Derivatives and Hedge Accounting Activities (Gains and Losses on Derivatives in Cash Flow Hedging Relationships) (Detail) - Cash Flow Hedges - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	$ (320)	$ (145)	$ 40
Amount of Gain (Loss) Reclassified From AOCI to Income		(302)	83	(137)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	(332)	(255)	39
Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[3]	(37)	(30)	2
Amount of Gain (Loss) Reclassified From AOCI to Income		(2)	(1)	(1)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[4]	(338)	(259)	39
Commodity
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	0	125	64
Amount of Gain (Loss) Reclassified From AOCI to Income		23	143	(76)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	0	0
Commodity | Operating Revenue
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		25	142	(82)
Commodity | Purchased Gas
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		(4)	(3)
Commodity | Discontinued operations
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		2	4	(8)
Commodity | Electric Fuel and Other Energy-Related Purchases
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income				14
Foreign currency
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1],[5]	(11)	(18)	(6)
Amount of Gain (Loss) Reclassified From AOCI to Income	[5]	(6)	(6)	(13)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2],[5]	0	0	0
Interest rate
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[1]	(309)	(252)	(18)
Amount of Gain (Loss) Reclassified From AOCI to Income		(319)	(54)	(48)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[2]	(332)	(255)	39
Interest rate | Virginia Electric and Power Company
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives	[3],[6]	(37)	(30)	2
Amount of Gain (Loss) Reclassified From AOCI to Income	[6]	(2)	(1)	(1)
Increase (Decrease) in Derivatives Subject to Regulatory Treatment	[4],[6]	(338)	(259)	39
Interest rate | Discontinued operations
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		(236)	(5)	(5)
Interest rate | Interest and Related Charges
Derivative Instruments Gain Loss [Line Items]
Amount of Gain (Loss) Reclassified From AOCI to Income		$ (83)	$ (49)	$ (43)

[1] Amounts deferred into AOCI have no associated effect in Dominion Energy’s Consolidated Statements of Income.

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

[3] Amounts deferred into AOCI have no associated effect in Virginia Power’s Consolidated Statements of Income.

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

[5] Amounts recorded in Dominion Energy’s Consolidated Statements of Income are classified in discontinued operations.

[6] Amounts recorded in Virginia Power’s Consolidated Statements of Income are classified in interest and related charges.