Fair Value of Financial Assets and Liabilities - Commodity Derivatives (Details) MWh in Millions, $ in Millions		3 Months Ended
		Mar. 31, 2025 USD ($) MWh	Mar. 31, 2024 USD ($)	Dec. 31, 2024 MWh
Other Derivative Instruments
Derivative [Line Items]
Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities)		$ (11)	$ 8
Electric Commodity [Member]
Derivative [Line Items]
Mwh of electricity | MWh	[1]	9		7
cash flow hedge commodity
Derivative [Line Items]
Commodity contracts designated as cash flow hedges		$ 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]	$ (11)	$ 8

[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.