Fair Value of Financial Assets and Liabilities - Impact of Derivative Activities on Income and Accumulated Other Comprehensive Loss (Details) - USD ($)		3 Months Ended
		Mar. 31, 2023	Mar. 31, 2022
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Derivative instruments designated as fair value hedges		$ 0	$ 0
Interest Rate Swap [Member]
Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract]
Derivative Liability, Notional Amount		0
Other Derivative Instruments
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		(75,000,000)
FTR settlement gains		(68,000,000)	(12,000,000)
Other Derivative Instruments | Electric Commodity
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		(75,000,000)	1,000,000
FTR settlement gains	[1]	$ 68,000,000	$ 12,000,000

[1] Recorded to electric fuel and purchased power. These derivative settlement gains and losses are shared with electric customers through fuel and purchased energy cost-recovery mechanisms, and reclassified out of income as regulatory assets or liabilities, as appropriate. FTR settlements are shared with customers and do not have a material impact on net income. Presented amounts reflect changes in fair value between auction and settlement dates, but exclude the original auction fair value.