Commitments and Contingencies Commitment and Contingencies (Schedule of Long Term Purchase Commitments) (Details) (Virginia Electric and Power Company, USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Long-term Purchase Commitment [Line Items]
Present value of total commitment for capacity payments	$ 1,400,000,000
Purchased electric capacity
Long-term Purchase Commitment [Line Items]
2013	350,000,000	[1]
2014	358,000,000	[1]
2015	337,000,000	[1]
2016	275,000,000	[1]
2017	181,000,000	[1]
Thereafter	327,000,000	[1]
Total	1,828,000,000	[1]
Payments	337,000,000		338,000,000	344,000,000
Energy payments
Long-term Purchase Commitment [Line Items]
Payments	$ 214,000,000		$ 275,000,000	$ 303,000,000

[1] Commitments represent estimated amounts payable for capacity under power purchase contracts with qualifying facilities and independent power producers, the last of which ends in 2021. Capacity payments under the contracts are generally based on fixed dollar amounts per month, subject to escalation using broad-based economic indices. At December 31, 2012, the present value of Virginia Power's total commitment for capacity payments is $1.4 billion. Capacity payments totaled $337 million, $338 million, and $344 million, and energy payments totaled $214 million, $275 million, and $303 million for 2012, 2011 and 2010, respectively.