Employee Benefit Plans (Components of AOCI and Regulatory Assets and Liabilities) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 25
Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	3
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	160
Prior service (credit) cost	2
Pension Benefits | Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	20
Prior service (credit) cost	1
Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	6
Prior service (credit) cost	(27)
Other Postretirement Plans | Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	2
Prior service (credit) cost	$ 0