Related-Party Transactions (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Virginia Electric and Power Company
Related Party Transaction [Line Items]
Commodity purchases from affiliates		$ 119	$ 139	$ 391	$ 537
Services provided by affiliates	[1]	161	112	280	232
Virginia Electric and Power Company | Affiliated Entity
Related Party Transaction [Line Items]
Services provided to related parties		8	5	14	11
Dominion Energy Gas Holdings, LLC
Related Party Transaction [Line Items]
Commodity purchases from affiliates		3		6	1
Services provided by affiliates	[2]	50	33	85	66
Services provided to related parties	[3]	33	61	70	113
Commodity purchases from affiliates			(2)
Other receivables	[4]	10		10		$ 13
Customer receivables from related parties						1
Affiliated notes receivable	[5]	14		14		16
Dominion Energy Gas Holdings, LLC | Affiliated Entity
Related Party Transaction [Line Items]
Services provided to related parties		12	$ 16	27	$ 34
Imbalances receivable from affiliates		$ 4		$ 4		1
Imbalances payable to affiliates	[6]					$ 13

[1] Includes capitalized expenditures of $34 million and $38 million for the three months ended June 30, 2019 and 2018, respectively, and $67 million and $75 million for the six months ended June 30, 2019 and 2018, respectively.

[2] Includes capitalized expenditures of $7 million for both the three months ended June 30, 2019 and 2018, and $12 million and $17 million for the six months ended June 30, 2019 and 2018, respectively.

[3] Amounts primarily attributable to Atlantic Coast Pipeline, a related-party VIE.

[4] Represents amounts due from Atlantic Coast Pipeline, a related-party VIE.

[5] Amounts are presented in other deferred charges and other assets in Dominion Energy Gas’ Consolidated Balance Sheets.

[6] Amounts are presented in other current liabilities in Dominion Energy Gas’ Consolidated Balance Sheets.