Operating Segments (Schedule of Segment Reporting Information, by Segment) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Operating revenue	[1]	$ 3,088	$ 2,813	$ 6,554	$ 6,197
Net income (loss) attributable to Dominion Energy		449	390	952	1,022
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue	[2]	1,829	1,747	3,577	3,578
Net income (loss) attributable to Dominion Energy		339	318	523	674
Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
Operating revenue	[3]	459	422	985	912
Net income (loss) attributable to Dominion Energy		15	77	181	185
Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		(187)	(333)	(376)	(759)
Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		3,088	2,813	6,554	6,197
Adjustments/Eliminations
Segment Reporting Information [Line Items]
Operating revenue		14	181	42	454
Net income (loss) attributable to Dominion Energy		0	0	0	0
Eliminations
Segment Reporting Information [Line Items]
Operating revenue		(173)	(152)	(334)	(305)
Power Delivery
Segment Reporting Information [Line Items]
Operating revenue		528	530	1,091	1,084
Net income (loss) attributable to Dominion Energy		145	127	301	252
Power Delivery | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		6	7	12	12
Power Delivery | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		534	537	1,103	1,096
Power Delivery | Operating Segments | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue		528	533	1,091	1,090
Net income (loss) attributable to Dominion Energy		145	125	299	250
Power Generation
Segment Reporting Information [Line Items]
Operating revenue		1,635	1,507	3,495	3,160
Net income (loss) attributable to Dominion Energy		276	240	624	501
Power Generation | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		3	2	5	5
Power Generation | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		1,638	1,509	3,500	3,165
Power Generation | Operating Segments | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue		1,301	1,214	2,701	2,488
Net income (loss) attributable to Dominion Energy		227	198	449	421
Gas Infrastructure
Segment Reporting Information [Line Items]
Operating revenue		914	589	2,136	1,490
Net income (loss) attributable to Dominion Energy		249	163	576	426
Gas Infrastructure | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		8	175	14	441
Gas Infrastructure | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		922	764	2,150	1,931
Gas Infrastructure | Operating Segments | Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
Operating revenue		459	422	985	912
Net income (loss) attributable to Dominion Energy		108	88	275	197
Corporate and Other
Segment Reporting Information [Line Items]
Operating revenue		(3)	6	(210)	9
Net income (loss) attributable to Dominion Energy		(221)	(140)	(549)	(157)
Corporate and Other | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		170	149	345	301
Corporate and Other | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		167	155	135	310
Corporate and Other | Operating Segments | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue			0	(215)	0
Net income (loss) attributable to Dominion Energy		(33)	(5)	(225)	3
Corporate and Other | Operating Segments | Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
Operating revenue		0	0	0	0
Net income (loss) attributable to Dominion Energy		$ (93)	$ (11)	$ (94)	$ (12)

[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.