Income Taxes (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Regulatory Liability, Noncurrent		$ 1,231.1	$ 1,188.9
Current Federal Tax Expense (Benefit)		16.4	8.4	$ (6.4)
Current State and Local Tax Expense (Benefit)		1.7	0.5	5.1
Current Income Tax Expense (Benefit)		18.1	8.9	(1.3)
Deferred Federal Income Tax Expense (Benefit)		133.1	(105.2)	48.5
Deferred State and Local Income Tax Expense (Benefit)		(10.0)	(31.1)	(17.4)
Deferred Income Tax Expense (Benefit)		123.1	(136.3)	31.1
Income Tax Expense (Benefit)		$ 141.2	$ (127.4)	$ 29.8
Statutory federal tax rate		21.00%	21.00%	21.00%
Federal renewable energy credit (A)	[1]	(2.00%)	(5.00%)	(6.00%)
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent	[2]	(1.10%)	0.00%	0.00%
Remeasurement of state deferred tax liabilities		(0.60%)	0.90%	(0.80%)
401(k) dividends		(0.20%)	(0.40%)	(0.40%)
State income taxes, net of federal income tax benefit		0.90%	(1.40%)	(1.20%)
Effective Income Tax Rate Reconciliation, Executive Compensation Limitation, Percent		0.10%	0.20%	0.20%
Amortization of net unfunded deferred taxes		(2.10%)	(4.40%)	(4.50%)
Other		0.00%	0.10%	(0.70%)
Effective income tax rate		16.10%	42.30%	6.40%
Accrued liabilities		$ (9.5)	$ (9.6)
Accrued vacation		(1.5)	(2.2)
Uncollectible accounts		(0.6)	(0.7)
Accelerated depreciation and other property related differences		1,677.3	1,721.2
Investment in Enable		0.0	302.6
Deferred Tax Liabilities, Investments		363.5	0.0
Regulatory assets		52.1	52.3
Income taxes recoverable from customers, net		(225.8)	(221.8)
Pension Plan		10.7	3.9
Bond redemption-unamortized costs		1.8	2.0
Derivative instruments		2.2	1.7
Federal tax credits		(208.4)	(236.6)
State tax credits		(221.2)	(204.4)
Postretirement medical and life insurance benefits		(19.2)	(22.4)
Net operating losses		(1.0)	(12.0)
Regulatory liabilities		(72.0)	(81.0)
Asset retirement obligations		(19.4)	(20.3)
Deferred federal investment tax credits		(3.1)	(2.7)
Other		7.4	(1.4)
Total deferred income tax liabilities, net		1,333.3	1,268.6
Unrecognized Tax Benefits		22.4	21.9	$ 20.7	$ 20.7
Current year additions		1.7	1.2	0.0
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions		(1.2)	0.0	$ 0.0
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued		0.0
Tax Credit Carryforward, Deferred Tax Asset		$ 208.4	$ 236.6
Stock-based compensation		0.10%	(0.30%)	(1.20%)
Effective Income Tax Rate Reconciliation, Tax Contingency, Percent	[3]	0.00%	31.60%	0.00%
Deferred Tax Asset [Member]
Unrecognized Tax Benefits		$ 18.1
State operating loss [Member]
Operating Loss Carryforwards		33.4
Deferred Tax Assets, Operating Loss Carryforwards, State and Local		1.0
Federal tax credits [Member]
Federal tax credits		(208.4)
Tax Credit Carryforward, Amount		208.4
Tax Credit Carryforward, Deferred Tax Asset		208.4
Oklahoma investment tax credits [Member]
State tax credits		(179.4)
Tax Credit Carryforward, Amount		227.1
Oklahoma capital investment board credits [Member]
State tax credits		(12.8)
Tax Credit Carryforward, Amount		12.8
Oklahoma zero emission tax credits [Member]
State tax credits		(28.9)
Tax Credit Carryforward, Amount		37.5
Louisiana inventory credits
State tax credits		(0.1)
Tax Credit Carryforward, Amount		0.1
Research and Development Credits [Member]
Tax Credit Carryforward, Amount		1.7	$ 1.2
Og and E [Member]
Regulatory Liability, Noncurrent		1,231.1	1,188.9
Current Federal Tax Expense (Benefit)		(9.0)	(3.8)	$ (7.9)
