 4.2 10.0 13.4 — 0.1 0.1 0.2 Expected return on plan assets (8.5) (9.4) (25.6) (28.0) — — — — Amortization of net loss 2.3 4.3 7.0 12.7 — 0.1 0.1 0.4 Amortization of unrecognized prior service cost (A) — — — — 0.1 — 0.1 — Settlement cost 3.7 12.1 35.4 12.1 1.7 0.4 2.1 0.7 Total net periodic benefit cost 3.4 14.5 35.2 20.0 2.1 0.8 3.0 1.9 Less: Amount paid by unconsolidated affiliates (B) (0.1) 0.5 (0.2) 1.6 — 0.1 — 0.1 Net periodic benefit cost $ 3.5 $ 14.0 $ 35.4 $ 18.4 $ 2.1 $ 0.7 $ 3.0 $ 1.8 Pension Plan Restoration of Retirement Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended OG&E September 30, September 30, September 30, September 30, (In millions) 2021 2020 2021 2020 2021 2020 2021 2020 Service cost $ 2.0 $ 2.3 $ 5.8 $ 6.8 $ — $ — $ — $ 0.1 Interest cost 2.3 3.2 7.3 10.0 — — — 0.1 Expected return on plan assets (6.2) (7.0) (18.5) (20.9) — — — — Amortization of net loss 1.7 3.0 5.2 9.0 — 0.1 0.1 0.3 Settlement cost 2.6 10.3 29.2 10.3 1.3 0.5 1.6 0.5 Total net periodic benefit cost 2.4 11.8 29.0 15.2 1.3 0.6 1.7 1.0 Plus: Amount allocated from OGE Energy (B) 0.7 1.5 5.3 2.5 0.8 0.2 1.3 0.8 Net periodic benefit cost $ 3.1 $ 13.3 $ 34.3 $ 17.7 $ 2.1 $ 0.8 $ 3.0 $ 1.8 (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 tables above, for the Pension and Restoration of Retirement Income Plans for the three and nine months ended September 30, 2021 and 2020, the Registrants recognized the following: Three Months Ended September 30, Nine Months Ended September 30, (In millions) 2021 2020 2021 2020 Increase of pension expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A) $ 3.9 $ 2.4 $ 11.1 $ 5.7 Deferral of pension expense related to pension settlement charges: Oklahoma jurisdiction (A) $ 4.4 $ 10.8 $ 33.3 $ 11.1 Arkansas jurisdiction (A) $ 0.4 $ 1.0 $ 3.1 $ 1.0 (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 Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, (In millions) 2021 2020 2021 2020 2021 2020 2021 2020 Service cost $ 0.1 $ 0.1 $ 0.2 $ 0.2 $ — $ — $ 0.1 $ 0.1 Interest cost 0.9 1.0 2.6 3.1 0.6 0.8 1.9 2.4 Expected return on plan assets (0.4) (0.5) (1.4) (1.4) (0.4) (0.4) (1.3) (1.2) Amortization of net loss 0.7 0.5 2.1 1.5 0.6 0.5 2.0 1.6 Amortization of unrecognized prior service cost (A) (1.8) (2.1) (5.2) (6.3) (1.2) (1.5) (3.7) (4.6) Total net periodic benefit cost (0.5) (1.0) (1.7) (2.9) (0.4) (0.6) (1.0) (1.7) Less: Amount paid by unconsolidated affiliates (B) (0.1) (0.2) (0.4) (0.6) Plus: Amount allocated from OGE Energy (B) (0.1) (0.2) (0.3) (0.6) Net periodic benefit cost $ (0.4) $ (0.8) $ (1.3) $ (2.3) $ (0.5) $ (0.8) $ (1.3) $ (2.3) (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 for the three and nine months ended September 30, 2021 and 2020, the Registrants recognized the following: Three Months Ended September 30, Nine Months Ended September 30, (In millions) 2021 2020 2021 2020 Increase of postretirement expense to maintain allowed recoverable amount in Oklahoma jurisdiction (A) $ 0.1 $ 0.4 $ 0.3 $ 1.2
Schedule of Capitalized Pension and Postretirement Cost [Table Text Block]	OGE Energy OG&E Three Months Ended Nine Months Ended Three Months Ended Nine Months Ended September 30, September 30, September 30, September 30, (In millions) 2021 2020 2021 2020 2021 2020 2021 2020 Capitalized portion of net periodic pension benefit cost $ 0.9 $ 0.9 $ 2.5 $ 2.7 $ 0.7 $ 0.8 $ 2.1 $ 2.3 Capitalized portion of net periodic postretirement benefit cost $ 0.1 $ — $ 0.2 $ 0.1 $ — $ — $ 0.1 $ 0.1

