Earnings Per Share (Calculation of Basic and Diluted EPS) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income attributable to Dominion Energy	$ 854	$ 665	$ 1,806	$ 1,687
Average shares of common stock outstanding – Basic	653.9	642.5	652.4	633.4
Net effect of dilutive securities	1.0		0.4
Average shares of common stock outstanding – Diluted	654.9	642.5	652.8	633.4
Earnings Per Common Share – Basic	$ 1.31	$ 1.03	$ 2.77	$ 2.66
Earnings Per Common Share – Diluted	$ 1.30	$ 1.03	$ 2.77	$ 2.66