Operating Segments - Virginia Power (Narrative) (Detail) - Operating Segments - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
After- tax net expenses	$ 493	$ 1,200	$ 1,900
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
After- tax net expenses	202	863
Benefit for change in expected CCRO reserve	130
Benefit for change in expected CCRO reserve, after tax	97
Charges associated with budget process related to customer arrears	77
Charges associated with budget process related to customer arrears, after tax	57
Charge associated with storm damage and service restoration	68
Charge associated with storm damage and service restoration, after tax	50
Loss from unbilled revenue reduction	151
Loss from unbilled revenue reduction, after tax	112
Net charge associated with settlement of the 2021 Triennial Review	125
Net charge associated with settlement of the 2021 Triennial Review, after tax	93
Amortization of regulatory asset	61
Amortization of regulatory asset after tax	45
Asset early retirement expense		751	346
Asset early retirement expense after tax		559	257
Charge for expected CCRO		130
Charge for expected CCRO, net of tax		97
Charges associated with legislation enacted related to customer arrears		127
Charges associated with legislation enacted related to customer arrears, net of tax		94
Charge related to a voluntary retirement program			198
Charge related to a voluntary retirement program, after-tax			146
Asset planned early retirement expense			160
Asset planned early retirement expense, after tax			119
Payment for contract termination			135
Payment for contract termination, after tax			100
Cancellation abandonment expense			62
Cancellation abandonment expense, after tax			46
Benefit from revision of future closure costs			113
Benefit from revision of future closure costs, after tax			84
Corporate and Other
Segment Reporting Information [Line Items]
After- tax net expenses	99	3,700	1,800
After- tax net expenses for specific items	(97)	3,400	1,500
Corporate and Other | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
After- tax net expenses	202	863	634
After- tax net expenses for specific items	$ 202	$ 915	$ 627