Operating Segments - Virginia Power (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Gain (loss) on investments	$ 294	$ 134
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Gain (loss) on investments	39	19
Operating Segments
Segment Reporting Information [Line Items]
After- tax net benefits (expenses)	124	304
Gain (loss) on investments	266	123
Gain (loss) on investments, after tax	$ 202	$ 90
Investment, Type [Extensible Enumeration]	Nuclear Decommissioning Trust Fund [Member]	Nuclear Decommissioning Trust Fund [Member]
Operating Segments | Corporate and Other
Segment Reporting Information [Line Items]
After- tax net benefits (expenses)	$ 48	$ 393
After- tax net benefits (expenses) for specific items	191	466
Operating Segments | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Charge for amortization of a regulatory asset, 2021 Triennial Review		61
Charge for amortization of a regulatory asset, 2021 Triennial Review, after tax		45
Gain (loss) on investments	37
Gain (loss) on investments, after tax	$ 27
Investment, Type [Extensible Enumeration]	Nuclear Decommissioning Trust Fund [Member]
Operating Segments | Virginia Electric and Power Company | Corporate and Other
Segment Reporting Information [Line Items]
After- tax net benefits (expenses)	$ 41	(31)
After- tax net benefits (expenses) for specific items	$ 39	$ (32)