Derivatives and Hedge Accounting Activities (Fair Value of Derivatives) (Detail) - USD ($) $ in Millions		Sep. 30, 2020	Dec. 31, 2019
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	$ 98	$ 68
Derivative Asset, Noncurrent	[2]	154	25
Derivative Asset		252	93
Derivative Liabilities, Current		223	394	[3]
Derivative Liabilities, Current	[4]	239	408
Derivative Liabilities, Noncurrent		537	329	[3]
Derivative Liabilities, Noncurrent	[5]	537	332
Derivative Liabilities		776	740
Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[6]	48	20
Derivative Asset, Noncurrent	[7]	97	4
Derivative Asset		145	24
Derivative Liabilities, Current	[8]	15	243	[9]
Derivative Liabilities, Noncurrent	[10]	476	223
Derivative Liabilities		491	466
Commodity
Derivatives Fair Value [Line Items]
Derivative Asset, Current		80	67
Derivative Asset, Noncurrent		106	7
Derivative Liabilities, Current		41	83
Derivative Liabilities, Noncurrent		10	48
Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		48	20
Derivative Asset, Noncurrent		97	2
Derivative Liabilities, Current		15	58
Derivative Liabilities, Noncurrent		1	45
Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset, Current		12	1
Derivative Asset, Noncurrent		48	10
Derivative Liabilities, Current		194	322
Derivative Liabilities, Noncurrent		527	284
Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			2
Derivative Liabilities, Current			185
Derivative Liabilities, Noncurrent		475	178
Foreign currency
Derivatives Fair Value [Line Items]
Derivative Asset, Current		6
Derivative Asset, Noncurrent			8
Derivative Liabilities, Current		4	3
Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	0	31
Derivative Asset, Noncurrent	[2]	0	19
Derivative Asset		0	50
Derivative Liabilities, Current	[4]	0	330
Derivative Liabilities, Noncurrent	[5]	482	268
Derivative Liabilities		482	598
Designated as Hedging Instrument | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[6]	0	0
Derivative Asset, Noncurrent	[7]	0	2
Derivative Asset		0	2
Derivative Liabilities, Current		0	185
Derivative Liabilities, Noncurrent	[10]	475	178
Derivative Liabilities		475	363
Designated as Hedging Instrument | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset, Current		0	30
Derivative Asset, Noncurrent		0	1
Derivative Liabilities, Current		0	6
Derivative Liabilities, Noncurrent		0	1
Designated as Hedging Instrument | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		0	0
Derivative Asset, Noncurrent		0	0
Derivative Liabilities, Current		0	0
Derivative Liabilities, Noncurrent		0	0
Designated as Hedging Instrument | Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset, Current		0	1
Derivative Asset, Noncurrent		0	10
Derivative Liabilities, Current		0	321
Derivative Liabilities, Noncurrent		482	267
Designated as Hedging Instrument | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			2
Derivative Liabilities, Current			185
Derivative Liabilities, Noncurrent		475	178
Designated as Hedging Instrument | Foreign currency
Derivatives Fair Value [Line Items]
Derivative Asset, Current		0
Derivative Asset, Noncurrent			8
Derivative Liabilities, Current		0	3
Fair Value - Derivatives not under Hedge Accounting
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	98	37
Derivative Asset, Noncurrent	[2]	154	6
Derivative Asset		252	43
Derivative Liabilities, Current	[4]	239	78
Derivative Liabilities, Noncurrent	[5]	55	64
Derivative Liabilities		294	142
Fair Value - Derivatives not under Hedge Accounting | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[6]	48	20
Derivative Asset, Noncurrent	[7]	97	2
Derivative Asset		145	22
Derivative Liabilities, Current		15	58
Derivative Liabilities, Noncurrent	[10]	1	45
Derivative Liabilities		16	103
Fair Value - Derivatives not under Hedge Accounting | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset, Current		80	37
Derivative Asset, Noncurrent		106	6
Derivative Liabilities, Current		41	77
Derivative Liabilities, Noncurrent		10	47
Fair Value - Derivatives not under Hedge Accounting | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		48	20
Derivative Asset, Noncurrent		97	2
Derivative Liabilities, Current		15	58
Derivative Liabilities, Noncurrent		1	45
Fair Value - Derivatives not under Hedge Accounting | Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset, Current		12	0
Derivative Asset, Noncurrent		48	0
Derivative Liabilities, Current		194	1
Derivative Liabilities, Noncurrent		45	17
Fair Value - Derivatives not under Hedge Accounting | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent			0
Derivative Liabilities, Current			0
Derivative Liabilities, Noncurrent		0	0
Fair Value - Derivatives not under Hedge Accounting | Foreign currency
Derivatives Fair Value [Line Items]
Derivative Asset, Current		6
Derivative Asset, Noncurrent			0
Derivative Liabilities, Current		$ 4	$ 0

[1] Current derivative assets include $87 million and $61 million in other current assets in Dominion Energy’s Consolidated Balance Sheets as of September 30, 2020 and December 31, 2019, respectively.  The remainder is recorded in current assets held for sale in Dominion Energy’s Consolidated Balance Sheets.

[2] Noncurrent derivative assets include $154 million and $16 million in other deferred charges and other assets in Dominion Energy’s Consolidated Balance Sheets as of September 30, 2020 and December 31, 2019, respectively.  The remainder is recorded in noncurrent assets held for sale 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 liabilities include $16 million and $14 million at September 30, 2020 and December 31, 2019, respectively, presented in held for sale in Dominion Energy’s Consolidated Balance Sheets.

[5] Noncurrent derivative liabilities include $3 million at December 31, 2019 presented in held for sale in Dominion Energy’s Consolidated Balance Sheets.

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

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

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

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

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