Income Taxes (Income Tax Expense for Continuing Operations Including Noncontrolling Interests) (Detail) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
	Nov. 30, 2020	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current:
Federal			$ (162)	$ (314)	$ (94)
State			45	(81)	58
Total current expense (benefit)			(117)	(395)	(36)
Deferred:
Taxes before operating loss carryforwards, investment tax credits and tax reform			151	12	168
Tax utilization expense of operating loss carryforwards			43	44	119
Investment tax credits			250	311	(51)
State			(19)	72	(50)
Total deferred expense (benefit)			425	439	186
Investment tax credit-gross deferral			121	42	62
Investment tax credit-amortization			(4)	(3)	(3)
Total income tax expense	$ 336	$ 173	425	83	209
Virginia Electric and Power Company
Current:
Federal			67	364	286
State			(13)	71	58
Total current expense (benefit)			54	435	344
Deferred:
Taxes before operating loss carryforwards, investment tax credits and tax reform			145	(226)	(128)
Tax utilization expense of operating loss carryforwards			0	0	0
Investment tax credits			(39)	(27)	(34)
State			118	7	22
Total deferred expense (benefit)			224	(246)	(140)
Investment tax credit-gross deferral			121	42	62
Investment tax credit-amortization			(2)	(2)	(2)
Total income tax expense			$ 397	$ 229	$ 264