Exit Activities and Discontinued Operations (Narrative) (Details) - USD ($) $ in Millions		1 Months Ended		12 Months Ended			15 Months Ended	48 Months Ended
	Oct. 01, 2021	Mar. 31, 2022	Oct. 31, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Sep. 30, 2023	Sep. 30, 2023
Restructuring Cost and Reserve [Line Items]
Gain on sale				$ 0	$ 5	$ 657
Discontinued Operations, Held-for-sale | EnerBank
Restructuring Cost and Reserve [Line Items]
Proceeds from divestiture of businesses	$ 1,000
Gain on sale			$ 657		5	$ 657
Gain from divestiture of business related to post-closing adjustment		$ 6
Retention Benefits
Restructuring Cost and Reserve [Line Items]
Cost deferred				$ 16	24
Retention Benefits | D.E. Karn Generating Complex and J.H. Campbell Generating Units | Retention incentive program
Restructuring Cost and Reserve [Line Items]
Regulatory asset collection period				3 years
Retention Benefits | D.E. Karn Generating Complex
Restructuring Cost and Reserve [Line Items]
Aggregate cost incurred					$ 32
Retention and severance costs								$ 16
Retention Benefits | D.E. Karn Generating Complex | Retention incentive program
Restructuring Cost and Reserve [Line Items]
Cost deferred								12
Retention Benefits | D.E. Karn Generating Complex | Property, Plant and Equipment
Restructuring Cost and Reserve [Line Items]
Costs incurred and capitalized								$ 4
Retention Benefits | J.H. Campbell Generating Units
Restructuring Cost and Reserve [Line Items]
Expected cost				$ 50
Retention Benefits | J.H. Campbell Generating Units | Retention incentive program
Restructuring Cost and Reserve [Line Items]
Cost deferred							$ 35