Earnings Per Share (Calculation of Basic and Diluted EPS) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net Income (Loss) from continuing operations	$ 980	$ (466)
Preferred stock dividends (see Note 16)	(16)	(16)
Net income (loss) attributable to Dominion Energy from continuing operations – Basic	964	(482)
Net income (loss) attributable to Dominion Energy from continuing operations - Diluted	964	(482)
Net Income from discontinued operations	$ 28	$ 196
Average shares of common stock outstanding – Basic & Diluted	805.9	838.2
Average shares of common stock outstanding – Diluted	805.9	838.2
EPS from continuing operations – Basic	$ 1.19	$ (0.57)
EPS from discontinued operations – Basic	0.04	0.23
EPS attributable to Dominion Energy – Basic	1.23	(0.34)
EPS from continuing operations – Diluted	1.19	(0.57)
EPS from discontinued operations – Diluted	0.04	0.23
EPS attributable to Dominion Energy – Diluted	$ 1.23	$ (0.34)