Commitments and Contingencies (Nuclear Insurance) (Details) (USD $)	Dec. 31, 2012
Millstone
Guarantor Obligations [Line Items]
Property insurance coverage	$ 2,750,000
Kewaunee
Guarantor Obligations [Line Items]
Property insurance coverage	1,800,000
Surry | Virginia Electric and Power Company
Guarantor Obligations [Line Items]
Property insurance coverage	2,550,000	[1]
North Anna | Virginia Electric and Power Company
Guarantor Obligations [Line Items]
Property insurance coverage	2,550,000	[1]
Surry and North Anna
Guarantor Obligations [Line Items]
Coverage amount	$ 1,000,000,000

[1] Surry and North Anna share a blanket property limit of $1 billion.