Variable Interest Entities (Narrative) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($) generator	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) MW generator	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Variable Interest Entity [Line Items]
Securities due within one year	$ 2,788		$ 2,788		$ 1,709	[1]
Long term debt	30,886		30,886		30,231	[1]
Virginia Electric and Power Company
Variable Interest Entity [Line Items]
Securities due within one year	851		851		678	[2]
Long term debt	10,495		10,495		9,852	[2]
Dominion Energy Gas Holdings, LLC
Variable Interest Entity [Line Items]
Long term debt	3,564		3,564		3,528	[3]
Variable Interest Entity, Primary Beneficiary | SBL Holdco
Variable Interest Entity [Line Items]
Securities due within one year	$ 29		$ 29
Long term debt					$ 356
Variable Interest Entity (VIE) or Potential VIE, Information Unavailability | Virginia Electric and Power Company
Variable Interest Entity [Line Items]
Long term capacity contract non utility generators (generators) | generator			3
Number of expired non-utility generators | generator	2
Aggregate generation capacity from long-term power and capacity contracts (MW) | MW			218
Remaining purchase commitments	$ 213		$ 213
Payment for electric capacity	17	$ 37	73	$ 111
Payment for electric energy	5	11	20	23
Variable Interest Entity, Not Primary Beneficiary | Virginia Electric and Power Company | DES
Variable Interest Entity [Line Items]
Shared services purchased	83	80	251	268
Variable Interest Entity, Not Primary Beneficiary | Dominion Energy Gas Holdings, LLC | DES
Variable Interest Entity [Line Items]
Shared services purchased	$ 31	$ 31	$ 93	$ 95

[1] Dominion Energy’s Consolidated Balance Sheet at December 31, 2016 has been derived from the audited Consolidated Balance Sheet at that date.

[2] Virginia Power’s Consolidated Balance Sheet at December 31, 2016 has been derived from the audited Consolidated Balance Sheet at that date.

[3] Dominion Energy Gas’ Consolidated Balance Sheet at December 31, 2016 has been derived from the audited Consolidated Balance Sheet at that date.