Operating Revenue (Schedule of Operating Revenue Recognition from Contracts with Customers) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Public Utilities General Disclosures [Line Items]
Operating Revenue	[1]	$ 3,088	$ 2,813	$ 6,554	$ 6,197
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating Revenue	[2]	1,829	1,747	3,577	3,578
Dominion Energy Gas Holdings, LLC
Public Utilities General Disclosures [Line Items]
Operating Revenue	[3]	459	$ 422	985	$ 912
Subsequent To Adoption of Revised Guidance
Public Utilities General Disclosures [Line Items]
Operating revenue		2,945		6,269
Nonregulated electric sales		282		700
Nonregulated gas sales		9		97
Nonregulated gas transportation and storage		124		124
Other regulated revenues		44		94
Other nonregulated revenues	[4],[5]	141		277
Operating Revenue		3,088		6,554
Subsequent To Adoption of Revised Guidance | FERC-regulated
Public Utilities General Disclosures [Line Items]
Regulated gas transportation and storage		272		534
Subsequent To Adoption of Revised Guidance | State-regulated
Public Utilities General Disclosures [Line Items]
Regulated gas transportation and storage		144		334
Subsequent To Adoption of Revised Guidance | Residential
Public Utilities General Disclosures [Line Items]
Regulated gas sales		116		480
Subsequent To Adoption of Revised Guidance | Commercial
Public Utilities General Disclosures [Line Items]
Regulated gas sales		34		137
Subsequent To Adoption of Revised Guidance | Other
Public Utilities General Disclosures [Line Items]
Regulated gas sales		1		11
Subsequent To Adoption of Revised Guidance | Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue		1,829		3,577
Other regulated revenues		33		65
Other nonregulated revenues	[5]	18		31
Subsequent To Adoption of Revised Guidance | Dominion Energy Gas Holdings, LLC
Public Utilities General Disclosures [Line Items]
Operating revenue		456		984
Nonregulated gas sales	[5]	1		3
Other regulated revenues	[5]	4		12
Other nonregulated revenues	[5]	4		6
Operating Revenue		459		985
Management service revenue	[5]	60		107
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]	183		382
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]	139		319
Subsequent To Adoption of Revised Guidance | Dominion Energy Gas Holdings, LLC | Residential
Public Utilities General Disclosures [Line Items]
Regulated gas sales		13		42
Subsequent To Adoption of Revised Guidance | Dominion Energy Gas Holdings, LLC | Other
Public Utilities General Disclosures [Line Items]
Regulated gas sales		2		9
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Residential
Public Utilities General Disclosures [Line Items]
Operating revenue		788		1,605
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Commercial
Public Utilities General Disclosures [Line Items]
Operating revenue		636		1,160
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Industrial
Public Utilities General Disclosures [Line Items]
Operating revenue		121		228
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Government and Other Retail
Public Utilities General Disclosures [Line Items]
Operating revenue		210		423
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Wholesale
Public Utilities General Disclosures [Line Items]
Operating revenue		23		65
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Virginia Electric and Power Company | Residential
Public Utilities General Disclosures [Line Items]
Operating revenue		788		1,605
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Virginia Electric and Power Company | Commercial
Public Utilities General Disclosures [Line Items]
Operating revenue		636		1,160
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Virginia Electric and Power Company | Industrial
Public Utilities General Disclosures [Line Items]
Operating revenue		121		228
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		210		423
Subsequent To Adoption of Revised Guidance | Regulated Electric Sales | Virginia Electric and Power Company | Wholesale
Public Utilities General Disclosures [Line Items]
Operating revenue		23		65
Subsequent To Adoption of Revised Guidance | Other Revenues
Public Utilities General Disclosures [Line Items]
Operating revenue		143		285
Subsequent To Adoption of Revised Guidance | Other Revenues | Dominion Energy Gas Holdings, LLC
Public Utilities General Disclosures [Line Items]
Operating revenue	[5]	3		1
Subsequent To Adoption of Revised Guidance | NGL Production | Dominion Energy Gas Holdings, LLC
Public Utilities General Disclosures [Line Items]
Operating revenue	[4],[5]	$ 50		$ 104

[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 $33 million and $21 million for the three months ended June 30, 2018, and $63 million and $47 million for the six months ended June 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.

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