Acquisitions and Dispositions (Schedule of Results of Operations of Disposal Groups Reported As Discontinued Operations) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income tax expense		$ 7	$ 31
Net income including noncontrolling interests	[1],[2]	28	229
Net income attributable to Dominion Energy		28	196
GT&S Transaction
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Operating revenue		1	2
Disposition Of G T S Operations To B H E | Q-Pipe Transaction
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Operating revenue		67	65
Operating Expense		19	33
Other income		0	1
Interest and related charges		5	4
Income before income taxes		43	29
Income tax expense		8	4
Net income including noncontrolling interests		35	25
Net income attributable to Dominion Energy		$ 35	25
Disposition Of G T S Operations To B H E | GT&S Transaction
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Operating revenue			563
Operating Expense			333
Other income			20
Interest and related charges			53
Income before income taxes			197
Income tax expense			27
Net income including noncontrolling interests			170
Noncontrolling interests			33
Net income attributable to Dominion Energy			$ 137

[1] Includes income tax expense of $7 million and $31 million for the three months ended March 31, 2021 and 2020, respectively.

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