Income Taxes (Schedule of Deferred Income Taxes) (Detail) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Deferred income taxes:
Total deferred income tax assets	$ 3,025	$ 3,285
Total deferred income tax liabilities	9,397	9,069
Total net deferred income tax liabilities	6,372	5,784
Plant and equipment, primarily depreciation method and basis differences	6,017	5,824
Excess deferred income taxes	(1,107)	(1,142)
Unrecovered NND Project costs	508	529
DESC rate refund	(113)	(140)
Toshiba Settlement	(189)	(204)
Nuclear decommissioning	1,114	991
Deferred state income taxes	857	702
Federal benefit of deferred state income taxes	(179)	(147)
Deferred fuel, purchased energy and gas costs	189
Deferred fuel, purchased energy and gas costs		(28)
Pension benefits	362	239
Other postretirement benefits	73	(14)
Loss and credit carryforwards	(1,571)	(1,534)
Valuation allowances	140	155
Partnership basis differences	398	593
Other	(127)	(40)
Total net deferred income tax liabilities	6,372	5,784
Deferred Investment Tax Credits – Regulated Operations	286	169
Total Deferred Taxes and Deferred Investment Tax Credits	6,658	5,953
Virginia Electric and Power Company
Deferred income taxes:
Total deferred income tax assets	1,373	1,204
Total deferred income tax liabilities	4,286	3,832
Total net deferred income tax liabilities	2,913	2,628
Plant and equipment, primarily depreciation method and basis differences	3,327	3,227
Excess deferred income taxes	(629)	(656)
Unrecovered NND Project costs	0	0
DESC rate refund	0	0
Toshiba Settlement	0	0
Nuclear decommissioning	324	303
Deferred state income taxes	420	305
Federal benefit of deferred state income taxes	(88)	(64)
Deferred fuel, purchased energy and gas costs	126
Deferred fuel, purchased energy and gas costs		(34)
Pension benefits	(119)	(105)
Other postretirement benefits	93	76
Loss and credit carryforwards	(537)	(354)
Valuation allowances	6	6
Partnership basis differences	0	0
Other	(10)	(76)
Total net deferred income tax liabilities	2,913	2,628
Deferred Investment Tax Credits – Regulated Operations	270	151
Total Deferred Taxes and Deferred Investment Tax Credits	$ 3,183	$ 2,779