Operating Segments - Virginia Power (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Gain (loss) on investments	$ (505)	$ 639	$ 412
Operating Segments
Segment Reporting Information [Line Items]
After- tax net expenses	(2,800)	(493)	(1,200)
Charge associated with storm damage and service restoration	125
Charge associated with storm damage and service restoration, after tax	93
Operating Segments | Nuclear Decommissioning Trust Fund
Segment Reporting Information [Line Items]
Gain (loss) on investments	559	568	335
Gain (loss) on investments, after tax	451	445	264
Operating Segments | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Asset early retirement expense			751
Asset early retirement expense after tax			559
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	117	68
Charge associated with storm damage and service restoration, after tax	87	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	243	61
Amortization of regulatory asset after tax	181	45
Charge for RGGI compliance cost	213
Charge for RGGI compliance cost, after tax	159
Charge in connection with comprehensive settlement agreement for fuel expenses	191
Charge in connection with comprehensive settlement agreement for fuel expenses, after-tax	142
Charges for Dismantling cost	167
Charges for Dismantling cost, after tax	124
Benefit for change in CCRO reserve		130
Benefit for change in CCRO reserve, after tax		97
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
Operating Segments | Virginia Electric and Power Company | Nuclear Decommissioning Trust Fund
Segment Reporting Information [Line Items]
Gain (loss) on investments	(78)
Gain (loss) on investments, after tax	(58)
Operating Segments | Corporate and Other
Segment Reporting Information [Line Items]
After- tax net expenses	(2,600)	(99)	(3,700)
After- tax net expenses for specific items	(2,500)	97	(3,400)
Operating Segments | Corporate and Other | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
After- tax net expenses	(792)	(202)	(863)
After- tax net expenses for specific items	$ (773)	$ (202)	$ (915)