Current State and Local Tax Expense (Benefit)		9.0	(0.6)	4.1
Current Income Tax Expense (Benefit)		0.0	(4.4)	(3.8)
Deferred Federal Income Tax Expense (Benefit)		58.3	45.7	37.7
Deferred State and Local Income Tax Expense (Benefit)		(16.5)	(6.6)	(13.8)
Deferred Income Tax Expense (Benefit)		41.8	39.1	23.9
Income Tax Expense (Benefit)		$ 41.8	$ 34.7	$ 20.1
Statutory federal tax rate		21.00%	21.00%	21.00%
Federal renewable energy credit (A)	[1]	(4.40%)	(5.40%)	(7.60%)
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent	[2]	0.00%	0.00%	0.00%
Remeasurement of state deferred tax liabilities		0.00%	0.00%	0.00%
401(k) dividends		0.00%	0.00%	0.00%
State income taxes, net of federal income tax benefit		(1.40%)	(1.60%)	(1.80%)
Effective Income Tax Rate Reconciliation, Executive Compensation Limitation, Percent		0.00%	0.00%	0.00%
Amortization of net unfunded deferred taxes		(4.60%)	(4.80%)	(5.60%)
Other		(0.20%)	0.10%	(0.60%)
Effective income tax rate		10.40%	9.30%	5.40%
Accrued liabilities		$ (7.3)	$ (5.2)
Accrued vacation		(1.2)	(1.6)
Uncollectible accounts		(0.6)	(0.7)
Accelerated depreciation and other property related differences		1,677.3	1,721.2
Investment in Enable		0.0	0.0
Deferred Tax Liabilities, Investments		0.0	0.0
Regulatory assets		52.1	52.3
Income taxes recoverable from customers, net		(225.8)	(221.8)
Pension Plan		32.0	27.4
Bond redemption-unamortized costs		1.8	2.0
Derivative instruments		0.0	0.0
Federal tax credits		(209.8)	(236.6)
State tax credits		(205.9)	(189.0)
Postretirement medical and life insurance benefits		(13.0)	(15.3)
Net operating losses		0.0	(1.4)
Regulatory liabilities		(72.0)	(81.0)
Asset retirement obligations		(19.4)	(20.3)
Deferred federal investment tax credits		(3.1)	(2.7)
Other		(4.7)	(6.5)
Total deferred income tax liabilities, net		1,000.4	1,020.8
Unrecognized Tax Benefits		18.1	17.6	$ 16.4
Tax Credit Carryforward, Deferred Tax Asset		$ 209.8	$ 236.6
Stock-based compensation		0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Tax Contingency, Percent	[3]	0.00%	0.00%	0.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		$ (97.7)
Og and E [Member] | State operating loss [Member]
Operating Loss Carryforwards		0.0
Deferred Tax Assets, Operating Loss Carryforwards, State and Local		0.0
Og and E [Member] | Federal tax credits [Member]
Federal tax credits		(209.8)
Tax Credit Carryforward, Amount		209.8
Tax Credit Carryforward, Deferred Tax Asset		209.8
Og and E [Member] | Oklahoma investment tax credits [Member]
State tax credits		(164.2)
Tax Credit Carryforward, Amount		207.8
Og and E [Member] | Oklahoma capital investment board credits [Member]
State tax credits		(12.8)
Tax Credit Carryforward, Amount		12.8
Og and E [Member] | Oklahoma zero emission tax credits [Member]
State tax credits		(28.9)
Tax Credit Carryforward, Amount		37.5
Og and E [Member] | Louisiana inventory credits
State tax credits		0.0
Tax Credit Carryforward, Amount		0.0
OGE Energy [Member]
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		$ 6.6

[1] Represents credits primarily associated with the production from OG&E's wind farms.

[2] In connection with the Enable and Energy Transfer merger, the state income tax rates are expected to decrease, as Energy Transfer operates in significantly more states with generally lower tax rates than the historic Enable operating area.

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