Investments (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2016	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Schedule Of Equity Method Investments [Line Items]
Contributions to equity method affiliates				$ 252	$ 76
Investment in equity method affiliates		$ 1,808		1,808		$ 1,561	[1]
Dominion Energy Gas Holdings, LLC
Schedule Of Equity Method Investments [Line Items]
Equity in earnings on investments		4	$ 3	11	9
Atlantic Coast Pipeline
Schedule Of Equity Method Investments [Line Items]
Contributions to equity method affiliates		85		202
Iroquois | Dominion Energy Gas Holdings, LLC | Partnership Interest
Schedule Of Equity Method Investments [Line Items]
Equity in earnings on investments				11	9
Distributions received from investment				11	$ 11
Investment in equity method affiliates		98		98		98
Carrying amount of investment that exceeded share of underlying equity		8		8		8
Percentage of non-controlling partnership interest sold	0.65%
Sales price of non-controlling partnership interest	$ 7
Amount of gain from sale	5
Amount of after tax gain from sale	$ 3
Categories of Investments, Marketable Securities, Trading Securities
Schedule Of Equity Method Investments [Line Items]
Rabbi trust securities		$ 111		$ 111		$ 104

[1] Dominion Energy’s Consolidated Balance Sheet at December 31, 2016 has been derived from the audited Consolidated Balance Sheet at that date.