Report of Business Segments (Ta

Report of Business Segments (Tables)	9 Months Ended
	Sep. 30, 2021
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 three and nine months ended September 30, 2021 and 2020. Three Months Ended September 30, 2021 Electric Utility Natural Gas Midstream Operations Other Eliminations Total (In millions) Operating revenues $ 864.4 $ — $ — $ — $ 864.4 Fuel, purchased power and direct transmission expense 330.1 — — — 330.1 Other operation and maintenance 115.8 0.3 (0.7) — 115.4 Depreciation and amortization 108.6 — — — 108.6 Taxes other than income 24.6 0.1 0.8 — 25.5 Operating income (loss) 285.3 (0.4) (0.1) — 284.8 Equity in earnings of unconsolidated affiliates — 41.2 — — 41.2 Other income (expense) 2.9 (0.5) (0.2) (0.1) 2.1 Interest expense 38.0 — 1.6 (0.1) 39.5 Income tax expense 26.4 9.5 0.2 — 36.1 Net income (loss) $ 223.8 $ 30.8 $ (2.1) $ — $ 252.5 Investment in unconsolidated affiliates $ — $ 449.5 $ 29.4 $ — $ 478.9 Total assets $ 11,597.9 $ 451.8 $ 293.3 $ (165.5) $ 12,177.5 Three Months Ended September 30, 2020 Electric Utility Natural Gas Midstream Operations Other Eliminations Total (In millions) Operating revenues $ 702.1 $ — $ — $ — $ 702.1 Fuel, purchased power and direct transmission expense 209.1 — — — 209.1 Other operation and maintenance 110.1 0.3 (0.7) — 109.7 Depreciation and amortization 100.5 — — — 100.5 Taxes other than income 23.9 0.2 0.7 — 24.8 Operating income (loss) 258.5 (0.5) — — 258.0 Equity in earnings of unconsolidated affiliates — 15.8 — — 15.8 Other income (expense) 0.6 (0.7) (0.5) (0.2) (0.8) Interest expense 39.5 — 0.5 (0.2) 39.8 Income tax expense 20.1 4.5 31.2 — 55.8 Net income (loss) $ 199.5 $ 10.1 $ (32.2) $ — $ 177.4 Investment in unconsolidated affiliates $ — $ 355.8 $ 21.0 $ — $ 376.8 Total assets $ 10,323.3 $ 358.7 $ 109.6 $ (294.0) $ 10,497.6 Nine Months Ended September 30, 2021 Electric Utility Natural Gas Midstream Operations Other Eliminations Total (In millions) Operating revenues $ 3,072.4 $ — $ — $ — $ 3,072.4 Fuel, purchased power and direct transmission expense 1,876.9 — — — 1,876.9 Other operation and maintenance 344.4 2.3 (2.8) — 343.9 Depreciation and amortization 310.2 — — — 310.2 Taxes other than income 75.3 0.3 2.9 — 78.5 Operating income (loss) 465.6 (2.6) (0.1) — 462.9 Equity in earnings of unconsolidated affiliates — 127.9 — — 127.9 Other income (expense) 5.8 (1.2) (0.8) (0.9) 2.9 Interest expense 114.3 — 5.4 (0.9) 118.8 Income tax expense (benefit) 37.0 23.2 (3.4) — 56.8 Net income (loss) $ 320.1 $ 100.9 $ (2.9) $ — $ 418.1 Investment in unconsolidated affiliates $ — $ 449.5 $ 29.4 $ — $ 478.9 Total assets $ 11,597.9 $ 451.8 $ 293.3 $ (165.5) $ 12,177.5 Nine Months Ended September 30, 2020 Electric Utility Natural Gas Midstream Operations Other Eliminations Total (In millions) Operating revenues $ 1,636.9 $ — $ — $ — $ 1,636.9 Fuel, purchased power and direct transmission expense 481.5 — — — 481.5 Other operation and maintenance 348.8 1.2 (2.8) — 347.2 Depreciation and amortization 292.2 — — — 292.2 Taxes other than income 72.8 0.4 3.1 — 76.3 Operating income (loss) 441.6 (1.6) (0.3) — 439.7 Equity in losses of unconsolidated affiliates (A) — (703.8) — — (703.8) Other income (expense) 2.9 (0.7) 2.5 (1.4) 3.3 Interest expense 115.7 — 4.6 (1.4) 118.9 Income tax expense (benefit) 30.5 (167.2) (14.5) — (151.2) Net income (loss) $ 298.3 $ (538.9) $ 12.1 $ — $ (228.5) Investment in unconsolidated affiliates $ — $ 355.8 $ 21.0 $ — $ 376.8 Total assets $ 10,323.3 $ 358.7 $ 109.6 $ (294.0) $ 10,497.6

Summary of Significant Accoun_4

Summary of Significant Accounting Policies Equity Ownership (Details)	Sep. 30, 2021
CenterPoint [Member]
Percentage Share of Management Rights	50.00%
OGE Energy [Member]
Percentage Share of Management Rights	50.00%

Regulated Operations (Details)

