Schedule IV Reinsurance (Details) (Reinsurance Premiums for Insurance Companies, by Product Segment [Domain], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reinsurance Premiums for Insurance Companies, by Product Segment [Domain]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Premiums for Insurance Companies, by Product Segment, Gross Amount	$ 762,428	$ 891,167	$ 919,778
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Ceded to Other Companies	38,740	94,497	139,626
Reinsurance Premiums for Insurance Companies, by Product Segment, Amount Assumed from Other Companies	32,337	29,063	45,749
Reinsurance Premiums for Insurance Companies, by Product Segment, Net Amount	$ 756,025	$ 825,733	$ 825,901
Reinsurance Premiums for Insurance Companies, by Product Segment, Percentage of Amount Assumed to Net	4.28%	3.52%	5.54%