Earnings Per Share (Calculation of Basic and Diluted EPS) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share [Abstract]
Net loss attributable to Dominion Energy	$ (270)	$ (680)
Preferred stock dividends (see Note 16)	(16)
Net loss attributable to Dominion Energy – Basic & Diluted	$ (286)	$ (680)
Average shares of common stock outstanding – Basic & Diluted	838.2	793.1
Earnings Per Common Share – Basic & Diluted	$ (0.34)	$ (0.86)