Variable Interest Entities (Narrative) (Details) (USD $)	1 Months Ended	12 Months Ended
	Oct. 31, 2010	Dec. 31, 2012	Dec. 31, 2012 Virginia Electric and Power Company MW	Dec. 31, 2011 Virginia Electric and Power Company	Dec. 31, 2010 Virginia Electric and Power Company
Variable Interest Entity [Line Items]
Aggregate generation capacity from long-term power and capacity contracts (MW)			870
Contracts exprity date start range			2015
Contracts exprity date end range			2021
Remaining purchase commitments			$ 1,100,000,000
Payment for electric capacity			214,000,000	211,000,000	213,000,000
Payment for electric energy			83,000,000	125,000,000	164,000,000
Shared services purchased			328,000,000	389,000,000	465,000,000
Annual lease payments		53,000,000
Option price to purchase at end of lease		923,000,000
Percent of original project cost		70.75%
Fair value of property plant and equipment	957,000,000
Amount of debt expected to be recorded from consolidation	896,000,000
Amount of non-controlling interest expected to be recorded from consolidation	$ 61,000,000