Fair Value of Financial Assets and Liabilities - Commodity Derivatives (Details) MWh in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2024 USD ($) MWh	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) MWh	Sep. 30, 2023 USD ($)	Dec. 31, 2023 MWh
Other Derivative Instruments
Derivative [Line Items]
Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)		$ (18)	$ 6	$ (26)	$ 78
Electric Commodity [Member]
Derivative [Line Items]
Mwh of electricity | MWh	[1]	11		11		8
cash flow hedge commodity
Derivative [Line Items]
Commodity contracts designated as cash flow hedges		$ 0		$ 0
Electric Commodity | Other Derivative Instruments
Derivative [Line Items]
Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)	[2]	$ (18)	$ 6	$ (26)	$ 78

[1] Not reflective of net positions in the underlying commodities.

[2] 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.