Reinsurance (Effect Of Reinsurance On Premiums Written And Earned) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Reinsurance Disclosures [Abstract]
Direct premiums written	$ 976,446	$ 877,430	$ 1,771,757	$ 1,474,849
Direct premiums earned	852,867	719,686	1,681,159	1,257,828
Assumed premiums written	366,932	223,550	931,378	369,431
Assumed premiums earned	336,617	241,664	684,316	343,791
Ceded premiums written	(259,047)	(173,699)	(479,493)	(254,011)
Ceded premiums earned	(223,885)	(176,531)	(450,501)	(252,213)
Net premiums written	1,084,331	927,281	2,223,642	1,590,269
Net premiums earned	$ 965,599	$ 784,819	$ 1,914,974	$ 1,349,406