Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive loss at beginning of period				$ 8,444
Accumulated other comprehensive loss at end of period		$ 8,688		8,688
Income Tax Expense (Benefit)		(9)	$ 3	0	$ 14
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		(21)	(22)	(21)	(23)
Net current period other comprehensive loss		0	0	0	1
Accumulated other comprehensive loss at end of period		(21)	(22)	(21)	(22)
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]	0	0	0	(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)	(1)	(1)
Net current period other comprehensive loss		0	0	0	0
Accumulated other comprehensive loss at end of period		(1)	(1)	(1)	(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		(22)	(23)	(22)	(24)
Net current period other comprehensive loss		0	0	0	1
Accumulated other comprehensive loss at end of period		(22)	(23)	(22)	(23)
Total | 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	$ (1)

[1] Included in interest charges.