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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Earnings Per Share [Abstract]
Net Income (Loss) from continuing operations	$ 369	$ 937	$ 767	$ (171)
Preferred stock dividends (see Note 16)	(16)	(7)	(48)	(8)
Net income (loss) attributable to Dominion Energy from continuing operations – Basic	353	930	719	(179)
Dilutive effect of Series A Preferred Stock		(13)	(28)
Net income (loss) attributable to Dominion Energy from continuing operations - Diluted	353	917	691	(179)
Net Income (Loss) from discontinued operations	$ (13)	$ 38	$ (1,850)	$ 520
Average shares of common stock outstanding – Basic & Diluted	833.8	813.0	837.1	802.9
Average shares of common stock outstanding – Diluted	833.8	813.0	837.1	802.9
EPS from continuing operations – Basic	$ 0.42	$ 1.14	$ 0.86	$ (0.22)
EPS from discontinued operations – Basic	(0.01)	0.05	(2.21)	0.64
EPS attributable to Dominion Energy – Basic	0.41	1.19	(1.35)	0.42
EPS from continuing operations – Diluted	0.42	1.12	0.83	(0.22)
EPS from discontinued operations – Diluted	(0.01)	0.05	(2.21)	0.64
EPS attributable to Dominion Energy – Diluted	$ 0.41	$ 1.17	$ (1.38)	$ 0.42