Operating Revenue (Schedule of Operating Revenue) (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		$ 3,536	$ 3,623	$ 10,350	$ 9,993
Other revenues	[1],[2]	71	159	301	513
Gas, Transmission & Storage
Public Utilities General Disclosures [Line Items]
Revenue associated with discontinued operations		1		4
NGL Midstream | Transferred at a Point in Time
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		5	12	16	29
Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		21	12	32	19
Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		51	9	90	44
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		2,231	2,250	5,905	6,116
Other revenues	[2],[3]	17	14	78	51
Virginia Electric and Power Company | Renewable Energy Investment Tax Credits
Public Utilities General Disclosures [Line Items]
Operating revenue from contracts with customers		16	11	24	14
Virginia Electric and Power Company | Alternative Revenue Programs
Public Utilities General Disclosures [Line Items]
Other revenues		$ 12	$ 9	$ 63	$ 35

[1] Amounts above include revenue associated with services provided to discontinued operations of $1 million and $4 million for both the three and nine months ended September 30, 2020 and 2019, respectively.

[2] Amounts above include alternative revenue of $51 million and $9 million at Dominion Energy and $12 million and $9 million at Virginia Power for the three months ended September 30, 2020 and 2019, respectively, and $90 million and $44million at Dominion Energy and $63 million and $35 million at Virginia Power for the nine months ended September 30, 2020 and 2019, respectively.

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