Investments (Narrative) (Detail) - USD ($) $ in Millions				3 Months Ended
		May 05, 2022	Feb. 02, 2022	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Earnings from equity method investees				$ 80	$ 80
Net losses from discontinued operations including noncontrolling interest	[1]			(19)	(28)
Distributions received from investment				76	73
Equity method affiliates includes cash and accrued amounts of contributions				74	1,000
Equity method investment goodwill				11		$ 27
Income loss from continuing operations before income taxes extraordinary items noncontrolling interest				928	1,192
Liabilities from abandonment of project				217
Contributions to equity method affiliates				15	977
Assets				8,383		7,269	[2]
Liabilities				$ 10,581		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%
Initial fair value			$ 60
Dominion Energy Virginia | Held for sale
Schedule of Equity Method Investments [Line Items]
Assets				85
Liabilities				4
Dominion Energy Virginia | Subsequent Event
Schedule of Equity Method Investments [Line Items]
Percentage ownership in total units		50.00%
Total cash proceeds expected		$ 108
Expects to recognize gains totaling		130
Expects to recognize gains totaling, after tax		$ 100
Atlantic Coast Pipeline
Schedule of Equity Method Investments [Line Items]
Net losses from discontinued operations including noncontrolling interest				2	8
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				115		$ 113
Cove Point
Schedule of Equity Method Investments [Line Items]
Distributions received from investment				76	73
Income loss from continuing operations before income taxes extraordinary items noncontrolling interest				151	$ 138
Cove Point | Cove Point | GT&S Transaction
Schedule of Equity Method Investments [Line Items]
Percentage of noncontrolling limited partnership interest retained						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				231		$ 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				219		221
Trading Securities
Schedule of Equity Method Investments [Line Items]
Rabbi trust securities				$ 116		$ 122

[1] Includes income tax expense of $6 million and $7 million for the three months ended March 31, 2022 and 2021, respectively.

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