Derivatives - Schedule of Pretax Effect on Net Income of Derivatives Not Under Hedge Accounting, Including Realized and Unrealized Effects (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized net gain (loss) from changes in fair value on derivative instruments:	$ 184	$ 376
Total unrealized net gain (loss) from change in fair value on derivative instruments	(799)	(505)
Net gain (loss) on derivative instruments	(615)	(129)
Interest Rate Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized net gain (loss) from changes in fair value on derivative instruments:	(5)	(11)
Total unrealized net gain (loss) from change in fair value on derivative instruments	(43)	58
Commodity contracts unrealized (gain) loss in operating revenues | Commodity Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized net gain (loss) from changes in fair value on derivative instruments:	212	261
Total unrealized net gain (loss) from change in fair value on derivative instruments	(725)	(608)
Commodity contracts unrealized gain (loss) in fuel, purchased power costs, and delivery fees | Commodity Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized net gain (loss) from changes in fair value on derivative instruments:	(23)	126
Total unrealized net gain (loss) from change in fair value on derivative instruments	$ (31)	$ 45