Reinsurance (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Amounts of letters of credit and cash deposits held by us as collateral, plus other credits available for potential offset
Payables to reinsurers	$ 190,228	$ 195,806
Letters of credit	89,832	120,589
Cash	116,597	83,731
Total credits	$ 396,657	$ 400,126