Earnings Per Share (Calculation of Basic and Diluted EPS) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net income (loss)	$ (1,169)	$ 54	$ (1,439)	$ (626)
Preferred stock dividends (see Note 16)	(16)	0	(32)	0
Net income (loss) attributable to Dominion Energy – Basic	(1,185)	54	(1,471)	(626)
Dilutive effect of Series A Preferred Stock	0	(13)	0	0
Net income (loss) attributable to Dominion Energy - Diluted	$ (1,185)	$ 41	$ (1,471)	$ (626)
Average shares of common stock outstanding – Basic & Diluted	839.4	802.5	838.8	797.8
Net effect of dilutive securities	0.0	0.1	0.0	0.0
Average shares of common stock outstanding – Diluted	839.4	802.6	838.8	797.8
Earnings Per Common Share – Basic	$ (1.41)	$ 0.07	$ (1.75)	$ (0.78)
Earnings Per Common Share – Diluted	$ (1.41)	$ 0.05	$ (1.75)	$ (0.78)