Variable Interest Entities - EEGH (Details) - USD ($) $ in Millions	1 Months Ended				3 Months Ended		9 Months Ended
	Nov. 30, 2020	Jul. 31, 2020	Dec. 31, 2019	Nov. 30, 2019	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
EEGH | Cove Point LNG, LP
Schedule of Equity Method Investments [Line Items]
Ownership interest							75.00%	25.00%
Percentage interest distributed		25.00%
EEGH | General Partner | Primary Beneficiary | Cove Point LNG, LP
Schedule of Equity Method Investments [Line Items]
Variable interest entity, ownership percentage							100.00%
EEGH | Limited Partner | Primary Beneficiary | Cove Point LNG, LP
Schedule of Equity Method Investments [Line Items]
Variable interest entity, ownership percentage							25.00%
EEGH | Not Discontinued Operations | GT&S Transaction | Cove Point LNG, LP
Schedule of Equity Method Investments [Line Items]
Percentage interest distributed	50.00%
EEGH | Cove Point LNG, LP | Dominion Energy, Inc.
Schedule of Equity Method Investments [Line Items]
Ownership interest				75.00%
EEGH | Cove Point LNG, LP | Not Discontinued Operations | GT&S Transaction
Schedule of Equity Method Investments [Line Items]
Percentage interest distributed	50.00%
EEGH | Carolina Gas Services, Inc. | Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Due to related parties					$ 31		$ 31		$ 22
EEGH | Carolina Gas Services, Inc. | Shared Services | Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Amounts of transaction					$ 3	$ 3	$ 9	$ 10
EEGH | Dominion Energy Questar Pipeline Services, Inc. | Shared Services | Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Amounts of transaction						7		21
EEGH | Dominion Energy Services, Inc. | Shared Services | Not Primary Beneficiary
Schedule of Equity Method Investments [Line Items]
Amounts of transaction						$ 22		$ 80
Dominion Energy, Inc. | Cove Point LNG, LP
Schedule of Equity Method Investments [Line Items]
Sold noncontrolling partner interest			25.00%