Commitments and Contingencies (Details) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015 USD ($) Guarantee_contracts	Dec. 31, 2014 USD ($)
Guarantor Obligations [Line Items]
Aggregate exposure outstanding	$ 80,800
Total gross claim liability recorded	$ 0	$ 0
Financial Guarantee Insurance Contracts Outstanding Weighted Average Contract Period	24 years 6 months 3 days	25 years 2 months 12 days
Financial Guarantee Related to Securities Including Some Issued By European Financials [Member]
Guarantor Obligations [Line Items]
Closing number of financial guarantee contracts | Guarantee_contracts	2