Acquisitions and Dispositions (Schedule of Results of Operations of Disposal Groups Reported As Discontinued Operations) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income tax expense (benefit)		$ 4	$ (593)	$ 11	$ (562)
Net income (loss) including noncontrolling interests	[1],[2]	26	(2,001)	54	(1,772)
Net income (loss) attributable to Dominion Energy		26	(2,032)	54	(1,836)
GT&S Transaction
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Operating revenue		1	1	2	3
Disposition of GTS Operations | Q-Pipe Group
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Operating revenue		59	58	126	123
Operating expense	[3]	9	29	28	62
Other income		1	1	1	2
Interest and related charges		5	6	10	10
Income (loss) before income taxes		46	24	89	53
Income tax expense (benefit)		9	10	17	14
Net income (loss) including noncontrolling interests		37	14	72	39
Net income (loss) attributable to Dominion Energy		$ 37	14	$ 72	39
Disposition of GTS Operations | GT&S Transaction
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Operating revenue			480		1,043
Operating expense	[3]		770		1,103
Other income			12		32
Interest and related charges			46		99
Income (loss) before income taxes			(324)		(127)
Income tax expense (benefit)			(78)		(51)
Net income (loss) including noncontrolling interests			(246)		(76)
Noncontrolling interests			32		65
Net income (loss) attributable to Dominion Energy			$ (278)		$ (141)

[1] Includes income tax expense (benefit) of $4 million and $(593) million for the three months ended June 30, 2021 and 2020, respectively, and $11 million and $(562) million for the six months ended June 30, 2021 and 2020, respectively.

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

[3] GT&S Transaction includes a charge of $482 million ($359 million after-tax) recorded in the second quarter of 2020 associated with the probable abandonment of a significant portion of the Supply Header Project, as well as the establishment of a $75 million ARO as a result of the cancellation of the Atlantic Coast Pipeline Project.