Variable Interest Entities (Narrative) (Details) (Virginia Electric and Power Company, USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 generator MW	Jun. 30, 2012
Variable Interest Entities [Line Items]
Long term capacity contract non utility generators (generators)			4
Aggregate generation capacity from long-term power and capacity contracts (MW)			870
Remaining purchase commitments			$ 973
Payment for electric capacity	53		108
Payment for electric energy	26	16	46	35
Shared services purchased	$ 83	$ 77	$ 160	$ 153
Minimum
Variable Interest Entities [Line Items]
Contracts expiry date start range			2015
Maximum
Variable Interest Entities [Line Items]
Contracts expiry date start range			2021