Operating Segments (Schedule of Segment Reporting Information, by Segment) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Operating revenue	[1]	$ 3,451	$ 3,179	$ 10,005	$ 9,376
Net income (loss) attributable to Dominion Energy		854	665	1,806	1,687
Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue	[2]	2,232	2,154	5,809	5,732
Net income (loss) attributable to Dominion Energy		520	459	1,043	1,133
Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
Operating revenue	[3]	423	401	1,408	1,313
Net income (loss) attributable to Dominion Energy		136	117	317	302
Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		(175)	(361)	(551)	(1,120)
Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		3,451	3,179	10,005	9,376
Adjustments/Eliminations
Segment Reporting Information [Line Items]
Operating revenue		(2)	206	40	660
Net income (loss) attributable to Dominion Energy			0	0	0
Eliminations
Segment Reporting Information [Line Items]
Operating revenue		(177)	(155)	(511)	(460)
Power Delivery
Segment Reporting Information [Line Items]
Operating revenue		596	580	1,687	1,664
Net income (loss) attributable to Dominion Energy		163	138	464	390
Power Delivery | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		5	4	17	16
Power Delivery | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		601	584	1,704	1,680
Power Delivery | Operating Segments | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue		595	580	1,686	1,670
Net income (loss) attributable to Dominion Energy		163	137	462	387
Power Generation
Segment Reporting Information [Line Items]
Operating revenue		2,021	1,931	5,516	5,091
Net income (loss) attributable to Dominion Energy		414	369	1,038	870
Power Generation | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		3	3	8	8
Power Generation | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		2,024	1,934	5,524	5,099
Power Generation | Operating Segments | Virginia Electric and Power Company
Segment Reporting Information [Line Items]
Operating revenue		1,637	1,574	4,338	4,062
Net income (loss) attributable to Dominion Energy		347	314	796	735
Gas Infrastructure
Segment Reporting Information [Line Items]
Operating revenue		836	459	2,972	1,949
Net income (loss) attributable to Dominion Energy		264	187	840	613
Gas Infrastructure | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		7	204	21	645
Gas Infrastructure | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		843	663	2,993	2,594
Gas Infrastructure | Operating Segments | Dominion Energy Gas Holdings, LLC
Segment Reporting Information [Line Items]
Operating revenue		423	401	1,408	1,313
Net income (loss) attributable to Dominion Energy		146	121	421	318
Corporate and Other
Segment Reporting Information [Line Items]
Operating revenue			3	(210)	12
Net income (loss) attributable to Dominion Energy		13	(29)	(536)	(186)
Corporate and Other | Intersegment revenue
Segment Reporting Information [Line Items]
Operating revenue		160	150	505	451
Corporate and Other | Operating Segments
Segment Reporting Information [Line Items]
Operating revenue		160	153	295	463
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		10	8	(215)	11
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		$ (10)	$ (4)	$ (104)	$ (16)

[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.