Preferred Stock (Schedule of Equity Units) (Detail) - USD ($) shares in Millions, $ in Millions			1 Months Ended		12 Months Ended
		Jun. 14, 2019	Sep. 30, 2020	Aug. 31, 2019	Dec. 31, 2019	Dec. 31, 2020
Capital Unit [Line Items]
Units Issued			4.1	18.5	6.1
Total Preferred Stock					$ 2,387	$ 2,387
Stock Purchase Contract Liability					$ 212	$ 129
Preferred Stock
Capital Unit [Line Items]
Units Issued					2.0
Preferred Stock | 2019 Series A Corporate Units
Capital Unit [Line Items]
Units Issued		16.0
Total Net Proceeds	[1]	$ 1,582
Total Preferred Stock	[2]	$ 1,610
Cumulative Dividend Rate		1.75%
Stock Purchase Contract Annual Rate		5.50%
Stock Purchase Contract Liability	[3]	$ 250
Stock Purchase Contract Settlement Date		Jun. 01, 2022

[1] Issuance costs of $28 million were recorded as a reduction to preferred stock ($14 million) and common stock ($14 million) in the Consolidated Balance Sheets at December 31, 2019.

[2] Dominion Energy recorded dividends of $28 million ($17.50 per share) and $15 million ($9.479 per share) for the years ended December 31, 2020 and 2019, respectively.

[3] Payments of $83 million and $38 million were made in 2020 and 2019, respectively. The stock purchase contract liability was $129 million and $212 million at December 31, 2020 and 2019, respectively.