Equity (Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized losses on derivatives-hedging activities, net of tax	$ (178)	$ (288)
Net unrealized gains on nuclear decommissioning trust funds, net of tax	548	474
Net unrecognized pension and other postretirement benefit costs, net of tax	(782)	(510)
Other comprehensive loss from equity method investees, net of tax	(4)	0
Total AOCI	(416)	(324)	(877)
Net unrealized gains on derivatives-hedging activities, tax	116	196
Net unrealized gains on nuclear decommissioning trust funds, tax	(333)	(307)
Net unrecognized pension and other postretirement benefit costs, tax	530	365
Other comprehensive loss from equity method investees, tax	3	0
Virginia Electric and Power Company
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized losses on derivatives-hedging activities, net of tax	(7)	0
Net unrealized gains on nuclear decommissioning trust funds, net of tax	57	48
Total AOCI	50	48	25
Net unrealized gains on derivatives-hedging activities, tax	4	0
Net unrecognized pension and other postretirement benefit costs, tax	(35)	(30)
Dominion Gas Holdings, LLC
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net unrealized losses on derivatives-hedging activities, net of tax	(20)	3
Net unrealized gains on nuclear decommissioning trust funds, net of tax	(66)	(61)
Total AOCI	(86)	(58)	(140)
Net unrealized gains on derivatives-hedging activities, tax	11	(1)
Net unrecognized pension and other postretirement benefit costs, tax	$ 46	$ 43