Regulated Operations (Details) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Schedule of Regulatory Assets and Liabilities [Line Items]
Fuel clause under recoveries		$ 98.2	$ 0
Current Regulatory Assets		115.3	19.8
Non-Current Regulatory Assets		1,264.9	415.6
Current Regulatory Liabilities		6.3	35.1
Fuel clause over recoveries		0	28.6
Non-Current Regulatory Liabilities		1,247.7	1,188.9
Oklahoma Demand Program Over Recovery [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current Regulatory Liabilities	[1]	4.7	1.5
Other (B)
Schedule of Regulatory Assets and Liabilities [Line Items]
Current Regulatory Liabilities	[1]	1.6	5
Non-Current Regulatory Liabilities		3.8	4.7
Income taxes recoverable from customers, net
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Liabilities		938.8	867.4
Accrued removal obligations, net
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Liabilities		305.1	316.8
Benefit obligations regulatory asset
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		130.6	164.9
Oklahoma deferred storm expenses
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		173.8	158.8
Smart Grid
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		5.9	11.2
Dry Scrubber Regulatory Asset [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		19.1	19.7
Unamortized loss on reacquired debt
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		9.1	9.7
Deferred Pension Expenses [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		11.8	9.3
Other Regulatory Asset [Member]
Schedule of Regulatory Assets and Liabilities [Line Items]
Current Regulatory Assets	[2]	7.7	8.4
Non-Current Regulatory Assets		10.6	11.1
Pension tracker
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		41.6	18.1
SPP Cost Tracker Rider Under Recovery
Schedule of Regulatory Assets and Liabilities [Line Items]
Current Regulatory Assets	[2]	7.7	7
COVID-19 Deferred Expenses
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		8	6.4
Extreme Cold Weather Costs | OKLAHOMA
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		756.3	0
Extreme Cold Weather Costs | ARKANSAS
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		91	0
Frontier Plant
Schedule of Regulatory Assets and Liabilities [Line Items]
Non-Current Regulatory Assets		7.1	6.4
Generation Capacity Replacement
Schedule of Regulatory Assets and Liabilities [Line Items]
Current Regulatory Assets	[2]	$ 1.7	$ 4.4
[1]	Included in Other Current Liabilities in the balance sheets.
[2]	Included in Other Current Assets in the balance sheets.

Summary of Significant Accoun_5

Summary of Significant Accounting Policies Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (26.3)	$ (25.7)	$ (32.1)	$ (27.9)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0.6	(0.9)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0.4	1.6
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member] | Pension Plan [Member]
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	(28)	(30.7)	(34.1)	(35.1)
Other Comprehensive Income (Loss), before Reclassifications, before Tax	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	1.3	2.9
Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member] | Other Postretirement Benefits Plan [Member]
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	2.4	6.5	3.3	7.8
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(0.9)	(1.3)
Commodity Contract [Member]
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	0.6	(0.9)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(0.7)	(1.5)	$ (1.3)	$ (0.6)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Settlement Cost [Member]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	4.8	1.5
Settlement Cost [Member] | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member] | Pension Plan [Member]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	4.8	1.5
Settlement Cost [Member] | Accumulated Defined Benefit Plans Adjustment, Net Unamortized Gain (Loss) [Member] | Other Postretirement Benefits Plan [Member]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Settlement Cost [Member] | Commodity Contract [Member]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 0	$ 0

Summary of Significant Accoun_6

Summary of Significant Accounting Policies Accumulated Other Comprehensive Income (Loss) Reclassifications out of AOCI (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent		$ (1.3)	$ (1.8)	$ (5.2)	$ (3.1)
Pension Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	[1]	(0.6)	(1.2)	(1.8)	(3.8)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	[1]	(0.1)	0	(0.1)	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax	[1]	(1.4)	(1.8)	(6.7)	(2.1)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax		(2.1)	(3)	(8.6)	(5.9)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax		(0.5)	(0.8)	(2.5)	(1.5)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax		(1.6)	(2.2)	(6.1)	(4.4)
Other Postretirement Benefits Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	[1]	0	0	(0.1)	0.1
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	[1]	0.4	0.6	1.3	1.7
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax		0.4	0.6	1.2	1.8
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax		0.1	0.2	0.3	0.5
Amounts reclassified from accumulated other comprehensive income (loss), net of tax		$ 0.3	$ 0.4	$ 0.9	$ 1.3
[1]	These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost (see Note 12 for additional information).

Revenue from Contracts with C_3

Revenue from Contracts with Customers (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	[1]	$ 848.2	$ 687.8	$ 3,033.7	$ 1,600.2
Residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		365.5	294.9	1,112.2	664.6
Commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		203.4	156.7	619.2	361
Industrial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		79.9	59.3	264.1	145.5
Oilfield
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		68	50.6	257.5	127.2
Public authorities and street light
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		75	57.8	235.1	133.1
System sales revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		791.8	619.3	2,488.1	1,431.4
Provision for rate refund
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		0	4.8	0	3.2
Integrated market
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		17.2	18	447.6	33.7
Transmission
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		30.8	35	103.8	109
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers		$ 8.4	$ 10.7	$ (5.8)	$ 22.9
[1]	In February 2021, Winter Storm Uri resulted in record winter peak demand for electricity and extremely high natural gas and purchased power prices in OG&E's service territory. Operating revenues for the nine months ended September 30, 2021 significantly increased due to increased fuel, purchased power and direct transmission expenses, which are generally recoverable from customers, as a result of Winter Storm Uri. For further discussion, see Note 15 and "Item 2. Management's Discussion and Analysis of Financial Condition and Results of Operation."

