Commitments and Contingencies (Nuclear Insurance) (Details)	Dec. 31, 2016 USD ($)
Millstone
Guarantor Obligations [Line Items]
Property insurance coverage	$ 1,700,000
Kewaunee
Guarantor Obligations [Line Items]
Property insurance coverage	1,060,000
Surry | Virginia Electric and Power Company
Guarantor Obligations [Line Items]
Property insurance coverage	1,700,000	[1]
North Anna | Virginia Electric and Power Company
Guarantor Obligations [Line Items]
Property insurance coverage	1,700,000	[1]
Surry and North Anna
Guarantor Obligations [Line Items]
Coverage amount	$ 200,000,000

[1] Surry and North Anna share a blanket property limit of $200 million.