Derivatives and Hedge Accounting Activities (Fair Value of Derivatives) (Detail) - USD ($) $ in Millions		Mar. 31, 2020	Dec. 31, 2019
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	$ 91	$ 68
Derivative Asset, Noncurrent	[2]	59	25
Derivative Asset		150	93
Derivative Liabilities, Current		793	408	[3]
Derivative Liabilities, Noncurrent		853	332	[3]
Derivative Liabilities		1,646	740
Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[4]	14	20
Derivative Asset, Noncurrent	[5]	37	4
Derivative Asset		51	24
Derivative Liabilities, Current	[6]	481	243	[7]
Derivative Liabilities, Noncurrent	[8]	534	223
Derivative Liabilities		1,015	466
Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent	[9]		8
Derivative Asset			8
Derivative Liabilities, Current	[10]	69	33
Derivative Liabilities, Noncurrent	[11]	138	53
Derivative Liabilities		207	86
Commodity
Derivatives Fair Value [Line Items]
Derivative Asset, Current		80	67
Derivative Asset, Noncurrent		41	7
Derivative Liabilities, Current		45	83
Derivative Liabilities, Noncurrent		4	48
Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		14	20
Derivative Asset, Noncurrent		37	2
Derivative Liabilities, Current		23	58
Derivative Liabilities, Noncurrent		1	45
Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset, Current		11	1
Derivative Asset, Noncurrent		18	10
Derivative Liabilities, Current		747	322
Derivative Liabilities, Noncurrent		833	284
Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			2
Derivative Liabilities, Current		458	185
Derivative Liabilities, Noncurrent		533	178
Interest rate | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities, Current		68	30
Derivative Liabilities, Noncurrent		122	53
Foreign currency
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			8
Derivative Liabilities, Current		1	3
Derivative Liabilities, Noncurrent		16
Foreign currency | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			8
Derivative Liabilities, Current		1	3
Derivative Liabilities, Noncurrent		16
Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]		31
Derivative Asset, Noncurrent	[2]		19
Derivative Asset			50
Derivative Liabilities, Current		516	330
Derivative Liabilities, Noncurrent		738	268
Derivative Liabilities		1,254	598
Designated as Hedging Instrument | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent	[5]		2
Derivative Asset			2
Derivative Liabilities, Current		458	185
Derivative Liabilities, Noncurrent	[8]	533	178
Derivative Liabilities		991	363
Designated as Hedging Instrument | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent	[9]		8
Derivative Asset			8
Derivative Liabilities, Current	[10]	58	33
Derivative Liabilities, Noncurrent	[11]	135	53
Derivative Liabilities		193	86
Designated as Hedging Instrument | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset, Current			30
Derivative Asset, Noncurrent			1
Derivative Liabilities, Current			6
Derivative Liabilities, Noncurrent			1
Designated as Hedging Instrument | Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset, Current			1
Derivative Asset, Noncurrent			10
Derivative Liabilities, Current		515	321
Derivative Liabilities, Noncurrent		722	267
Designated as Hedging Instrument | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			2
Derivative Liabilities, Current		458	185
Derivative Liabilities, Noncurrent		533	178
Designated as Hedging Instrument | Interest rate | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities, Current		57	30
Derivative Liabilities, Noncurrent		119	53
Designated as Hedging Instrument | Foreign currency
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			8
Derivative Liabilities, Current		1	3
Derivative Liabilities, Noncurrent		16
Designated as Hedging Instrument | Foreign currency | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			8
Derivative Liabilities, Current		1	3
Derivative Liabilities, Noncurrent		16
Fair Value - Derivatives not under Hedge Accounting
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	91	37
Derivative Asset, Noncurrent	[2]	59	6
Derivative Asset		150	43
Derivative Liabilities, Current		277	78
Derivative Liabilities, Noncurrent		115	64
Derivative Liabilities		392	142
Fair Value - Derivatives not under Hedge Accounting | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[4]	14	20
Derivative Asset, Noncurrent	[5]	37	2
Derivative Asset		51	22
Derivative Liabilities, Current		23	58
Derivative Liabilities, Noncurrent	[8]	1	45
Derivative Liabilities		24	103
Fair Value - Derivatives not under Hedge Accounting | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities, Current	[10]	11
Derivative Liabilities, Noncurrent	[11]	3
Derivative Liabilities		14
Fair Value - Derivatives not under Hedge Accounting | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset, Current		80	37
Derivative Asset, Noncurrent		41	6
Derivative Liabilities, Current		45	77
Derivative Liabilities, Noncurrent		4	47
Fair Value - Derivatives not under Hedge Accounting | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		14	20
Derivative Asset, Noncurrent		37	2
Derivative Liabilities, Current		23	58
Derivative Liabilities, Noncurrent		1	45
Fair Value - Derivatives not under Hedge Accounting | Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset, Current		11
Derivative Asset, Noncurrent		18
Derivative Liabilities, Current		232	1
Derivative Liabilities, Noncurrent		111	$ 17
Fair Value - Derivatives not under Hedge Accounting | Interest rate | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities, Current		11
Derivative Liabilities, Noncurrent		$ 3

[1] Current derivative assets are presented in other current assets in Dominion Energy’s Consolidated Balance Sheets.

[2] Noncurrent derivative assets are presented in other deferred charges and other assets in Dominion Energy’s Consolidated Balance Sheets.

[3] Dominion Energy’s Consolidated Balance Sheet at December 31, 2019 has been derived from the audited Consolidated Balance Sheet at that date.

[4] Current derivative assets are presented in other current assets in Virginia Power’s Consolidated Balance Sheets.

[5] Noncurrent derivative assets are presented in other deferred charges and other assets in Virginia Power’s Consolidated Balance Sheets.

[6] See Note 19 for amounts attributable to affiliates.

[7] Virginia Power’s Consolidated Balance Sheet at December 31, 2019 has been derived from the audited Consolidated Balance Sheet at that date.

[8] Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in Virginia Power’s Consolidated Balance Sheets.

[9] Noncurrent derivatives assets are presented in other deferred charges and other assets in Dominion Energy Gas’ Consolidated Balance Sheets.

[10] Current derivative liabilities are presented in other current liabilities in Dominion Energy Gas’ Consolidated Balance Sheets.

[11] Noncurrent derivative liabilities are presented in other deferred credits and other liabilities in Dominion Energy Gas’ Consolidated Balance Sheets.