Acquisitions and Dispositions (Schedule of Results of Operations of Disposal Groups Reported As Discontinued Operations) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Income tax expense (benefit)		$ 188		$ (204)		$ 142
Net income (loss) including noncontrolling interests	[1],[2]	641		(1,878)		716
Net income (loss) attributable to Dominion Energy		641		(1,984)		705
GT&S Transaction
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Operating revenue		5		4		6
Income tax expense (benefit)		(17)
Disposition of GTS Operations | Q-Pipe Group
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Operating revenue		254	[3]	246		251
Operating expense	[4]	76	[3]	96		131
Other income (loss)	[5]	28	[3]	1		4
Interest and related charges	[6]	25	[3]	20		20
Income before income taxes		181	[3]	131		104
Income tax expense (benefit)	[7]	36	[3]	(9)		23
Net income (loss) including noncontrolling interests		145	[3]	140		81
Net income (loss) attributable to Dominion Energy		$ 145	[3]	140		81
Disposition of GTS Operations | GT&S Transaction
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Operating revenue				1,710	[3]	2,213
Operating expense	[4]			1,289	[3]	1,367
Other income (loss)	[5]			88	[3]	58
Interest and related charges	[6]			372	[3]	267
Income before income taxes				137	[3]	637
Income tax expense (benefit)	[7]			334	[3]	120
Net income (loss) including noncontrolling interests				(197)	[3]	517
Noncontrolling interests				106	[3]	11
Net income (loss) attributable to Dominion Energy				$ (303)	[3]	$ 506

[1] Includes income tax expense (benefit) of $188 million, $(204) million and $142 million for the years ended December 31, 2021, 2020 and 2019, respectively

[2] See Note 9 for amounts attributable to related parties

[3] Operations associated with the Q-Pipe Group are through the December 31, 2021 closing date. Operations associated with the GT&S Transaction are through the November 1, 2020 closing date.

[4] 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.

[5] Q-Pipe Group includes a $25 million benefit associated with the termination of the Q-Pipe Transaction in the third quarter of 2021.

[6] GT&S Transaction includes a loss of $237 million ($178 million after-tax) recorded in the third quarter of 2020 associated with cash flow hedges of debt-related items that were determined to be probable of not occurring.

[7] Excludes $17 million income tax benefit recorded in 2021 associated with the GT&S Transaction.