Commitment and Contingencies (Schedule of Long Term Purchase Commitments) (Details) (Virginia Electric and Power Company, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Long-term Purchase Commitment [Line Items]
Present value of total commitment for capacity payments	$ 833
Purchased electric capacity
Long-term Purchase Commitment [Line Items]
2015	313	[1]
2016	250	[1]
2017	158	[1]
2018	104	[1]
2019	65	[1]
Thereafter	99	[1]
Total	989	[1]
Payments	330		345	337
Energy payments
Long-term Purchase Commitment [Line Items]
Payments	$ 304		$ 236	$ 214

[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, 2014, the present value of Virginia Power's total commitment for capacity payments is $833 million. Capacity payments totaled $330 million, $345 million, and $337 million, and energy payments totaled $304 million, $236 million, and $214 million for the years ended 2014, 2013 and 2012, respectively.