Derivatives and Hedge Accounting Activities (Fair Value of Derivatives) (Detail) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	$ 36	$ 67
Derivative Asset, Noncurrent	[2]	813	330
Derivative Asset		849	397
Derivative Liabilities, Current	[3]	221	415
Derivative Liabilities, Noncurrent	[4]	43	71
Derivative Liabilities		264	486
Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[5]	11	22
Derivative Asset, Noncurrent	[6]	348	159
Derivative Asset		359	181
Derivative Liabilities, Current	[7]	171	390	[8]
Derivative Liabilities, Noncurrent	[9]	7	15
Derivative Liabilities		178	405
Commodity
Derivatives Fair Value [Line Items]
Derivative Asset, Current		24	58
Derivative Asset, Noncurrent		85	109
Derivative Liabilities, Current		61	42
Derivative Liabilities, Noncurrent		17	13
Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		11	22
Derivative Asset, Noncurrent		65	93
Derivative Liabilities, Current		21	28
Derivative Liabilities, Noncurrent		7	1
Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset, Current		12	9
Derivative Asset, Noncurrent		728	221
Derivative Liabilities, Current		160	373
Derivative Liabilities, Noncurrent		26	58
Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent		283	66
Derivative Liabilities, Current		150	362
Derivative Liabilities, Noncurrent			14
Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	0	0
Derivative Asset, Noncurrent	[2]	287	66
Derivative Asset		287	66
Derivative Liabilities, Current	[3]	150	363
Derivative Liabilities, Noncurrent	[4]	0	19
Derivative Liabilities		150	382
Designated as Hedging Instrument | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[5]	0	0
Derivative Asset, Noncurrent	[6]	283	66
Derivative Asset		283	66
Derivative Liabilities, Current		150	362
Derivative Liabilities, Noncurrent	[9]	0	14
Derivative Liabilities		150	376
Designated as Hedging Instrument | Commodity
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 | 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	0
Derivative Asset, Noncurrent		287	66
Derivative Liabilities, Current		150	363
Derivative Liabilities, Noncurrent		0	19
Designated as Hedging Instrument | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent		283	66
Derivative Liabilities, Current		150	362
Derivative Liabilities, Noncurrent			14
Fair Value - Derivatives not under Hedge Accounting
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[1]	36	67
Derivative Asset, Noncurrent	[2]	526	264
Derivative Asset		562	331
Derivative Liabilities, Current	[3]	71	52
Derivative Liabilities, Noncurrent	[4]	43	52
Derivative Liabilities		114	104
Fair Value - Derivatives not under Hedge Accounting | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current	[5]	11	22
Derivative Asset, Noncurrent	[6]	65	93
Derivative Asset		76	115
Derivative Liabilities, Current		21	28
Derivative Liabilities, Noncurrent	[9]	7	1
Derivative Liabilities		28	29
Fair Value - Derivatives not under Hedge Accounting | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset, Current		24	58
Derivative Asset, Noncurrent		85	109
Derivative Liabilities, Current		61	42
Derivative Liabilities, Noncurrent		17	13
Fair Value - Derivatives not under Hedge Accounting | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Current		11	22
Derivative Asset, Noncurrent		65	93
Derivative Liabilities, Current		21	28
Derivative Liabilities, Noncurrent		7	1
Fair Value - Derivatives not under Hedge Accounting | Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset, Current		12	9
Derivative Asset, Noncurrent		441	155
Derivative Liabilities, Current		10	10
Derivative Liabilities, Noncurrent		26	39
Fair Value - Derivatives not under Hedge Accounting | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset, Noncurrent		0	0
Derivative Liabilities, Current		$ 0	0
Derivative Liabilities, Noncurrent			$ 0

[1] Current derivative assets include $31 million and $63 million in other current assets in Dominion Energy’s Consolidated Balance Sheets as of March 31, 2021 and December 31, 2020, respectively.  The remainder is recorded 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] Current derivative liabilities include $217 million and $412 million at March 31, 2021 and December 31, 2020, respectively, presented in other current liabilities in Dominion Energy’s Consolidated Balance Sheets. The remainder is in current liabilities held for sale in Dominion Energy’s Consolidated Balance Sheets.

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

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

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

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

[8] Virginia Power’s Consolidated Balance Sheet at December 31, 2020 has been derived from the audited Consolidated Balance Sheet at that date.

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