Investments (Details 2) (USD $) In Thousands	Jun. 30, 2011
Fixed maturities held to maturity:
Due after one year through five years, Amortized cost	$ 55,209
Due after five years through ten years, Amortized cost	364,297
Due after ten years, Amortized cost	768,085
Total	1,187,591
Due after one year through five years, Fair value	60,826
Due after five years through ten years, Fair value	383,097
Due after ten years, Fair value	804,578
Total	1,248,501
Non-asset backed and non-U.S. Government agencies
Fixed maturities available for sale:
Due in one year or less, Amortized cost	423,937
Due after one year through five years, Amortized cost	3,898,992
Due after five years through ten years, Amortized cost	2,149,447
Due after ten years, Amortized cost	3,022,794
Due in one year or less, Fair value	427,811
Due after one year through five years, Fair value	3,977,201
Due after five years through ten years, Fair value	2,237,739
Due after ten years, Fair value	3,081,891
Asset backed and U.S. Government agencies
Fixed maturities available for sale:
No single maturity date, amortized cost	1,531,315
No single maturity date, fair value	$ 1,524,753