Derivatives and Hedge Accounting Activities (Schedule of Derivatives not Designated as Hedging Instruments) (Detail) - Derivatives Not Designated as Hedging Instruments - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1]	$ (75)	$ (3)
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[2]	(65)	(9)
Dominion Energy Gas Holdings, LLC
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[3]	(8)
Commodity | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[2],[4]	(65)	(9)
Commodity | Operating Revenue
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1]	65	3
Commodity | Purchased Gas
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1]	(14)	3
Commodity | Electric Fuel and Other Energy-Related Purchases
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1]	(65)	$ (9)
Interest rate
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[1],[5]	(61)
Interest rate | Dominion Energy Gas Holdings, LLC
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivatives	[3]	$ (8)

[1] Includes derivative activity amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in Dominion Energy’s Consolidated Statements of Income.

[2] Includes derivative activity amortized out of regulatory assets/liabilities. Amounts deferred into regulatory assets/liabilities have no associated effect in Virginia Power’s Consolidated Statements of Income.

[3] Amounts recorded in Dominion Energy Gas’ Consolidated Statements of Income are classified in interest and related charges

[4] Amounts recorded in Virginia Power’s Consolidated Statements of Income are classified in electric fuel and other energy-related purchases.

[5] Amounts recorded in Dominion Energy’s Consolidated Statements of Income are classified in interest and related charges.