Investments (Narrative) (Detail) - USD ($) $ in Millions		1 Months Ended		3 Months Ended				9 Months Ended
		May 31, 2022	Feb. 28, 2022	Sep. 30, 2022	Aug. 31, 2022	Mar. 31, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Earnings from equity method investees				$ 92			$ 69	$ 255	$ 214
Net losses from discontinued operations including noncontrolling interest	[1]			3			(65)	(15)	(119)
Distributions received from investment								268	263
Equity method affiliates includes cash and accrued amounts of contributions								93	1,000
Equity method investment goodwill				11				11		$ 27
Income loss from continuing operations before income taxes extraordinary items noncontrolling interest				905			636	1,264	2,050
Contributions to equity method affiliates								34	1,006
Assets				8,699				8,699		7,269	[2]
Liabilities				12,172				$ 12,172		8,673	[2]
Wrangler Retail Gas Holdings LLC | Gas Supply, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest percentage of limited partner interests								15.00%
Cash consideration from sale of noncontrolling interest								$ 85
Amount of gain from sale								11
Amount of gain from sale, after tax								8
Dominion Energy Virginia
Schedule of Equity Method Investments [Line Items]
Cash consideration from sale of noncontrolling interest			$ 120
Amount of gain from sale						$ 23
Amount of gain from sale, after tax						$ 16
Agreement entered date			2022-02
Limited partnership interest sale transaction, proceeds received			$ 60
Percentage ownership in total units		50.00%	50.00%
Initial fair value			$ 60
Total cash proceeds expected		$ 108
Expects to recognize gains totaling		130
Expects to recognize gains totaling, after tax		100
Dominion Energy Virginia | Held for sale
Schedule of Equity Method Investments [Line Items]
Assets				83				83
Liabilities				4				4
Atlantic Coast Pipeline
Schedule of Equity Method Investments [Line Items]
Net losses from discontinued operations including noncontrolling interest								6	19
Contributions to equity method affiliates								0	965
Atlantic Coast Pipeline | Other Current Liabilities
Schedule of Equity Method Investments [Line Items]
Liabilities from abandonment of project				119				119		113
Cove Point
Schedule of Equity Method Investments [Line Items]
Distributions received from investment				$ 98			$ 85	$ 259	$ 235
Percentage of Income loss from continuing operations before income taxes extraordinary items noncontrolling interest				100.00%			100.00%	100.00%	100.00%
Income loss from continuing operations before income taxes extraordinary items noncontrolling interest				$ 197			$ 136	$ 506	$ 410
Cove Point | Cove Point | GT&S Transaction
Schedule of Equity Method Investments [Line Items]
Percentage of noncontrolling limited partnership interest retained				50.00%				50.00%
Finite Lived Equity Method Investment Basis Difference
Schedule of Equity Method Investments [Line Items]
Carrying amount of investment that exceeded share of underlying equity				$ 227				$ 227		244
Equity method investment goodwill										(4)
Finite Lived Equity Method Investment Basis Difference | Cove Point
Schedule of Equity Method Investments [Line Items]
Equity method investment goodwill				216				216		221
Trading Securities
Schedule of Equity Method Investments [Line Items]
Rabbi trust securities				$ 109				$ 109		$ 122
2019 Series A Corporate Units
Schedule of Equity Method Investments [Line Items]
Short-term deposit		2,000
2019 Series A Corporate Units | Minimum
Schedule of Equity Method Investments [Line Items]
Short-term deposit		1,600
2019 Series A Corporate Units | Maximum
Schedule of Equity Method Investments [Line Items]
Short-term deposit		2,000
2019 Series A Corporate Units | Series A Preferred Stock
Schedule of Equity Method Investments [Line Items]
Redemption obligation		$ 1,600
Preferred stock dividend rate percentage		1.75%			1.75%

[1] Includes income tax expense (benefit) of $(6) million for the three months ended September 30, 2021 and $4 million and $5 million for the nine months ended September 30, 2022 and 2021, respectively. There were no such amounts recorded during the three months ended September 30, 2022.

[2] Dominion Energy’s Consolidated Balance Sheet at December 31, 2021 has been derived from the audited Consolidated Balance Sheet at that date.