Reinsurance (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Effect of reinsurance transactions on our premium, loss and loss adjustment expense and policy acquisition costs
Direct written premium	$ 616,938	$ 603,844	$ 1,911,619	$ 1,826,610
Reinsurance assumed	61,975	61,919	296,942	313,395
Reinsurance ceded	(157,179)	(135,456)	(478,609)	(409,206)
Net written premium	521,734	530,307	1,729,952	1,730,799
Direct earned premium	622,464	601,572	1,860,093	1,795,109
Reinsurance assumed	81,594	90,988	252,902	259,870
Reinsurance ceded	(147,390)	(128,910)	(433,785)	(378,857)
Net earned premium	556,668	563,650	1,679,210	1,676,122
Direct loss and loss adjustment expense	517,382	301,306	1,210,862	1,029,227
Reinsurance assumed	8,607	35,108	119,315	96,143
Reinsurance ceded	(205,613)	(32,400)	(337,630)	(155,603)
Net loss and loss adjustment expense	320,376	304,014	992,547	969,767
Policy acquisition costs	105,254	101,698	309,285	299,854
Ceding commissions	(39,612)	(34,078)	(105,898)	(88,300)
Net policy acquisition costs	$ 65,642	$ 67,620	$ 203,387	$ 211,554