Related-Party Transactions (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Virginia Electric and Power Company
Related Party Transaction [Line Items]
Commodity purchases from affiliates		$ 930	$ 674	$ 571
Services provided by affiliates	[1]	450	453	454
Virginia Electric and Power Company | Affiliated Entity
Related Party Transaction [Line Items]
Services provided to related parties		24	25	22
Dominion Energy Gas Holdings, LLC
Related Party Transaction [Line Items]
Services provided to related parties	[2]	216	156	128
Commodity purchases from affiliates		58	70	69
Services provided by affiliates	[3]	131	143	141
Other receivables	[4]	13	12
Customer receivables from related parties		1	1
Affiliated notes receivable	[5]	16	20
Dominion Energy Gas Holdings, LLC | Affiliated Entity
Related Party Transaction [Line Items]
Services provided to related parties		6	5	$ 9
Imbalances receivable from affiliates		1	$ 1
Imbalances payable to affiliates	[6]	$ 13

[1] Includes capitalized expenditures of $145 million, $144 million and $144 million for the year ended December 31, 2018, 2017 and 2016, respectively.

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

[3] Includes capitalized expenditures of $37 million, $45 million and $49 million for the year ended December 31, 2018, 2017 and 2016, respectively.

[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.