Investment in Unconsolidated _3

Investment in Unconsolidated Affiliates (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020		Dec. 31, 2020
Limited Partner Units Owned		111		111
Distribution Made to Limited Partner, Distributions Declared, Per Unit				$ 0.16525
Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest		25.50%	25.50%	25.50%	25.50%
Equity in earnings (losses) of unconsolidated affiliates	[1]	$ 41.2	$ 15.8	$ 127.9	$ (703.8)	[2]
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity		1,290.2		1,290.2			$ 1,332.3
Enable Midstream Partners [Member]
Distributions from unconsolidated affiliates		$ 18.3	$ 18.3	$ 55	$ 73.3
OGE Holdings [Member]
Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest				25.50%
Energy Transfer
Common Stock, Terms of Conversion				0.8595
Enable Midstream Partners [Member]
Share Price		$ 8.12		$ 8.12
[1]	For the three and nine months ended September 30, 2020, Enable recorded a $225.0 million impairment on its SESH equity method investment, which is included in their net loss for each period. 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 (loss) and was offset by basis differences that flow through the amortization of basis difference and dilution recognition line item above.
[2]	In 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Note 4

Investment in Unconsolidated _4

Investment in Unconsolidated Affiliates Summarized Balance Sheet Information of Equity Method Investment (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Assets, Current	$ 627	$ 428.5
Liabilities, Current	993.9	697.4
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Schedule of Equity Method Investments [Line Items]
Assets, Current	536	381
Assets, Noncurrent	11,244	11,348
Liabilities, Current	1,299	582
Liabilities, Noncurrent	$ 3,248	$ 4,052

Investment in Unconsolidated _5

Investment in Unconsolidated Affiliates Summarized Income Statement of Equity Method Investment (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Schedule of Equity Method Investments [Line Items]
Operating revenues	$ 864.4			$ 702.1			$ 3,072.4	$ 1,636.9
Operating Income (Loss)	284.8			258			462.9	439.7
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	252.5	$ 112.9	$ 52.7	177.4	$ 85.9	$ (491.8)	418.1	(228.5)
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Schedule of Equity Method Investments [Line Items]
Operating revenues	956			596			2,713	1,759
Cost of Revenue	565			250			1,510	653
Operating Income (Loss)	152			100			482	326
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 107			$ (173)			$ 341	$ (35)

Investment in Unconsolidated _6

Investment in Unconsolidated Affiliates Reconciliation of Equity in Earnings of Unconsolidated Affiliates (Details) - USD ($) $ in Millions		3 Months Ended						9 Months Ended
		Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020		Dec. 31, 2020
Reconciliation of Equity in Earnings of Unconsolidated Affiliates [Line Items]
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity		$ 1,290.2						$ 1,290.2			$ 1,332.3
Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest		25.50%			25.50%			25.50%	25.50%
Proportionate Unconsolidated Affiliate Net Income		$ 27.5			$ (44)			$ 87	$ (8.9)
Equity in Earnings Amortization of Basis Difference	[1]	13.7			59.8			40.9	85.1
Income (Loss) from Equity Method Investments, Total	[2]	41.2			15.8			127.9	(703.8)	[3]
Asset Impairment Charges	[4]	0			0			0	(780)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		252.5	$ 112.9	$ 52.7	177.4	$ 85.9	$ (491.8)	418.1	(228.5)
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Reconciliation of Equity in Earnings of Unconsolidated Affiliates [Line Items]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest		$ 107			$ (173)			$ 341	$ (35)
OGE Holdings [Member]
Reconciliation of Equity in Earnings of Unconsolidated Affiliates [Line Items]
Limited Liability Company or Limited Partnership, Members or Limited Partners, Ownership Interest								25.50%
OGE Energy [Member]
Reconciliation of Equity in Earnings of Unconsolidated Affiliates [Line Items]
Equity in Earnings Amortization of Basis Difference	[5]							$ 42.1
[1]	Includes loss on dilution, net of proportional basis difference recognition.
[2]	For the three and nine months ended September 30, 2020, Enable recorded a $225.0 million impairment on its SESH equity method investment, which is included in their net loss for each period. 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 (loss) and was offset by basis differences that flow through the amortization of basis difference and dilution recognition line item above.
[3]	In 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Note 4
[4]	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 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 2020. Further discussion can be found in OGE Energy's 2020 Form 10-K .
[5]	Includes proportional basis difference recognition due to dilution.

