Commodity and Other Derivative Contractual Assets and Liabilities - 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, 2023	Dec. 31, 2022	Dec. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss)	$ (1,111)	$ (3,494)	$ (383)
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Total revenues	Total revenues	Total revenues
Unrealized mark-to-market net (gains) losses on interest rate swaps	$ (36)	$ 250	$ 134
Interest rate swaps
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss)	42	234	81
Operating revenues
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized mark-to-market net (gains) losses on interest rate swaps	714	(2,163)	(1,191)
Operating revenues \| Commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss)	(758)	(4,103)	(1,196)
Fuel, purchased power costs and delivery fees
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized mark-to-market net (gains) losses on interest rate swaps	(224)	(347)	432
Fuel, purchased power costs and delivery fees \| Commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Net gain (loss)	$ (395)	$ 375	$ 732

Commodity and Other Derivative Contractual Assets and Liabilities - 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, 2023

Dec. 31, 2022

Dec. 31, 2021

Derivative Instruments, Gain (Loss) [Line Items]

Net gain (loss)

$ (1,111)

$ (3,494)

$ (383)

Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]

Total revenues

Unrealized mark-to-market net (gains) losses on interest rate swaps