Employee Benefit Plans (Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 31	$ 28	$ 63	$ 57
Interest cost	72	73	144	145
Expected return on plan assets	(133)	(125)	(266)	(250)
Amortization of prior service cost (credit)	1	1	1	2
Amortization of net actuarial loss	40	28	80	56
Net periodic benefit cost (credit)	11	5	22	10
Pension Benefits | Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	3	7	6
Interest cost	7	7	14	14
Expected return on plan assets	(32)	(28)	(63)	(57)
Amortization of prior service cost (credit)	0	0	0	0
Amortization of net actuarial loss	5	4	10	9
Net periodic benefit cost (credit)	(16)	(14)	(32)	(28)
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	10	8	20	16
Interest cost	16	16	33	33
Expected return on plan assets	(30)	(27)	(59)	(55)
Amortization of prior service cost (credit)	(6)	(7)	(13)	(14)
Amortization of net actuarial loss	2	1	3	1
Net periodic benefit cost (credit)	(8)	(9)	(16)	(19)
Other Postretirement Benefits | Dominion Gas Holdings, LLC
Defined Benefit Plan Disclosure [Line Items]
Service cost	1	2	3	3
Interest cost	4	3	7	6
Expected return on plan assets	(6)	(6)	(12)	(11)
Amortization of prior service cost (credit)	0	(1)	0	(1)
Amortization of net actuarial loss	0	0	1	0
Net periodic benefit cost (credit)	$ (1)	$ (2)	$ (1)	$ (3)