Acquisitions and Dispositions (Schedule of Unaudited Pro Forma Information) (Detail) - Dominion Energy Questar Corporation - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	[1]	Dec. 31, 2016	[2]
Business Acquisition [Line Items]
Operating Revenue	$ 17,505		$ 12,497
Net income attributable to Dominion Energy	$ 2,081		$ 2,300
Earnings Per Common Share - Basic	$ 2.78		$ 3.73
Earnings Per Common Share - Diluted	$ 2.77		$ 3.73

[1] Amounts include adjustments for non-recurring costs directly related to the SCANA Combination.

[2] Amounts include adjustments for non-recurring costs directly related to the Dominion Energy Questar Combination.