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Related Party Transaction [Line Items]
Expected Settlement Charge			$ 17.6
Enable Midstream Partners [Member] | OG&E [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	$ (4.1)	$ (4.5)	(10)	$ (11.7)
OG&E [Member] | OGE Energy [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party	32.2	32.7	101.3	107.5
Operating Costs Charged [Member] | Enable Midstream Partners [Member] | OGE Energy [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party	0.1	0.1	0.3	0.3
Employment Costs [Member] | Enable Midstream Partners [Member] | OGE Energy [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party	2.5	3.5	10.3	13.6
Natural Gas Transportation [Member] | Enable Midstream Partners [Member] | OG&E [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	9.4	9.3	23.4	23.4
Natural Gas Purchases [Member] | Enable Midstream Partners [Member] | OG&E [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	(7.7)	$ 3.2	(28.3)	$ 2.2
Excluding Fuel Purchases [Member]
Related Party Transaction [Line Items]
Accounts receivable - unconsolidated affiliates	$ 1.1		$ 1.1		$ 2

Fair Value Measurements Carryin

Fair Value Measurements Carrying and Fair Value Amounts (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
OG&E Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-Term Debt, Carrying Amount	$ 3,851.1	$ 3,349.6
Long-Term Debt, Fair Value	4,503.4	4,182.1
OG&E Industrial Authority Bonds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-Term Debt, Carrying Amount	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]
Long-Term Debt, Carrying Amount	9.4	9.4
Long-Term Debt, Fair Value	10	10.7
OGE Energy [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-Term Debt, Carrying Amount	499.9	0
Long-Term Debt, Fair Value	500.1	0
Fair Value, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	$ 0	$ 0

Stock-Based Compensation (Detai

Stock-Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Stock-Based Compensation Activity
Income tax benefit	$ 0.6	$ 0.6	$ 1.8	$ 1.7
Treasury Stock, Shares, Acquired			154,523
OG&E [Member]
Stock-Based Compensation Activity
Income tax benefit	0.1	0.2	$ 0.4	0.6
Performance Shares [Member]
Stock-Based Compensation Activity
Compensation expense	1.9	2.1	5.8	6.1
Performance Shares [Member] | Total Shareholder Return [Member]
Stock-Based Compensation Activity
Compensation expense	1.9	1.9	5.8	5.6
Performance Shares [Member] | Performance Units Related to Earnings Per Share [Member]
Stock-Based Compensation Activity
Compensation expense	0	0.2	0	0.5
Performance Shares [Member] | OG&E [Member]
Stock-Based Compensation Activity
Compensation expense	0.5	0.5	1.4	1.9
Performance Shares [Member] | OG&E [Member] | Total Shareholder Return [Member]
Stock-Based Compensation Activity
Compensation expense	0.5	0.5	1.4	1.8
Performance Shares [Member] | OG&E [Member] | Performance Units Related to Earnings Per Share [Member]
Stock-Based Compensation Activity
Compensation expense	0	0	0	0.1
Restricted stock units
Stock-Based Compensation Activity
Compensation expense	0.4	0.3	1.3	0.6
Restricted stock units | OG&E [Member]
Stock-Based Compensation Activity
Compensation expense	0.1	0.1	0.2	0.3
Share-based Payment Arrangement [Member]
Stock-Based Compensation Activity
Compensation expense	2.3	2.4	7.1	6.7
Share-based Payment Arrangement [Member] | OG&E [Member]
Stock-Based Compensation Activity
Compensation expense	$ 0.6	$ 0.6	$ 1.6	$ 2.2

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Non-Current Regulatory Liabilities	$ 1,247.7	$ 1,188.9
OG&E [Member]
Non-Current Regulatory Liabilities	1,247.7	$ 1,188.9
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	97.7
OGE Energy [Member]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	$ 6.6

Common Equity Automatic Dividen

Common Equity Automatic Dividend Reinvestment and Stock Purchase Plan (Details) - shares	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021
Automatic Dividend Reinvestment and Stock Purchase Plan [Member]
Stock Issued During Period, Shares, New Issues	0	0

Common Equity Earnings Per Shar

Common Equity Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Equity [Abstract]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 252.5	$ 112.9	$ 52.7	$ 177.4	$ 85.9	$ (491.8)	$ 418.1	$ (228.5)
Basic average common shares outstanding	200.2			200.1			200.1	200.1
Contingently issuable shares (performance and restricted stock units)	0.2			0.3			0.2	0
Diluted average common shares outstanding	200.4			200.4			200.3	200.1
Earnings Per Share, Basic and Diluted [Abstract]
Basic earnings (loss) per average common share	$ 1.26			$ 0.89			$ 2.09	$ (1.14)
Diluted earnings (loss) per average common share	$ 1.26			$ 0.89			$ 2.09	$ (1.14)
Anti-dilutive shares excluded from earnings per share calculation	0			0			0	0.3

Long-Term Debt (Details)

