Regulatory Assets and Liabilities (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Entity Information [Line Items]
Regulatory assets past expenditures not earning return	$ 102
Period expenditures not earning return are to be recovered	2 years
Virginia Electric and Power Company
Entity Information [Line Items]
Regulatory assets past expenditures not earning return	$ 65