Employee Benefit Plans (Narrative) (Details) - USD ($)		9 Months Ended
		Sep. 30, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Contributions to defined benefit pension plans and OPEB plans		$ 0
Expected contribution to voluntary employees' beneficiary association		12,000,000
Other deferred credits and other liabilities
Defined Benefit Plan Disclosure [Line Items]
Amounts due to Dominion		292,000,000	$ 219,000,000
Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Contributions to defined benefit pension plans and OPEB plans		0
Expected contribution to voluntary employees' beneficiary association		12,000,000
Amounts due from Dominion	[1]	1,000,000	3,000,000
Pension Benefits | Dominion Gas Holdings, LLC | Affiliate | Noncurrent Pension and Other Postretirement Benefit Assets
Defined Benefit Plan Disclosure [Line Items]
Amounts due from Dominion		642,000,000	614,000,000
Other Postretirement Benefits | Dominion Gas Holdings, LLC | Affiliate | Other deferred credits and other liabilities
Defined Benefit Plan Disclosure [Line Items]
Amounts due to Dominion		$ 4,000,000	$ 7,000,000

[1] Amounts are presented in other current assets in Dominion Gas' Consolidated Balance Sheets.