Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period				$ 9,230
Accumulated other comprehensive loss at end of period		$ 9,353		9,353
Income Tax Expense (Benefit)		21	$ 31	21	$ 31
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period		(20)	(21)	(20)	(21)
Losses reclassified from net accumulated other comprehensive loss		0	0
Net current period other comprehensive loss		1	1	1	1
Accumulated other comprehensive loss at end of period		(19)	(20)	(19)	(20)
Gains and Losses on Cash Flow Hedges | Interest Rate Swap
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Losses reclassified from net accumulated other comprehensive loss	[1]	(1)	(1)	(1)	(1)
Defined Benefit and Postretirement Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period		(1)	(1)	(2)	(1)
Losses reclassified from net accumulated other comprehensive loss		1	0
Net current period other comprehensive loss		(1)	0	0	0
Accumulated other comprehensive loss at end of period		(2)	(1)	(2)	(1)
Defined Benefit and Postretirement Items | Interest Rate Swap
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Losses reclassified from net accumulated other comprehensive loss	[1]	0	0	0	0
Total
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period		(21)	(22)	(22)	(22)
Losses reclassified from net accumulated other comprehensive loss		1	0
Net current period other comprehensive loss		0	1	1	1
Accumulated other comprehensive loss at end of period		(21)	(21)	(21)	(21)
Total | Interest Rate Swap
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Losses reclassified from net accumulated other comprehensive loss	[1]	$ (1)	$ (1)	$ (1)	$ (1)

[1] Included in interest charges.