Investments (Narrative) (Detail) - USD ($) $ in Millions		1 Months Ended	3 Months Ended
		Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Earnings from equity method investees			$ 80	$ 80
Net losses from discontinued operations including noncontrolling interest	[1]		5	(19)
Distributions received from investment			85	76
Equity method affiliates includes cash and accrued amounts of contributions			10	74
Equity method investment goodwill			9		$ 9
Income loss from continuing operations before income taxes extraordinary items noncontrolling interest			1,223	928
Contributions to equity method affiliates			10	$ 15
Assets			9,605		9,850	[2]
Liabilities			$ 12,762		13,450	[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
Limited partnership interest sale transaction, proceeds received		$ 60		$ 60
Percentage ownership in total units		50.00%	50.00%	50.00%
Initial fair value		$ 60		$ 60
Atlantic Coast Pipeline
Schedule of Equity Method Investments [Line Items]
Net losses from discontinued operations including noncontrolling interest			$ 1	2
Contributions to equity method affiliates			6	0
Atlantic Coast Pipeline | Other Current Liabilities
Schedule of Equity Method Investments [Line Items]
Liabilities from abandonment of project			100		114
Cove Point
Schedule of Equity Method Investments [Line Items]
Distributions received from investment			$ 83	$ 76
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			$ 217		223
Equity method investment goodwill					(1)
Finite Lived Equity Method Investment Basis Difference | Cove Point
Schedule of Equity Method Investments [Line Items]
Equity method investment goodwill			213		215
Trading Securities
Schedule of Equity Method Investments [Line Items]
Rabbi trust securities			$ 108		$ 111

[1] Includes income tax expense (benefit) of $(1) million and $6 million for the three months ended three months ended March 31, 2023 and 2022, respectively.

[2] Dominion Energy’s Consolidated Balance Sheet at December 31, 2022 has been derived from the audited Consolidated Balance Sheet at that date.