Operating Revenue (Schedule of Operating Revenue) (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Public Utilities General Disclosures [Line Items]
Other revenues	[1]	$ 173	$ 227
NGL Midstream | Transferred at a Point in Time
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		39	48
Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		4	3
Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		36	14
Dominion Energy Gas Holdings, LLC
Public Utilities General Disclosures [Line Items]
Other revenues		1	1
Dominion Energy Gas Holdings, LLC | NGL Midstream | Transferred at a Point in Time
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		1	1
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Other revenues	[1],[2]	21	14
Virginia Electric and Power Company | Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		3	1
Virginia Electric and Power Company | Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		$ 17	$ 8

[1] Includes alternative revenue. For the three months ended March 31, 2020 and 2019, such amounts included $36 million and $14 million, respectively, at Dominion Energy and $17 million and $8 million, respectively, at Virginia Power.

[2] See Notes 10 and 19 for amounts attributable to related parties and affiliates.