Exit Activities and Discontinued Operations - Narrative (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended		30 Months Ended
	Oct. 01, 2021	Oct. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 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	5	0
Gain from divestiture of business related to post-closing adjustment			6
Post-closing purchase price adjustment						$ 36
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
Retention and severance costs					16
Cost deferred			$ 1	$ 2
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					8
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