Derivatives and Hedge Accounting Activities (Fair Value of Derivatives) (Detail) - USD ($) $ in Millions		Sep. 30, 2019	Dec. 31, 2018
Derivatives Fair Value [Line Items]
Derivative Asset		$ 93	$ 294
Derivative Liabilities		934	279
Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset		20	93
Derivative Liabilities		554	103
Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset		5	29
Derivative Liabilities		117	19
Current Assets
Derivatives Fair Value [Line Items]
Derivative Asset	[1]	73	223
Current Assets | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset	[2]	19	63
Current Assets | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset	[3]	2	3
Current Assets | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset		71	209
Current Assets | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset		19	60
Current Assets | Commodity | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset		2	3
Current Assets | Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset		2	14
Current Assets | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset			3
Noncurrent Assets
Derivatives Fair Value [Line Items]
Derivative Asset	[4]	20	71
Noncurrent Assets | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset	[5]	1	30
Noncurrent Assets | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset	[6]	3	26
Noncurrent Assets | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset		9	41
Noncurrent Assets | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset		1	30
Noncurrent Assets | Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset		8	4
Noncurrent Assets | Foreign currency
Derivatives Fair Value [Line Items]
Derivative Asset		3	26
Noncurrent Assets | Foreign currency | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset		3	26
Current Liabilities
Derivatives Fair Value [Line Items]
Derivative Liabilities	[7]	265	157
Current Liabilities | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities		165	25
Current Liabilities | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities	[8]	51	11
Current Liabilities | Commodity
Derivatives Fair Value [Line Items]
Derivative Liabilities		59	129
Current Liabilities | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities		16	15
Current Liabilities | Interest rate
Derivatives Fair Value [Line Items]
Derivative Liabilities		202	26
Current Liabilities | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities		149	10
Current Liabilities | Interest rate | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities		47	9
Current Liabilities | Foreign currency
Derivatives Fair Value [Line Items]
Derivative Liabilities		4	2
Current Liabilities | Foreign currency | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities		4	2
Noncurrent Liabilities
Derivatives Fair Value [Line Items]
Derivative Liabilities	[9]	669	122
Noncurrent Liabilities | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities	[10]	389	78
Noncurrent Liabilities | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities	[11]	66	8
Noncurrent Liabilities | Commodity
Derivatives Fair Value [Line Items]
Derivative Liabilities		21	6
Noncurrent Liabilities | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities		17
Noncurrent Liabilities | Interest rate
Derivatives Fair Value [Line Items]
Derivative Liabilities		648	116
Noncurrent Liabilities | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities		372	78
Noncurrent Liabilities | Interest rate | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities		66	8
Designated as Hedging Instrument
Derivatives Fair Value [Line Items]
Derivative Asset		33	105
Derivative Liabilities		842	166
Designated as Hedging Instrument | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset			3
Derivative Liabilities		521	88
Designated as Hedging Instrument | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset		5	29
Derivative Liabilities		117	19
Designated as Hedging Instrument | Current Assets
Derivatives Fair Value [Line Items]
Derivative Asset	[1]	20	69
Designated as Hedging Instrument | Current Assets | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset	[2]		3
Designated as Hedging Instrument | Current Assets | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset	[3]	2	3
Designated as Hedging Instrument | Current Assets | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset		18	55
Designated as Hedging Instrument | Current Assets | Commodity | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset		2	3
Designated as Hedging Instrument | Current Assets | Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset		2	14
Designated as Hedging Instrument | Current Assets | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset			3
Designated as Hedging Instrument | Noncurrent Assets
Derivatives Fair Value [Line Items]
Derivative Asset	[4]	13	36
Designated as Hedging Instrument | Noncurrent Assets | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset	[6]	3	26
Designated as Hedging Instrument | Noncurrent Assets | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset		2	6
Designated as Hedging Instrument | Noncurrent Assets | Interest rate
Derivatives Fair Value [Line Items]
Derivative Asset		8	4
Designated as Hedging Instrument | Noncurrent Assets | Foreign currency
Derivatives Fair Value [Line Items]
Derivative Asset		3	26
Designated as Hedging Instrument | Noncurrent Assets | Foreign currency | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Asset		3	26
Designated as Hedging Instrument | Current Liabilities
Derivatives Fair Value [Line Items]
Derivative Liabilities	[7]	213	45
Designated as Hedging Instrument | Current Liabilities | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities		149	10
