Operating Segments (Schedule of Segment Reporting Information, by Segment) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Operating revenue	[1]	$ 3,466	$ 3,384
Net income (loss) attributable to Dominion Energy		503	632
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue	[2]	1,748	1,831
Net income (loss) attributable to Dominion Energy		184	356
Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
Operating revenue	[3]	526	490
Net income (loss) attributable to Dominion Energy		166	108
Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		(189)	(426)
Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		3,466	3,384
Adjustments/Eliminations
Segment Reporting Information [Line Items]
Operating revenue		28	273
Net income (loss) attributable to Dominion Energy		0	0
Eliminations
Segment Reporting Information [Line Items]
Operating revenue		(161)	(153)
Power Delivery
Segment Reporting Information [Line Items]
Operating revenue		563	554
Net income (loss) attributable to Dominion Energy		156	125
Power Delivery | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		6	5
Power Delivery | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		569	559
Power Delivery | Operating Segments | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue		563	557
Net income (loss) attributable to Dominion Energy		154	125
Power Generation
Segment Reporting Information [Line Items]
Operating revenue		1,860	1,653
Net income (loss) attributable to Dominion Energy		348	261
Power Generation | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		2	3
Power Generation | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		1,862	1,656
Power Generation | Operating Segments | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue		1,400	1,274
Net income (loss) attributable to Dominion Energy		222	223
Gas Infrastructure
Segment Reporting Information [Line Items]
Operating revenue		1,222	901
Net income (loss) attributable to Dominion Energy		327	263
Gas Infrastructure | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		6	266
Gas Infrastructure | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		1,228	1,167
Gas Infrastructure | Operating Segments | Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
Operating revenue		526	490
Net income (loss) attributable to Dominion Energy		167	109
Corporate and Other
Segment Reporting Information [Line Items]
Operating revenue		(207)	3
Net income (loss) attributable to Dominion Energy		(328)	(17)
Corporate and Other | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		175	152
Corporate and Other | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		(32)	155
Corporate and Other | Operating Segments | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue		(215)
Net income (loss) attributable to Dominion Energy		(192)	8
Corporate and Other | Operating Segments | Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
Operating revenue		0	0
Net income (loss) attributable to Dominion Energy		$ (1)	$ (1)

[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.