Operating Segments (Schedule of Segment Reporting Information, by Segment) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Operating Revenue		$ 3,176	$ 3,607	$ 10,084	$ 10,651
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interests	[1],[2]	65	19	119	(1,753)
Net income (loss) attributable to Dominion Energy		654	356	1,947	(1,083)
Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue		3,175	3,612	10,081	10,673
Adjustments & Eliminations
Segment Reporting Information [Line Items]
Operating Revenue		18	9	46	36
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interests		0	0	0	0
Net income (loss) attributable to Dominion Energy		0	0	0	0
Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue		1	(5)	3	(22)
Adjustments & Eliminations
Segment Reporting Information [Line Items]
Operating Revenue		(236)	(252)	(737)	(763)
Eliminations
Segment Reporting Information [Line Items]
Operating Revenue		(218)	(243)	(691)	(727)
Dominion Energy Virginia
Segment Reporting Information [Line Items]
Operating Revenue		2,330	2,254	6,062	6,003
Dominion Energy Virginia | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue		2,333	2,257	6,072	6,013
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interests		0	0	0	0
Net income (loss) attributable to Dominion Energy		599	613	1,464	1,479
Dominion Energy Virginia | Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue		(3)	(3)	(10)	(10)
Gas Distribution
Segment Reporting Information [Line Items]
Operating Revenue		373	314	1,804	1,606
Gas Distribution | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue		372	311	1,800	1,597
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interests		0	0	0	0
Net income (loss) attributable to Dominion Energy		69	64	415	375
Gas Distribution | Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue		1	3	4	9
Dominion Energy South Carolina
Segment Reporting Information [Line Items]
Operating Revenue		800	759	2,235	2,108
Dominion Energy South Carolina | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue		799	758	2,230	2,105
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interests		0	0	0	0
Net income (loss) attributable to Dominion Energy		151	157	337	326
Dominion Energy South Carolina | Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue		1	1	5	3
Contracted Assets
Segment Reporting Information [Line Items]
Operating Revenue		282	301	845	846
Contracted Assets | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue		265	288	790	810
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interests		0	51	0	153
Net income (loss) attributable to Dominion Energy		119	112	373	295
Contracted Assets | Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue		17	13	55	36
Corporate and Other
Segment Reporting Information [Line Items]
Operating Revenue		(391)	222	(171)	815
Corporate and Other | Operating Segments
Segment Reporting Information [Line Items]
Operating Revenue		(612)	(11)	(857)	112
Net Income (Loss) From Discontinued Operations Including Noncontrolling Interests		65	(32)	119	(1,906)
Net income (loss) attributable to Dominion Energy		(284)	(590)	(642)	(3,558)
Corporate and Other | Intersegment revenue
Segment Reporting Information [Line Items]
Operating Revenue		$ 221	$ 233	$ 686	$ 703

[1] Includes income tax expense (benefit) of $(6) million and $(10) million for the three months ended September 30, 2021 and 2020, respectively, and $5 million and $(572) million for the nine months ended September 30, 2021 and 2020, respectively.

[2] See Note 10 for amounts attributable to related parties.