Derivatives - Schedule of Pretax Effect on Net Income of Derivatives Not Under Hedge Accounting, Including Realized and Unrealized Effects (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Total reversals of previously recognized unrealized (gain) loss on derivative instruments	$ 1,172	$ 1,565	$ 1,234
Total unrealized net gains (losses) from changes in fair value on derivative instruments	36	(1,111)	(3,494)
Net gain (loss) on derivative instruments	$ 1,208	$ 454	$ (2,260)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Operating revenues	Operating revenues	Operating revenues
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Total reversals of previously recognized unrealized (gain) loss on derivative instruments	$ (41)	$ (78)	$ 16
Total unrealized net gains (losses) from changes in fair value on derivative instruments	94	42	234
Operating revenues | Commodity Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total reversals of previously recognized unrealized (gain) loss on derivative instruments	1,140	1,472	1,940
Total unrealized net gains (losses) from changes in fair value on derivative instruments	(127)	(758)	(4,103)
Fuel, purchased power costs, and delivery fees/Depreciation and amortization | Commodity Contracts
Derivative Instruments, Gain (Loss) [Line Items]
Total reversals of previously recognized unrealized (gain) loss on derivative instruments	73	171	(722)
Total unrealized net gains (losses) from changes in fair value on derivative instruments	$ 69	$ (395)	$ 375