Operating Revenue (Schedule of Operating Revenue) (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		$ 3,434	$ 3,536	$ 10,358	$ 10,350
Other revenues	[1],[2]	(258)	71	(274)	301
GT&S Transaction
Public Utilities General Disclosures [Line Items]
Revenue associated with discontinued operations		1	1	3	4
NGL Midstream | Transferred at a Point in Time
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		9	5	24	16
Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		16	21	29	32
Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		3	51	50	90
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		1,987	2,231	5,517	5,905
Other revenues	[1],[3]	(11)	17	30	78
Virginia Electric and Power Company | Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		13	16	22	24
Virginia Electric and Power Company | Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		$ 3	$ 12	$ 41	$ 63

[1] Includes alternative revenue of $3 million and $51 million at Dominion Energy and $3 million and $12 million at Virginia Power for the three months ended September 30, 2021 and 2020, respectively, and $50 million and $90 million at Dominion Energy and $41 million and $63 million at Virginia Power for the nine months ended September 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 September 30, 2021 and 2020, respectively, and $3 million and $4 million for the nine months ended September 30, 2021 and 2020, respectively.

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