CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues
Net premiums earned	$ 3,314,961	$ 2,947,410	$ 2,791,764
Net investment income	362,430	406,892	464,478
Other insurance related income (loss)	2,396	2,073	(129,681)
Net realized investment gains (losses):
Other-than-temporary impairment (OTTI) losses	(16,446)	(19,216)	(339,994)
Non-credit portion of OTTI losses recognized in other comprehensive income	585	1,284	2,559
Other realized investment gains	137,300	213,030	25,851
Total net realized investment gains (losses)	121,439	195,098	(311,584)
Total revenues	3,801,226	3,551,473	2,814,977
Expenses
Net losses and loss expenses	2,675,052	1,677,132	1,423,872
Acquisition costs	587,469	488,712	420,495
General and administrative expenses	459,151	449,885	370,157
Foreign exchange losses (gains)	(44,582)	(15,535)	28,561
Interest expense and financing costs	62,598	55,876	32,031
Total expenses	3,739,688	2,656,070	2,275,116
Income before income taxes	61,538	895,403	539,861
Income tax expense	15,233	38,680	41,975
Net income	46,305	856,723	497,886
Preferred share dividends	36,875	36,875	36,875
Net income available to common shareholders	$ 9,430	$ 819,848	$ 461,011
Net income per common share:
Basic net income	$ 0.08	$ 6.74	$ 3.36
Diluted net income	$ 0.07	$ 6.02	$ 3.07
Weighted average number of common shares outstanding:
Weighted average number of common shares outstanding - basic	122,499	121,728	137,279
Weighted average number of common shares outstanding - diluted	128,122	136,199	150,371
Cash dividends declared per common share	$ 0.93	$ 0.86	$ 0.81