Goodwill and Intangible Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Goodwill [Line Items]
Amortization expense for intangible assets	$ 72	$ 82	$ 78
Acquisition of intangible assets	81
Weighted-average amortization period (years)	10 years
Virginia Electric and Power Company
Goodwill [Line Items]
Amortization expense for intangible assets	22
Acquisition of intangible assets	$ 14
Weighted-average amortization period (years)	5 years