Operating Revenue (Schedule of Operating Revenue Recognition from Contracts with Customers) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Public Utilities General Disclosures [Line Items]
Operating Revenue	[1]	$ 3,451	$ 3,179	$ 10,005	$ 9,376
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating Revenue	[2]	2,232	2,154	5,809	5,732
Dominion Energy Gas Holdings, LLC
Public Utilities General Disclosures [Line Items]
Operating Revenue	[3]	423	$ 401	1,408	$ 1,313
Subsequent To Adoption of Revised Guidance
Public Utilities General Disclosures [Line Items]
Operating revenue		3,362		9,631
Nonregulated electric sales		322		1,022
Nonregulated gas sales		42		139
Nonregulated gas transportation and storage		162		286
Other regulated revenues		38		132
Other nonregulated revenues	[4],[5]	133		410
Operating Revenue		3,451		10,005
Subsequent To Adoption of Revised Guidance | FERC-regulated
Public Utilities General Disclosures [Line Items]
Regulated gas transportation and storage		266		800
Subsequent To Adoption of Revised Guidance | State-regulated
Public Utilities General Disclosures [Line Items]
Regulated gas transportation and storage		138		472
Subsequent To Adoption of Revised Guidance | Residential
Public Utilities General Disclosures [Line Items]
Regulated gas sales		73		553
Subsequent To Adoption of Revised Guidance | Commercial
Public Utilities General Disclosures [Line Items]
Regulated gas sales		15		152
Subsequent To Adoption of Revised Guidance | Other
Public Utilities General Disclosures [Line Items]
Regulated gas sales		3		14
Subsequent To Adoption of Revised Guidance | Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue		2,210		5,787
Other regulated revenues		30		95
Other nonregulated revenues	[4],[5]	10		41
Operating Revenue		2,232		5,809
Subsequent To Adoption of Revised Guidance | Dominion Energy Gas Holdings, LLC
Public Utilities General Disclosures [Line Items]
Operating revenue		423		1,407
Nonregulated gas sales	[5]	2		5
Other regulated revenues	[5]	4		16
Other nonregulated revenues	[5]	3		9
Operating Revenue		423		1,408
Management service revenue	[5]	50		157
Subsequent To Adoption of Revised Guidance | Dominion Energy Gas Holdings, LLC | FERC-regulated
Public Utilities General Disclosures [Line Items]
Regulated gas transportation and storage	[5]	179		561
Subsequent To Adoption of Revised Guidance | Dominion Energy Gas Holdings, LLC | State-regulated
Public Utilities General Disclosures [Line Items]
Regulated gas transportation and storage	[5]	131		450
Subsequent To Adoption of Revised Guidance | Dominion Energy Gas Holdings, LLC | Residential
Public Utilities General Disclosures [Line Items]
Regulated gas sales		12		54
Subsequent To Adoption of Revised Guidance | Dominion Energy Gas Holdings, LLC | Other
Public Utilities General Disclosures [Line Items]
Regulated gas sales		0		9
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Residential
Public Utilities General Disclosures [Line Items]
Operating revenue		1,036		2,641
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Commercial
Public Utilities General Disclosures [Line Items]
Operating revenue		737		1,897
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Industrial
Public Utilities General Disclosures [Line Items]
Operating revenue		143		371
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Government and Other Retail
Public Utilities General Disclosures [Line Items]
Operating revenue		224		647
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Wholesale
Public Utilities General Disclosures [Line Items]
Operating revenue		30		95
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Virginia Electric and Power Company | Residential
Public Utilities General Disclosures [Line Items]
Operating revenue		1,036		2,641
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Virginia Electric and Power Company | Commercial
Public Utilities General Disclosures [Line Items]
Operating revenue		737		1,897
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Virginia Electric and Power Company | Industrial
Public Utilities General Disclosures [Line Items]
Operating revenue		143		371
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Virginia Electric and Power Company | Government and Other Retail
Public Utilities General Disclosures [Line Items]
Operating revenue		224		647
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Virginia Electric and Power Company | Wholesale
Public Utilities General Disclosures [Line Items]
Operating revenue		30		95
Subsequent To Adoption of Revised Guidance | Other Revenues
Public Utilities General Disclosures [Line Items]
Operating revenue	[4]	89		374
Subsequent To Adoption of Revised Guidance | Other Revenues | Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue	[4],[5]	22		22
Subsequent To Adoption of Revised Guidance | Other Revenues | Dominion Energy Gas Holdings, LLC
Public Utilities General Disclosures [Line Items]
Operating revenue		0		1
Subsequent To Adoption of Revised Guidance | NGL Production | Dominion Energy Gas Holdings, LLC
Public Utilities General Disclosures [Line Items]
Operating revenue	[4],[5]	$ 42		$ 146

[1] See Note 10 for amounts attributable to related parties.

[2] See Note 18 for amounts attributable to affiliates.

[3] See Note 18 for amounts attributable to related parties.

[4] Amounts above include $108 million and $91 million for the three months ended September 30, 2018, and $170 million and $138 million for the nine months ended September 30, 2018 primarily consisting of NGL sales at Dominion Energy and Dominion Energy Gas, respectively, which are considered to be goods transferred at a point in time. In addition, the amounts include $10 million and $11 million of sales of renewable energy investment tax credits at both Dominion Energy and Virginia Power for the three and nine months ended September 30, 2018, respectively, which are considered to be goods transferred at a point in time.

[5] See Notes 10 and 18 for amounts attributable to related parties and affiliates.