Reserves For Losses And LAE (Summary Of Activity In The Reserve For Losses And LAE) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reserves For Losses And LAE [Abstract]
Gross reserves at January 1	$ 7,843,856	$ 7,653,229	$ 8,143,055
Less reinsurance recoverable	(3,875,073)	(3,702,782)	(3,427,385)	$ (3,444,970)
Net reserves at January 1	4,141,074	4,225,844	4,698,085
Incurred related to: Current year	1,326,015	1,314,887	1,227,525
Incurred related to: Prior years	(6,454)	39,206	44,631
Total incurred losses and LAE	1,319,561	1,354,093	1,272,156
Paid related to: Current year	357,819	452,662	464,914
Paid related to: Prior years	946,337	926,819	1,209,941
Total paid losses and LAE	1,304,156	1,379,481	1,674,855
Foreign exchange/translation adjustment	(90,832)	(59,382)	(69,542)
Net reserves at December 31	4,065,647	4,141,074	4,225,844
Plus reinsurance recoverable	3,875,073	3,702,782	3,427,385
Gross reserves at December 31	$ 7,940,720	$ 7,843,856	$ 7,653,229