Operating Revenue (Schedule of Operating Revenue) (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		$ 3,084	$ 3,002	$ 6,924	$ 6,792
Other revenues	[1],[2]	(46)	104	(16)	252
GT&S Transaction
Public Utilities General Disclosures [Line Items]
Revenue associated with discontinued operations		1	1	2	3
NGL Midstream | Transferred at a Point in Time
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		8	4	15	11
Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		7	7	13	11
Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		25	39	47	75
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		1,723	1,765	3,530	3,674
Other revenues	[1],[3]	18	40	41	61
Virginia Electric and Power Company | Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		5	5	9	8
Virginia Electric and Power Company | Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		$ 18	$ 34	$ 38	$ 51

[1] Includes alternative revenue of $25 million and $39 million at Dominion Energy and $18 million and $34 million at Virginia Power for the three months ended June 30, 2021 and 2020, respectively, and $47 million and $75 million at Dominion Energy and $38 million and $51 million at Virginia Power for the six months ended June 30, 2021 and 2020, respectively.

[2] Includes revenue associated with services provided to discontinued operations of $1 million and $1 million for the three months ended June 30, 2021 and 2020, respectively, and $2 million and $3 million for the six months ended June 30, 2021 and 2020, respectively.

[3] See Note 19 for amounts attributable to affiliates.