Variable Interest Entities (Narrative) (Details) (Virginia Electric and Power Company, USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 MW generator	Mar. 31, 2013
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	$ 807
Payment for electric capacity	56	55
Payment for electric energy	54	20
Shared services purchased	$ 108	$ 77
Minimum
Variable Interest Entities [Line Items]
Contracts expiry date start range	2015
Maximum
Variable Interest Entities [Line Items]
Contracts expiry date start range	2021