Related-Party Transactions (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Related Party Transaction [Line Items]
Capital expenditures				$ 4,122	$ 4,536
Virginia Electric and Power Company
Related Party Transaction [Line Items]
Commodity purchases from affiliates		$ 170	$ 172	519	416
Services provided by affiliates	[1]	109	105	333	347
Services provided to affiliates		5	5	17	17
Capital expenditures				1,917	1,835
Virginia Electric and Power Company | Affiliate | Services provided by affiliates
Related Party Transaction [Line Items]
Capital expenditures		33	32	104	109
Dominion Energy Gas Holdings, LLC
Related Party Transaction [Line Items]
Commodity purchases from affiliates		2	2	4	7
Services provided by affiliates	[2]	37	34	113	94
Services provided to affiliates		15	16	51	51
Capital expenditures				535	610
Other receivables	[3]	13		13		$ 10
Affiliated notes receivable	[4]	21		21		18
Dominion Energy Gas Holdings, LLC | Services provided by affiliates
Related Party Transaction [Line Items]
Commodity purchases from affiliates	[5]	36	36	106	108
Dominion Energy Gas Holdings, LLC | Affiliate
Related Party Transaction [Line Items]
Imbalances receivable from affiliates						2
Imbalances payable to affiliates	[6]	1		1		$ 4
Dominion Energy Gas Holdings, LLC | Affiliate | Services provided by affiliates
Related Party Transaction [Line Items]
Capital expenditures		$ 13	$ 13	$ 33	$ 37

[1] Includes capitalized expenditures of $33 million and $32 million for the three months ended September 30, 2017 and 2016, respectively, and $104 million and $109 million for the nine months ended September 30, 2017 and 2016, respectively.

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

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

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

[5] Includes capitalized expenditures of $13 million for both the three months ended September 30, 2017 and 2016, respectively, and $33 million and $37 million for the nine months ended September 30, 2017 and 2016, respectively.

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