Long-Term Debt (Details) $ in Millions	9 Months Ended
	Sep. 30, 2021USD ($)
Debt Instrument [Line Items]
Percent of Principal Amount Subject to Optional Tender	100.00%
Debt Instrument, Face Amount	$ 1,000
Garfield Industrial Authority Bond [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Jan. 1, 2025
Muskogee Industrial Authority Bond Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Jan. 1, 2025
Muskogee Industrial Authority Bond Due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Jun. 1, 2027
Redeemable during the next 12 months
Debt Instrument [Line Items]
Long-term Debt	$ 135.4
OG&E [Member] | Redeemable during the next 12 months | Garfield Industrial Authority Bond [Member]
Debt Instrument [Line Items]
Long term debt	47
OG&E [Member] | Redeemable during the next 12 months | Muskogee Industrial Authority Bond Due 2025 [Member]
Debt Instrument [Line Items]
Long term debt	32.4
OG&E [Member] | Redeemable during the next 12 months | Muskogee Industrial Authority Bond Due 2027 [Member]
Debt Instrument [Line Items]
Long term debt	$ 56
Minimum [Member] | Redeemable during the next 12 months | Garfield Industrial Authority Bond [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.11%
Minimum [Member] | Redeemable during the next 12 months | Muskogee Industrial Authority Bond Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.11%
Minimum [Member] | Redeemable during the next 12 months | Muskogee Industrial Authority Bond Due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.11%
Maximum [Member] | Redeemable during the next 12 months | Garfield Industrial Authority Bond [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.27%
Maximum [Member] | Redeemable during the next 12 months | Muskogee Industrial Authority Bond Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.33%
Maximum [Member] | Redeemable during the next 12 months | Muskogee Industrial Authority Bond Due 2027 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.27%
Senior Notes | OG&E [Member] | Series Due May 26, 2023
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.553%
Debt Instrument, Maturity Date	May 26, 2023
Debt Instrument, Face Amount	$ 500
Senior Notes | OGE Energy [Member] | Series Due May 26, 2023
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	0.703%
Debt Instrument, Maturity Date	May 26, 2023
Debt Instrument, Face Amount	$ 500

Short-Term Debt and Credit Fa_3

Short-Term Debt and Credit Facilities (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
		Mar. 31, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Line of Credit Facility [Line Items]
Short-term debt			$ 383.2		$ 95
Line of Credit Facility [Abstract]
Aggregate Commitment			900
Long-term Line of Credit	[1]		$ 283.6
Weighted Average Interest Rate			0.18%
Debt Instrument, Face Amount			$ 1,000
Proceeds from Contributed Capital		$ 530
Debt, Weighted Average Interest Rate			0.832%
OGE Energy [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	[2]		$ 450
Line of Credit Facility [Abstract]
Long-term Line of Credit	[1],[2]		$ 283.2
Weighted Average Interest Rate	[2],[3]		0.18%
Maturity	[2],[4]		Mar. 8, 2024
OGE Energy [Member] | Not Extended
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity			$ 50
Line of Credit Facility [Abstract]
Maturity			Mar. 8, 2023
OG&E [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	[5],[6]		$ 450
Line of Credit Facility [Abstract]
Letters of Credit Outstanding, Amount	[1],[5],[6]		$ 0.4
Weighted Average Interest Rate	[3],[5],[6]		1.15%
Maturity	[4],[5],[6]		Mar. 8, 2024
Short Term Borrowing Capacity That Has Regulatory Approval			$ 800
Period For Which Regulatory Approval Has Been Given to Acquire Short Term Debt			2 years
Intercompany borrowing agreement, maximum borrowing capacity			$ 350
Outstanding intercompany borrowings			0
Proceeds from Loans			470
Advances from parent			42.2		0
Advances to parent			0		$ 272
Proceeds from Contributed Capital		$ 530	$ 530	$ 0
[1]	Includes direct borrowings under the revolving credit agreements, commercial paper borrowings and letters of credit at September 30, 2021.
[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 September 30, 2021, 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 Postreti_3

