Quarterly Financial and Common Stock Data (Unaudited) (Quarterly Financial and Common Stock Data) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Operating revenue	$ 3,361	$ 3,451	$ 3,088	$ 3,466	$ 3,210	$ 3,179	$ 2,813	$ 3,384	$ 13,366	[1]	$ 12,586	[1]	$ 11,737	[1]
Income (loss) from operations	834	1,150	742	875	953	1,152	753	1,079	3,601		3,937		3,448
Net income including noncontrolling interests	662	883	478	526	1,333	696	417	674	2,549		3,120		2,212
Net income	$ 641	$ 854	$ 449	$ 503	$ 1,312	$ 665	$ 390	$ 632	$ 2,447		$ 2,999		$ 2,123
Net income attributable to Dominion Energy - Basic	$ 0.97	$ 1.31	$ 0.69	$ 0.77	$ 2.04	$ 1.03	$ 0.62	$ 1.01	$ 3.74		$ 4.72		$ 3.44
Net income attributable to Dominion Energy - Diluted	0.97	1.30	0.69	0.77	2.04	1.03	0.62	1.01	3.74		4.72		3.44
Dividends declared per common share	$ 0.835	$ 0.835	$ 0.835	$ 0.835	$ 0.770	$ 0.770	$ 0.755	$ 0.755	$ 3.34		$ 3.035		$ 2.80
Virginia Electric and Power Company
Condensed Financial Statements, Captions [Line Items]
Operating revenue	$ 1,810	$ 2,232	$ 1,829	$ 1,748	$ 1,824	$ 2,154	$ 1,747	$ 1,831	$ 7,619	[2]	$ 7,556	[2]	$ 7,588	[2]
Income (loss) from operations	418	756	533	364	619	847	613	653	2,071		2,732		2,350
Net income	239	520	339	184	407	459	318	356	1,282		1,540		1,218
Dominion Energy Gas Holdings, LLC
Condensed Financial Statements, Captions [Line Items]
Operating revenue	532	423	459	526	501	401	422	490	1,940	[3]	1,814	[3]	1,638	[3]
Income (loss) from operations	(55)	182	7	201	181	185	116	156	335		638		593
Net income	$ (16)	$ 136	$ 15	$ 166	$ 313	$ 117	$ 77	$ 108	$ 301		$ 615		$ 392

[1] See Note 9 for amounts attributable to related parties.

[2] See Note 24 for amounts attributable to affiliates.

[3] See Note 24 for amounts attributable to related parties.