Other Comprehensive Income (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period		$ 9,230
Total income tax expense		29		$ 37		$ 33
Accumulated other comprehensive loss at end of period		9,742		9,230
Gains and Losses on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period		(20)		(21)
Amortization of net actuarial income (loss)		0
Net current period other comprehensive income (loss)		1		1
Accumulated other comprehensive loss at end of period		(19)		(20)		(21)
Other Comprehensive Income (Loss) before reclassifications		0		0
Gains and Losses on Cash Flow Hedges | Interest Rate Swap
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amortization of net actuarial income (loss)		(1)	[1]	(1)	[2]
Defined Benefit Pension and Postretirement Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period		(2)		(1)
Amortization of net actuarial income (loss)	[3]	(1)
Net current period other comprehensive income (loss)		1		(1)
Accumulated other comprehensive loss at end of period		(1)		(2)		(1)
Other Comprehensive Income (Loss) before reclassifications		0		(1)
Defined Benefit Pension and Postretirement Items | Interest Rate Swap
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amortization of net actuarial income (loss)		0		0
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period		(22)		(22)
Amortization of net actuarial income (loss)		(1)
Net current period other comprehensive income (loss)		2		0
Accumulated other comprehensive loss at end of period		(20)		(22)		$ (22)
Other Comprehensive Income (Loss) before reclassifications		0		(1)
Total | Interest Rate Swap
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amortization of net actuarial income (loss)		$ (1)		$ (1)

[1] Included in interest charges.

[2] Included in interest charges

[3] Included in the computation of net periodic pension and postretirement benefit costs. See Note 9 for further information.