Derivatives - Schedule of Pre-tax Effect of Interest Rate and Energy Related Derivatives on Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Weather Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ 0	$ 0	$ 14	$ 0
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	16	(40)	29	(18)
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Natural gas revenues
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	0	(15)	0	(13)
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Cost of natural gas
Derivative Instruments, Gain (Loss) [Line Items]
Derivative instruments not designated as hedging instruments, gain (loss), net	$ 16	$ (25)	$ 29	$ (5)