Employee Benefit Plans (AOCI and regulatory assets and liabilities that have not been recognized as components of periodic benefit (credit) cost) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	$ (416)		$ (324)		$ (877)
Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	(86)		(58)		(140)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	2,382		1,709
Prior service (credit) cost	7		10
Total	2,389	[1]	1,719	[1]
Related expenses	2,400		1,700
Amount included in AOCI	1,400		1,000
Pension Benefits | Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	303		279
Prior service (credit) cost	1		2
Total	304	[1]	281	[1]
Related expenses	304		281
Amount included in AOCI	112		104
Other Postretirement Plans
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	139		(40)
Prior service (credit) cost	(233)		(271)
Total	(94)	[1]	(311)	[1]
Related expenses	(94)		(311)
Amount included in AOCI	(81)		(156)
Other Postretirement Plans | Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Net actuarial (gain) loss	43		3
Prior service (credit) cost	7		(4)
Total	50	[1]	(1)	[1]
Amount included in AOCI	$ 50		$ (1)

[1] As of December 31, 2014, of the $2.4 billion and $(94) million related to pension benefits and other postretirement benefits, $1.4 billion and $(81) million, respectively, are included in AOCI, with the remainder included in regulatory assets and liabilities. As of December 31, 2013, of the $1.7 billion and $(311) million related to pension benefits and other postretirement benefits, $1.0 billion and $(156) million, respectively, are included in AOCI, with the remainder included in regulatory assets and liabilities.