Earnings Per Share (Calculation of Basic and Diluted EPS) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Income from continuing operations										$ 1,583	$ 653	$ 2,087
Preferred stock dividends (see Note 19)										(65)	(17)
Net income attributable to Dominion Energy from continuing operations - Basic										1,518	636	2,087
Dilutive effect of Series A Preferred Stock										(11)	(28)
Net income attributable to Dominion Energy from continuing operations - Diluted										1,507	608	2,087
Net Income (Loss) from discontinued operations										$ (1,984)	$ 705	$ 360
Average shares of common stock outstanding – Basic										831.0	808.8	654.2
Net effect of dilutive securities	[1]										0.1	0.7
Average shares of common stock outstanding – Diluted										831.0	808.9	654.9
EPS from continuing operations - Basic		$ 0.98	$ 0.42	$ 1.01	$ (0.57)	$ 0.99	$ 1.14	$ (0.25)	$ (1.14)	$ 1.83	$ 0.79	$ 3.19
EPS from discontinued operations - Basic		(0.16)	(0.01)	(2.42)	0.23	0.22	0.05	0.32	0.28	(2.39)	0.87	0.55
EPS attributable to Dominion Energy - Basic		0.82	0.41	(1.41)	(0.34)	1.21	1.19	0.07	(0.86)	(0.56)	1.66	3.74
EPS from continuing operations - Diluted		0.98	0.42	0.90	(0.57)	0.99	1.12	(0.25)	(1.14)	1.82	0.75	3.19
EPS from discontinued operations - Diluted		(0.16)	(0.01)	(2.42)	0.23	0.22	0.05	0.32	0.28	(2.39)	0.87	0.55
EPS attributable to Dominion Energy - Diluted		$ 0.82	$ 0.41	$ (1.52)	$ (0.34)	$ 1.21	$ 1.17	$ 0.07	$ (0.86)	$ (0.57)	$ 1.62	$ 3.74

[1] Dilutive securities for 2018 consist primarily of forward sale agreements, effective April 2018 to December 2018. See Note 20 for more information.