Operating Revenue (Schedule of Operating Revenue Recognition from Contracts with Customers) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Regulated gas transportation and storage:
Total operating revenue	[1]	$ 3,466	$ 3,384
Subsequent To Adoption of Revised Guidance
Regulated electric sales:
Nonregulated electric sales		418
Regulated gas sales:
Nonregulated gas sales		88
Regulated gas transportation and storage:
Other regulated revenues		50
Other nonregulated revenues	[2],[3]	136
Total operating revenue from contracts with customers		3,324
Other revenues		142
Total operating revenue		3,466
Subsequent To Adoption of Revised Guidance | FERC-regulated
Regulated gas transportation and storage:
Regulated gas transportation and storage		262
Subsequent To Adoption of Revised Guidance | State-regulated
Regulated gas transportation and storage:
Regulated gas transportation and storage		190
Subsequent To Adoption of Revised Guidance | Residential
Regulated electric sales:
Regulated electric sales		817
Regulated gas sales:
Regulated gas sales		364
Subsequent To Adoption of Revised Guidance | Commercial
Regulated electric sales:
Regulated electric sales		524
Regulated gas sales:
Regulated gas sales		103
Subsequent To Adoption of Revised Guidance | Industrial
Regulated electric sales:
Regulated electric sales		107
Subsequent To Adoption of Revised Guidance | Government and Other Retail
Regulated electric sales:
Regulated electric sales		213
Subsequent To Adoption of Revised Guidance | Wholesale
Regulated electric sales:
Regulated electric sales		42
Subsequent To Adoption of Revised Guidance | Other
Regulated gas sales:
Regulated gas sales		10
Virginia Electric and Power Company
Regulated gas transportation and storage:
Total operating revenue	[4]	1,748	1,831
Virginia Electric and Power Company | Subsequent To Adoption of Revised Guidance
Regulated gas transportation and storage:
Other regulated revenues		32
Other nonregulated revenues	[3]	13
Total operating revenue from contracts with customers		1,748
Virginia Electric and Power Company | Subsequent To Adoption of Revised Guidance | Residential
Regulated electric sales:
Regulated electric sales		817
Virginia Electric and Power Company | Subsequent To Adoption of Revised Guidance | Commercial
Regulated electric sales:
Regulated electric sales		524
Virginia Electric and Power Company | Subsequent To Adoption of Revised Guidance | Industrial
Regulated electric sales:
Regulated electric sales		107
Virginia Electric and Power Company | Subsequent To Adoption of Revised Guidance | Government and Other Retail
Regulated electric sales:
Regulated electric sales		213
Virginia Electric and Power Company | Subsequent To Adoption of Revised Guidance | Wholesale
Regulated electric sales:
Regulated electric sales		42
Dominion Energy Gas Holdings, LLC
Regulated gas transportation and storage:
Total operating revenue	[5]	526	$ 490
Dominion Energy Gas Holdings, LLC | Subsequent To Adoption of Revised Guidance
Regulated gas sales:
Nonregulated gas sales	[3]	2
Regulated gas transportation and storage:
NGL revenue	[2],[3]	54
Management service revenue	[3]	47
Other regulated revenues	[3]	8
Other nonregulated revenues	[3]	2
Total operating revenue from contracts with customers		528
Other revenues	[3]	(2)
Total operating revenue		526
Dominion Energy Gas Holdings, LLC | Subsequent To Adoption of Revised Guidance | FERC-regulated
Regulated gas transportation and storage:
Regulated gas transportation and storage	[3]	199
Dominion Energy Gas Holdings, LLC | Subsequent To Adoption of Revised Guidance | State-regulated
Regulated gas transportation and storage:
Regulated gas transportation and storage	[3]	180
Dominion Energy Gas Holdings, LLC | Subsequent To Adoption of Revised Guidance | Residential
Regulated gas sales:
Regulated gas sales		29
Dominion Energy Gas Holdings, LLC | Subsequent To Adoption of Revised Guidance | Other
Regulated gas sales:
Regulated gas sales		$ 7

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

[2] Amounts above include $30 million and $26 million of NGL sales at Dominion Energy and Dominion Energy Gas, respectively, which are considered to be goods transferred at a point in time.

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

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

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