Segment Reporting (Schedule Of Underwriting Results For Operating Segments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Net written premiums	$ 524,338	$ 585,262	$ 531,610	$ 476,167	$ 465,924	$ 458,866	$ 339,432	$ 427,379
Premiums earned	544,812	523,521	490,022	448,006	474,605	427,112	438,470	433,711	2,006,361	1,773,898	1,793,855
Incurred losses and LAE									1,272,156	1,249,744	1,877,603
Commission and brokerage									293,922	310,699	338,655
Other underwriting expenses									193,499	170,604	154,331
Underwriting gain (loss)									246,784	42,851	(576,734)
U.S. Reinsurance [Member]
Segment Reporting Information [Line Items]
Gross written premiums									1,826,044	1,310,683	1,346,830
Net written premiums									909,557	659,692	688,524
Premiums earned									842,341	722,384	697,737
Incurred losses and LAE									424,184	582,436	623,113
Commission and brokerage									159,747	168,606	156,026
Other underwriting expenses									47,177	44,776	39,290
Underwriting gain (loss)									211,233	(73,434)	(120,692)
International [Member]
Segment Reporting Information [Line Items]
Gross written premiums									1,370,615	1,209,523	1,242,609
Net written premiums									610,084	550,732	615,064
Premiums earned									591,695	572,466	636,681
Incurred losses and LAE									315,923	261,473	856,131
Commission and brokerage									114,331	124,552	142,273
Other underwriting expenses									33,910	29,294	27,307
Underwriting gain (loss)									127,531	157,147	(389,030)
Insurance [Member]
Segment Reporting Information [Line Items]
Gross written premiums									1,240,809	1,049,184	969,079
Net written premiums									597,736	481,177	450,423
Premiums earned									572,325	479,048	459,437
Incurred losses and LAE									532,049	405,835	398,359
Commission and brokerage									19,844	17,541	40,356
Other underwriting expenses									112,412	96,534	87,734
Underwriting gain (loss)									$ (91,980)	$ (40,862)	$ (67,012)