Shareholders' Equity (Accumulated Other Comprehensive Income (Loss)) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Net unrealized gains on derivatives-hedging activities, net of tax	$ (122)	$ (54)
Net unrealized gains on nuclear decommissioning trust funds, net of tax	326	243
Net unrecognized pension and other postretirement benefit costs, net of tax	(1,081)	(799)
Total AOCI	(877)	(610)
Net unrealized gains (losses) on derivatives-hedging activities, tax	87	48
Net unrealized gains (losses) on nuclear decommissioning trust funds, tax	(206)	(154)
Net unrecognized pension and other postretirement benefit costs, tax	754	568
Virginia Electric and Power Company
Net unrealized gains on derivatives-hedging activities, net of tax	(6)	(3)
Net unrealized gains on nuclear decommissioning trust funds, net of tax	31	22
Total AOCI	25	19
Net unrealized gains (losses) on derivatives-hedging activities, tax	3	2
Net unrecognized pension and other postretirement benefit costs, tax	$ (19)	$ (14)