Derivatives and Hedge Accounting Activities (Fair Value of Derivatives) (Detail) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	$ 209	$ 67
Derivative Asset, Noncurrent	[2]	447	330
Derivative Asset		656	397
Derivative Liabilities, Current	[3]	754	415
Derivative Liabilities, Current		729	412	[4]
Derivative Liabilities, Noncurrent	[5]	196	71
Derivative Liabilities		950	486
Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[6]	117	22
Derivative Asset, Noncurrent	[7]	242	159
Derivative Asset		359	181
Derivative Liabilities, Current	[8]	389	390	[9]
Derivative Liabilities, Noncurrent	[10]	64	15
Derivative Liabilities		453	405
Commodity contracts
Derivatives Fair Value [Line Items]
Derivative Asset, Current		190	58
Derivative Asset, Noncurrent		95	109
Derivative Liabilities, Current		484	42
Derivative Liabilities, Noncurrent		139	13
Commodity contracts | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		117	22
Derivative Asset, Noncurrent		72	93
Derivative Liabilities, Current		136	28
Derivative Liabilities, Noncurrent		35	1
Interest rate contracts
Derivatives Fair Value [Line Items]
Derivative Asset, Current		19	9
Derivative Asset, Noncurrent		352	221
Derivative Liabilities, Current		270	373
Derivative Liabilities, Noncurrent		57	58
Interest rate contracts | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent		170	66
Derivative Liabilities, Current		253	362
Derivative Liabilities, Noncurrent		29	14
Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	0	0
Derivative Asset, Noncurrent	[2]	170	66
Derivative Asset		170	66
Derivative Liabilities, Current	[3]	253	363
Derivative Liabilities, Noncurrent	[5]	29	19
Derivative Liabilities		282	382
Designated as Hedging Instrument | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[6]	0	0
Derivative Asset, Noncurrent	[7]	170	66
Derivative Asset		170	66
Derivative Liabilities, Current		253	362
Derivative Liabilities, Noncurrent	[10]	29	14
Derivative Liabilities		282	376
Designated as Hedging Instrument | Commodity contracts
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 | Commodity contracts | 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 contracts
Derivatives Fair Value [Line Items]
Derivative Asset, Current		0	0
Derivative Asset, Noncurrent		170	66
Derivative Liabilities, Current		253	363
Derivative Liabilities, Noncurrent		29	19
Designated as Hedging Instrument | Interest rate contracts | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent		170	66
Derivative Liabilities, Current		253	362
Derivative Liabilities, Noncurrent		29	14
Fair Value - Derivatives not under Hedge Accounting
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	209	67
Derivative Asset, Noncurrent	[2]	277	264
Derivative Asset		486	331
Derivative Liabilities, Current	[3]	501	52
Derivative Liabilities, Noncurrent	[5]	167	52
Derivative Liabilities		668	104
Fair Value - Derivatives not under Hedge Accounting | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[6]	117	22
Derivative Asset, Noncurrent	[7]	72	93
Derivative Asset		189	115
Derivative Liabilities, Current		136	28
Derivative Liabilities, Noncurrent	[10]	35	1
Derivative Liabilities		171	29
Fair Value - Derivatives not under Hedge Accounting | Commodity contracts
Derivatives Fair Value [Line Items]
Derivative Asset, Current		190	58
Derivative Asset, Noncurrent		95	109
Derivative Liabilities, Current		484	42
Derivative Liabilities, Noncurrent		139	13
Fair Value - Derivatives not under Hedge Accounting | Commodity contracts | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		117	22
Derivative Asset, Noncurrent		72	93
Derivative Liabilities, Current		136	28
Derivative Liabilities, Noncurrent		35	1
Fair Value - Derivatives not under Hedge Accounting | Interest rate contracts
Derivatives Fair Value [Line Items]
Derivative Asset, Current		19	9
Derivative Asset, Noncurrent		182	155
Derivative Liabilities, Current		17	10
Derivative Liabilities, Noncurrent		28	39
Fair Value - Derivatives not under Hedge Accounting | Interest rate contracts | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent		0	0
Derivative Liabilities, Current		0	0
Derivative Liabilities, Noncurrent		$ 0	$ 0

[1] Current derivative assets include $182 million and $63 million in other current assets in Dominion Energy’s Consolidated Balance Sheets as of September 30, 2021 and December 31, 2020, respectively.  The remainder is presented in current assets held for sale 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] Includes $25 million and $3 million at September 30, 2021 and December 31, 2020, respectively, presented in current liabilities held for sale in Dominion Energy’s Consolidated Balance Sheets.

[4] Dominion Energy’s Consolidated Balance Sheet at December 31, 2020 has been derived from the audited Consolidated Balance Sheet at that date.

[5] Noncurrent derivative liabilities are presented in other deferred credits and other liabilities 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, 2020 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.