Fair Value of Financial Assets and Liabilities - Impact of Derivative Activities on Income and Accumulated Other Comprehensive Loss (Details) - Other Derivative Instruments - Electric Commodity - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Changes in fair value of FTRs pre-tax gains	$ 13	$ 5	$ 80	$ 15
FTR settlement gains	$ 8	$ 4	$ 26	$ (13)