Operating Segments - Dominion Energy (Narrative) (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Gain (loss) on investments	$ 228	$ (658)
Operating Segments
Segment Reporting Information [Line Items]
After- tax net benefits (expenses)	245	(1,900)
Operating Segments | Nuclear Decommissioning Trust Funds
Segment Reporting Information [Line Items]
Gain (loss) on investments	183	(691)
Gain (loss) on investments, after tax	142	(536)
Corporate and Other | Operating Segments
Segment Reporting Information [Line Items]
After- tax net benefits (expenses)	26	(1,000)
After- tax net benefits (expenses) for specific items	231	(1,000)
Contracted Energy | Operating Segments
Segment Reporting Information [Line Items]
Loss related to economic hedging activities		391
Loss related to economic hedging activities after tax		296
Gain related to economic hedging activities	335
Gain related to economic hedging activities after tax	255
Loss associated with sale of Kewaunee		649
Loss associated with sale of Kewaunee, after tax		513
Contracted Energy | Operating Segments | Nuclear Decommissioning Trust Funds
Segment Reporting Information [Line Items]
Gain (loss) on investments, after tax	124	(465)
Dominion Energy Virginia | Operating Segments
Segment Reporting Information [Line Items]
Charge associated with storm damage and service restoration		94
Charge associated with storm damage and service restoration, after tax		70
Charge for amortization of a regulatory asset, 2021 Triennial Review	183	183
Charge for amortization of a regulatory asset, 2021 Triennial Review, after tax	136	136
Charge in connection with comprehensive settlement agreement for fuel expenses		191
Charge in connection with comprehensive settlement agreement for fuel expenses, after-tax		142
Charge for RGGI compliance cost		213
Charge for RGGI compliance cost, after tax		159
Charges for Dismantling cost		60
Charges for Dismantling cost, after tax		45
Dominion Energy Virginia | Operating Segments | Nuclear Decommissioning Trust Funds
Segment Reporting Information [Line Items]
Gain (loss) on investments, after tax	18	$ (71)
Dominion Energy Virginia | Deferred amounts related to certain riders | Operating Segments
Segment Reporting Information [Line Items]
Charge for the write-off of certain previously deferred amounts	36
Charge for the write-off of certain previously deferred amounts, after tax	27
Dominion Energy South Carolina | Operating Segments
Segment Reporting Information [Line Items]
Benefit related to real estate transactions	31
Benefit related to real estate transactions, after tax	$ 23