SCHEDULE IV - SUPPLEMENTARY REINSURANCE INFORMATION (DETAILS) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
SCHEDULE IV - SUPPLEMENTARY REINSURANCE INFORMATION [Abstract]
Direct gross premium	$ 1,696,600	$ 1,619,880	$ 1,516,031
Ceded to other companies	676,719	602,996	770,866
Assumed from other companies	2,399,553	2,130,656	2,071,264
Net amount	$ 3,419,434	$ 3,147,540	$ 2,816,429
Percentage of amount assumed to net	70.20%	67.70%	73.50%