Reinsurance (Premiums Written And Earned And Incurred Losses And LAE)(Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reinsurance [Abstract]
Written premiums : Direct									$ 1,511,217	$ 1,179,034	$ 1,240,761
Written premiums: Assumed									3,484,414	3,786,260	3,196,707
Written premiums: Ceded									(2,902,348)	(2,858,320)	(2,320,091)
Net written premium	$ 513,319	$ 599,073	$ 472,464	$ 508,427	$ 502,627	$ 611,916	$ 492,727	$ 499,704	2,093,283	2,106,974	2,117,377
Premiums earned: Direct									1,439,795	1,148,297	1,183,542
Premiums earned: Assumed									3,637,484	3,685,784	3,024,825
Premium earned: Ceded									(2,933,519)	(2,720,355)	(2,202,006)
Net premiums earned									2,143,760	2,113,726	2,006,361
Incurred losses and LAE: Direct									1,235,012	1,073,485	1,153,004
Incurred losses and LAE: Assumed									1,728,661	1,855,057	1,473,297
Incurred losses and LAE: Ceded									(1,644,112)	(1,574,449)	(1,354,145)
Incurred losses and loss adjustment expenses									$ 1,319,561	$ 1,354,093	$ 1,272,156