Acquisitions and Dispositions (Schedule of Unaudited Pro Forma Information) (Detail) - Dominion Energy Questar Corporation - USD ($) $ / shares in Units, $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	[1]	Sep. 30, 2019	[1]	Sep. 30, 2018
Business Acquisition [Line Items]
Operating Revenue	$ 4,269	$ 4,356		$ 13,104		$ 12,902
Net income attributable to Dominion Energy	$ 1,029	$ 923		$ 1,991		$ 2,054
Earnings Per Common Share – Basic	$ 1.28	$ 1.23		$ 2.47		$ 2.74
Earnings Per Common Share – Diluted	$ 1.26	$ 1.23		$ 2.44		$ 2.74

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