Investments (Narrative) (Detail) - USD ($)		1 Months Ended		3 Months Ended			6 Months Ended
		May 31, 2022	Feb. 28, 2022	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Earnings from equity method investees				$ 83,000,000		$ 65,000,000	$ 163,000,000	$ 145,000,000
Net losses from discontinued operations including noncontrolling interest	[1]			1,000,000		(26,000,000)	(18,000,000)	(54,000,000)
Distributions received from investment							167,000,000	166,000,000
Equity method affiliates includes cash and accrued amounts of contributions							90,000,000	1,000,000,000.0
Equity method investment goodwill				11,000,000			11,000,000		$ 27,000,000
Income loss from continuing operations before income taxes extraordinary items noncontrolling interest				(569,000,000)		222,000,000	359,000,000	1,414,000,000
Liabilities from abandonment of project				225,000,000			225,000,000
Contributions to equity method affiliates							31,000,000	983,000,000
Assets				11,388,000,000			11,388,000,000		7,269,000,000	[2]
Liabilities				13,166,000,000			$ 13,166,000,000		8,673,000,000	[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							$ 85,000,000
Amount of gain from sale							11,000,000
Amount of gain from sale, after tax							8,000,000
Dominion Energy Virginia
Schedule of Equity Method Investments [Line Items]
Cash consideration from sale of noncontrolling interest			$ 120,000,000
Amount of gain from sale					$ 23,000,000
Amount of gain from sale, after tax					$ 16,000,000
Agreement entered date			2022-02
Limited partnership interest sale transaction, proceeds received			$ 60,000,000
Percentage ownership in total units		50.00%	50.00%
Initial fair value			$ 60,000,000
Total cash proceeds expected		$ 108,000,000
Expects to recognize gains totaling		130,000,000
Expects to recognize gains totaling, after tax		100,000,000
Dominion Energy Virginia | Held for sale
Schedule of Equity Method Investments [Line Items]
Assets				86,000,000			86,000,000
Liabilities				4,000,000			4,000,000
Atlantic Coast Pipeline
Schedule of Equity Method Investments [Line Items]
Net losses from discontinued operations including noncontrolling interest							4,000,000	22,000,000
Contributions to equity method affiliates							0	965,000,000
Atlantic Coast Pipeline | Other Current Liabilities
Schedule of Equity Method Investments [Line Items]
Liabilities from abandonment of project				117,000,000			117,000,000		113,000,000
Cove Point
Schedule of Equity Method Investments [Line Items]
Distributions received from investment				$ 85,000,000		$ 77,000,000	$ 161,000,000	$ 150,000,000
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				$ 158,000,000		$ 136,000,000	$ 309,000,000	$ 274,000,000
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				$ 237,000,000			$ 237,000,000		244,000,000
Equity method investment goodwill									(4,000,000)
Finite Lived Equity Method Investment Basis Difference | Cove Point
Schedule of Equity Method Investments [Line Items]
Equity method investment goodwill				218,000,000			218,000,000		221,000,000
Trading Securities
Schedule of Equity Method Investments [Line Items]
Rabbi trust securities				111,000,000			111,000,000		$ 122,000,000
2019 Series A Corporate Units
Schedule of Equity Method Investments [Line Items]
Short-term deposit		2,000,000,000.0
Allowances for credit losses recognized				$ 0			$ 0
2019 Series A Corporate Units | Minimum
Schedule of Equity Method Investments [Line Items]
Short-term deposit		1,600,000,000
2019 Series A Corporate Units | Maximum
Schedule of Equity Method Investments [Line Items]
Short-term deposit		2,000,000,000.0
2019 Series A Corporate Units | Series A Preferred Stock
Schedule of Equity Method Investments [Line Items]
Redemption obligation		$ 1,600,000,000
Preferred stock dividend rate percentage		1.75%

[1] Includes income tax expense (benefit) of $(2) million and $4 million for the three months ended June 30, 2022 and 2021, respectively, and $4 million and $11 million for the six months ended June 30, 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.