Fair Value Measurements, Including Derivatives (Nonrecurring Fair Value Measurements) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment of assets and other charges		$ 4	$ 311	$ (14)
Nonutility Property
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Impairment of assets and other charges	$ 12
Impairment of assets and other charges, after-tax	9
Estimated fair value of property	$ 6