Designated as Hedging Instrument | Current Liabilities | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities	[8]	51	11
Designated as Hedging Instrument | Current Liabilities | Commodity
Derivatives Fair Value [Line Items]
Derivative Liabilities		9	17
Designated as Hedging Instrument | Current Liabilities | Interest rate
Derivatives Fair Value [Line Items]
Derivative Liabilities		200	26
Designated as Hedging Instrument | Current Liabilities | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities		149	10
Designated as Hedging Instrument | Current Liabilities | Interest rate | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities		47	9
Designated as Hedging Instrument | Current Liabilities | Foreign currency
Derivatives Fair Value [Line Items]
Derivative Liabilities		4	2
Designated as Hedging Instrument | Current Liabilities | Foreign currency | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities		4	2
Designated as Hedging Instrument | Noncurrent Liabilities
Derivatives Fair Value [Line Items]
Derivative Liabilities	[9]	629	121
Designated as Hedging Instrument | Noncurrent Liabilities | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities	[10]	372	78
Designated as Hedging Instrument | Noncurrent Liabilities | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities	[11]	66	8
Designated as Hedging Instrument | Noncurrent Liabilities | Commodity
Derivatives Fair Value [Line Items]
Derivative Liabilities		2	5
Designated as Hedging Instrument | Noncurrent Liabilities | Interest rate
Derivatives Fair Value [Line Items]
Derivative Liabilities		627	116
Designated as Hedging Instrument | Noncurrent Liabilities | Interest rate | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities		372	78
Designated as Hedging Instrument | Noncurrent Liabilities | Interest rate | Dominion Energy Gas Holdings, LLC
Derivatives Fair Value [Line Items]
Derivative Liabilities		66	8
Fair Value - Derivatives not under Hedge Accounting
Derivatives Fair Value [Line Items]
Derivative Asset		60	189
Derivative Liabilities		92	113
Fair Value - Derivatives not under Hedge Accounting | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset		20	90
Derivative Liabilities		33	15
Fair Value - Derivatives not under Hedge Accounting | Current Assets
Derivatives Fair Value [Line Items]
Derivative Asset	[1]	53	154
Fair Value - Derivatives not under Hedge Accounting | Current Assets | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset	[2]	19	60
Fair Value - Derivatives not under Hedge Accounting | Current Assets | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset		53	154
Fair Value - Derivatives not under Hedge Accounting | Current Assets | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset		19	60
Fair Value - Derivatives not under Hedge Accounting | Noncurrent Assets
Derivatives Fair Value [Line Items]
Derivative Asset	[4]	7	35
Fair Value - Derivatives not under Hedge Accounting | Noncurrent Assets | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset	[5]	1	30
Fair Value - Derivatives not under Hedge Accounting | Noncurrent Assets | Commodity
Derivatives Fair Value [Line Items]
Derivative Asset		7	35
Fair Value - Derivatives not under Hedge Accounting | Noncurrent Assets | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Asset		1	30
Fair Value - Derivatives not under Hedge Accounting | Current Liabilities
Derivatives Fair Value [Line Items]
Derivative Liabilities	[7]	52	112
Fair Value - Derivatives not under Hedge Accounting | Current Liabilities | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities		16	15
Fair Value - Derivatives not under Hedge Accounting | Current Liabilities | Commodity
Derivatives Fair Value [Line Items]
Derivative Liabilities		50	112
Fair Value - Derivatives not under Hedge Accounting | Current Liabilities | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities		16	15
Fair Value - Derivatives not under Hedge Accounting | Current Liabilities | Interest rate
Derivatives Fair Value [Line Items]
Derivative Liabilities		2
Fair Value - Derivatives not under Hedge Accounting | Noncurrent Liabilities
Derivatives Fair Value [Line Items]
Derivative Liabilities	[9]	40	1
Fair Value - Derivatives not under Hedge Accounting | Noncurrent Liabilities | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities	[10]	17
Fair Value - Derivatives not under Hedge Accounting | Noncurrent Liabilities | Commodity
Derivatives Fair Value [Line Items]
Derivative Liabilities		19	$ 1
Fair Value - Derivatives not under Hedge Accounting | Noncurrent Liabilities | Commodity | Virginia Electric and Power Company
Derivatives Fair Value [Line Items]
Derivative Liabilities		17
Fair Value - Derivatives not under Hedge Accounting | Noncurrent Liabilities | Interest rate
Derivatives Fair Value [Line Items]
Derivative Liabilities		$ 21

[1] Current derivative assets include amounts presented in assets held for sale in Dominion Energy’s Consolidated Balance Sheets.

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

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

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

[7] Current derivative liabilities include $242 million and $157 million in other current liabilities at September 30, 2019 and December 31. 2018, respectively, with the remainder recorded in liabilities held for sale in Dominion Energy’s Consolidated Balance Sheets.

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

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

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

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