Derivative Instruments and Hedging Activities - Schedule of Derivative Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives, net of tax	$ (13)	$ 1	$ (1)	$ 8	$ 3	$ (3)
Interest rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives, net of tax	(57)			33			$ (33)	$ 34
Energy-Related Commodity Contracts - Operating Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives, net of tax	72			(22)			11	28
Energy-Related Commodity Contracts - Cost of Operation
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized gain (loss) on derivatives, net of tax	$ 0			$ 3			$ (3)	$ 3

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.