Retirement Plans and Postretirement Benefit Plans (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan, Plan Assets, Contributions by Employer				$ 40
Pension Plan [Member]
Other Comprehensive Income (Loss), Defined Benefit Plan, Adjustment for Settlement or Curtailment Gain (Loss), Tax		$ 0.3	$ 0.5	1.9	$ 0.6
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		2.8	3.3	8.4	9.8
Interest cost		3.1	4.2	10	13.4
Expected return on plan assets		(8.5)	(9.4)	(25.6)	(28)
Amortization of net loss		2.3	4.3	7	12.7
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		0	0	0	0
Settlement cost		3.7	12.1	35.4	12.1
Total net periodic benefit cost		3.4	14.5	35.2	20
Amount Attributable to Unconsolidated Affiliates	[1]	(0.1)	0.5	(0.2)	1.6
Net periodic benefit cost		3.5	14	35.4	18.4
Capitalized portion of net periodic pension benefit cost		0.9	0.9	2.5	2.7
Other Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		0.3	0.2	0.6	0.6
Interest cost		0	0.1	0.1	0.2
Expected return on plan assets		0	0	0	0
Amortization of net loss		0	0.1	0.1	0.4
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		0.1	0	0.1	0
Settlement cost		1.7	0.4	2.1	0.7
Total net periodic benefit cost		2.1	0.8	3	1.9
Amount Attributable to Unconsolidated Affiliates	[1]	0	0.1	0	0.1
Net periodic benefit cost		2.1	0.7	3	1.8
Postretirement Benefit Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		0.1	0.1	0.2	0.2
Interest cost		0.9	1	2.6	3.1
Expected return on plan assets		(0.4)	(0.5)	(1.4)	(1.4)
Amortization of net loss		0.7	0.5	2.1	1.5
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	[2]	(1.8)	(2.1)	(5.2)	(6.3)
Total net periodic benefit cost		(0.5)	(1)	(1.7)	(2.9)
Amount Attributable to Unconsolidated Affiliates	[1]	(0.1)	(0.2)	(0.4)	(0.6)
Net periodic benefit cost		(0.4)	(0.8)	(1.3)	(2.3)
Capitalized portion of net periodic pension benefit cost		0.1	0	0.2	0.1
OKLAHOMA | Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement cost	[3]	4.4	10.8	33.3	11.1
Additional Pension Expense to Meet State Requirements	[3]	3.9	2.4	11.1	5.7
OKLAHOMA | Postretirement Benefit Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Additional Pension Expense to Meet State Requirements	[4]	0.1	0.4	0.3	1.2
ARKANSAS | Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Settlement cost	[3]	0.4	1	3.1	1
OG&E [Member]
Defined Benefit Plan, Plan Assets, Contributions by Employer				30
OG&E [Member] | Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		2	2.3	5.8	6.8
Interest cost		2.3	3.2	7.3	10
Expected return on plan assets		(6.2)	(7)	(18.5)	(20.9)
Amortization of net loss		1.7	3	5.2	9
Settlement cost		2.6	10.3	29.2	10.3
Total net periodic benefit cost		2.4	11.8	29	15.2
Amount attributable to parent	[1]	0.7	1.5	5.3	2.5
Net periodic benefit cost		3.1	13.3	34.3	17.7
Capitalized portion of net periodic pension benefit cost		0.7	0.8	2.1	2.3
OG&E [Member] | Other Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		0	0	0	0.1
Interest cost		0	0	0	0.1
Expected return on plan assets		0	0	0	0
Amortization of net loss		0	0.1	0.1	0.3
Settlement cost		1.3	0.5	1.6	0.5
Total net periodic benefit cost		1.3	0.6	1.7	1
Amount attributable to parent	[1]	0.8	0.2	1.3	0.8
Net periodic benefit cost		2.1	0.8	3	1.8
OG&E [Member] | Postretirement Benefit Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		0	0	0.1	0.1
Interest cost		0.6	0.8	1.9	2.4
Expected return on plan assets		(0.4)	(0.4)	(1.3)	(1.2)
Amortization of net loss		0.6	0.5	2	1.6
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	[2]	(1.2)	(1.5)	(3.7)	(4.6)
Total net periodic benefit cost		(0.4)	(0.6)	(1)	(1.7)
Amount attributable to parent	[1]	(0.1)	(0.2)	(0.3)	(0.6)
Net periodic benefit cost		(0.5)	(0.8)	(1.3)	(2.3)
Capitalized portion of net periodic pension benefit cost		$ 0	$ 0	$ 0.1	$ 0.1
[1]	"Amount paid by unconsolidated affiliates" is only applicable to OGE Energy. "Amount allocated from OGE Energy" is only applicable to OG&E.
[2]	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.
[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]	Included in the Pension tracker, as presented in the regulatory assets and liabilities table in Note 1.

