Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013 Guarantee_contracts	Dec. 31, 2012 Guarantee_contracts
Guarantor Obligations [Line Items]
Opening number of financial guarantee contracts	4	4
Number of financial guarantee contracts matured, prepaid or commuted during the period	0	0
Closing number of financial guarantee contracts	4	4
Principal outstanding	$ 115,464	$ 115,464
Interest outstanding	0	0
Aggregate exposure outstanding	115,464	115,464
Total gross claim liability recorded	1,399	1,399
Total unearned premiums and fees recorded	206	279
Weighted average term to maturity	24 years 10 months 24 days	25 years 4 months 24 days
Financial Guarantee Related to Future Scheduled Repayments On Government Subsidized Housing Project [Member]
Guarantor Obligations [Line Items]
Aggregate exposure outstanding	7,200
Financial Guarantee Related to Securities Including Some Issued By European Financials [Member]
Guarantor Obligations [Line Items]
Closing number of financial guarantee contracts	3
Aggregate exposure outstanding	$ 108,300