Reinsurance (Details 4) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Amounts of letters of credit and cashavailable to us as collateral, plus other potential offsets
Payables to reinsurers	$ 161,271	$ 190,228
Letters of credit	83,053	89,832
Cash	89,215	116,597
Total credits	$ 333,539	$ 396,657