Operating Revenue (Schedule of Operating Revenue) (Parenthetical) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		$ 13,752	$ 13,745	$ 10,891
Other revenues	[1],[2]	420	656	308
Gas, Transmission & Storage
Public Utilities General Disclosures [Line Items]
Operating revenue		4	6	6
NGL Midstream | Transferred at a Point in Time
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		22	37	19
Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		20	24	17
Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		119	66	15
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		7,661	8,036	7,584
Other revenues	[1],[3]	102	72	35
Virginia Electric and Power Company | Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		11	17	11
Virginia Electric and Power Company | Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		$ 82	$ 52	$ 15

[1] Amounts above include alternative revenue of $119 million and $82 million for the year ended December 31, 2020 at Dominion Energy and Virginia Power, $66 million and $52 million for year ended December 31, 2019 at Dominion Energy and Virginia Power, respectively, and $15 million for year ended December 31, 2018 at both Dominion Energy and Virginia Power.

[2] Amounts above include revenue associated with services provided to entities presented in discontinued operations of $4 million for the year ended December 31, 2020 and $6 million for both years ended December 31, 2019 and 2018.

[3] See Notes 9 and 25 for amounts attributable to related parties and affiliates.