Operating Segments - Virginia Power (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Segment Reporting Information [Line Items]
Gain (loss) on investments			$ 395	$ 308
Charge for the write-off of certain previously deferred amounts	$ 67	$ 37	97	135
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Gain (loss) on investments			52	45
Operating Segments
Segment Reporting Information [Line Items]
After- tax net benefits (expenses)			74	370
Gain (loss) on investments			350	281
Gain (loss) on investments, after tax			$ 271	$ 208
Investment, Type [Extensible Enumeration]	Nuclear Decommissioning Trust Fund [Member]	Nuclear Decommissioning Trust Fund [Member]	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)			$ (34)	$ 559
After- tax net benefits (expenses) for specific items			200	739
Operating Segments | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Charge for amortization of a regulatory asset, 2021 Triennial Review				122
Charge for amortization of a regulatory asset, 2021 Triennial Review, after tax				91
Gain (loss) on investments			46	41
Gain (loss) on investments, after tax			$ 35	30
Charge for the write-off of certain previously deferred amounts				36
Charge for the write-off of certain previously deferred amounts, after tax				27
Investment, Type [Extensible Enumeration]	Nuclear Decommissioning Trust Fund [Member]		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)			$ 35	(91)
After- tax net benefits (expenses) for specific items			$ 35	$ (87)