Operating Revenue (Schedule of Operating Revenue) (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		$ 3,840	$ 3,827
Other revenues	[1],[2]	30	111
GT&S Transaction
Public Utilities General Disclosures [Line Items]
Revenue associated with discontinued operations		1	2
NGL Midstream | Transferred at a Point in Time
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		7	7
Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		6	4
Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		22	36
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		1,807	1,909
Other revenues	[2],[3]	23	21
Virginia Electric and Power Company | Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		4	3
Virginia Electric and Power Company | Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		$ 20	$ 17

[1] Amounts above include revenue associated with services provided to discontinued operations of $1 million and $2 million for the three months ended March 31, 2021 and 2020, respectively.

[2] Amounts above include alternative revenue of $22 million and $36 million at Dominion Energy and $20 million and $17 million at Virginia Power for the three months ended March 31, 2021 and 2020, respectively.

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