Exit Activities and Discontinued Operations - Narrative (Details) - USD ($) $ in Millions		1 Months Ended		3 Months Ended		9 Months Ended		36 Months Ended
	Oct. 01, 2021	Mar. 31, 2022	Oct. 31, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Dec. 31, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain from divestiture of business						$ 5	$ 0
Discontinued Operations, Held-for-sale | EnerBank
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses	$ 1,000
Gain from divestiture of business			$ 657	$ 0	$ (3)	5	(8)
Gain from divestiture of business related to post-closing adjustment		$ 6
Post-closing purchase price adjustment									$ 36
Retention Benefits
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost deferred				11	$ 2	14	5
Retention Benefits | D.E. Karn Generating Complex
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Expected cost				35		35		$ 35
Retention and severance costs								16
Costs incurred and capitalized						0	$ 1
Retention Benefits | D.E. Karn Generating Complex | Retention Incentive Program
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost deferred								11
Retention Benefits | D.E. Karn Generating Complex | Property, Plant and Equipment
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Costs incurred and capitalized								4
Retention Benefits | J.H. Campbell Generating Units
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Expected cost				$ 50		50		$ 50
Retention Benefits | J.H. Campbell Generating Units | Retention Incentive Program
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost deferred						10
Severance Benefits | J.H. Campbell Generating Units
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Retention and severance costs						$ 4