Report of Business Segments (De

Report of Business Segments (Details) - USD ($) $ in Millions		3 Months Ended						9 Months Ended
		Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020		Dec. 31, 2020
Segment Reporting Information [Line Items]
Operating revenues		$ 864.4			$ 702.1			$ 3,072.4	$ 1,636.9
Fuel, purchased power and direct transmission expense		330.1			209.1			1,876.9	481.5
Other operation and maintenance		115.4			109.7			343.9	347.2
Depreciation and amortization		108.6			100.5			310.2	292.2
Taxes other than income		25.5			24.8			78.5	76.3
OPERATING INCOME		284.8			258			462.9	439.7
Equity in earnings of unconsolidated affiliates	[1]	41.2			15.8			127.9	(703.8)	[2]
Other Nonoperating Income (Expense)		2.1			(0.8)			2.9	3.3
Interest expense		39.5			39.8			118.8	118.9
Income Tax Expense (Benefit)		36.1			55.8			56.8	(151.2)
Net income (loss)		252.5	$ 112.9	$ 52.7	177.4	$ 85.9	$ (491.8)	418.1	(228.5)
Investment in unconsolidated affiliates		478.9			376.8			478.9	376.8		$ 397.4
Total assets		12,177.5			10,497.6			12,177.5	10,497.6		$ 10,718.8
Asset Impairment Charges	[3]	0			0			0	780
Electric Utility [Member]
Segment Reporting Information [Line Items]
Operating revenues		864.4			702.1			3,072.4	1,636.9
Fuel, purchased power and direct transmission expense		330.1			209.1			1,876.9	481.5
Other operation and maintenance		115.8			110.1			344.4	348.8
Depreciation and amortization		108.6			100.5			310.2	292.2
Taxes other than income		24.6			23.9			75.3	72.8
OPERATING INCOME		285.3			258.5			465.6	441.6
Equity in earnings of unconsolidated affiliates		0			0			0	0	[2]
Other Nonoperating Income (Expense)		2.9			0.6			5.8	2.9
Interest expense		38			39.5			114.3	115.7
Income Tax Expense (Benefit)		26.4			20.1			37	30.5
Net income (loss)		223.8			199.5			320.1	298.3
Investment in unconsolidated affiliates		0			0			0	0
Total assets		11,597.9			10,323.3			11,597.9	10,323.3
Natural Gas Midstream Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues		0			0			0	0
Fuel, purchased power and direct transmission expense		0			0			0	0
Other operation and maintenance		0.3			0.3			2.3	1.2
Depreciation and amortization		0			0			0	0
Taxes other than income		0.1			0.2			0.3	0.4
OPERATING INCOME		(0.4)			(0.5)			(2.6)	(1.6)
Equity in earnings of unconsolidated affiliates		41.2			15.8			127.9	(703.8)	[2]
Other Nonoperating Income (Expense)		(0.5)			(0.7)			(1.2)	(0.7)
Interest expense		0			0			0	0
Income Tax Expense (Benefit)		9.5			4.5			23.2	(167.2)
Net income (loss)		30.8			10.1			100.9	(538.9)
Investment in unconsolidated affiliates		449.5			355.8			449.5	355.8
Total assets		451.8			358.7			451.8	358.7
Other Operations [Member]
Segment Reporting Information [Line Items]
Operating revenues		0			0			0	0
Fuel, purchased power and direct transmission expense		0			0			0	0
Other operation and maintenance		(0.7)			(0.7)			(2.8)	(2.8)
Depreciation and amortization		0			0			0	0
Taxes other than income		0.8			0.7			2.9	3.1
OPERATING INCOME		(0.1)			0			(0.1)	(0.3)
Equity in earnings of unconsolidated affiliates		0			0			0	0	[2]
Other Nonoperating Income (Expense)		(0.2)			(0.5)			(0.8)	2.5
Interest expense		1.6			0.5			5.4	4.6
Income Tax Expense (Benefit)		0.2			31.2			(3.4)	(14.5)
Net income (loss)		(2.1)			(32.2)			(2.9)	12.1
Investment in unconsolidated affiliates		29.4			21			29.4	21
Total assets		293.3			109.6			293.3	109.6
Eliminations [Member]
Segment Reporting Information [Line Items]
Operating revenues		0			0			0	0
Fuel, purchased power and direct transmission expense		0			0			0	0
Other operation and maintenance		0			0			0	0
Depreciation and amortization		0			0			0	0
Taxes other than income		0			0			0	0
OPERATING INCOME		0			0			0	0
Equity in earnings of unconsolidated affiliates		0			0			0	0	[2]
Other Nonoperating Income (Expense)		(0.1)			(0.2)			(0.9)	(1.4)
Interest expense		(0.1)			(0.2)			(0.9)	(1.4)
Income Tax Expense (Benefit)		0			0			0	0
Net income (loss)		0			0			0	0
Investment in unconsolidated affiliates		0			0			0	0
Total assets		$ (165.5)			$ (294)			$ (165.5)	$ (294)
[1]	For the three and nine months ended September 30, 2020, Enable recorded a $225.0 million impairment on its SESH equity method investment, which is included in their net loss for each period. 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 (loss) and was offset by basis differences that flow through the amortization of basis difference and dilution recognition line item above.
[2]	In 2020, OGE Energy recorded a $780.0 million impairment on its investment in Enable, as further discussed in Note 4
[3]	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 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 2020. Further discussion can be found in OGE Energy's 2020 Form 10-K .

Rate Matters and Regulation Rat

Rate Matters and Regulation Rate Matters and Regulation (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Estimated Refund to SPP	$ 13
Fuel clause under recoveries	98.2	$ 0
Plan Investments for Customers	28
Regulatory assets	1,264.9	415.6
Securitization Authorization Requested	760
Securitization Fuel Purchase Request	748.9
Securitization Fuel Cost Request Prudency	739.1
Grid Enhancement
Revenue Requirement	7
Minimum [Member]
Lost Revenues on Plant Investments for Customers	26
Maximum [Member]
Lost Revenues on Plant Investments for Customers	35.4
In Favor Cooperatives
Plan Investments for Customers	11.7
In Favor Cooperatives | Minimum [Member]
Lost Revenues on Plant Investments for Customers	2.5
In Favor Cooperatives | Maximum [Member]
Lost Revenues on Plant Investments for Customers	3.9
ARKANSAS
Public Utilities, Requested Rate Increase (Decrease), Amount	6.4
Public Utilities, Approved Rate Increase (Decrease), Amount	6.7
ARKANSAS | Extreme Cold Weather Costs
Regulatory assets	91	$ 0
Impact to Company [Member]
Estimated Refund to SPP	5
Customer Impact [Member]
Estimated Refund to SPP	$ 8