Consolidated Statements of Operations and Comprehensive (Loss) Income (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenues
Gross premiums written	$ 4,633,054	$ 4,885,266	$ 4,000,888
Net premiums written	4,486,329	4,705,116	3,948,704
Decrease in unearned premiums	161,425	71,355	171,121
Net premiums earned	4,647,754	4,776,471	4,119,825
Net investment income	629,148	672,782	596,071
Net realized and unrealized investment gains (losses)	66,692	401,482	591,707
Net realized gain on purchase of capital efficient notes	0	0	88,427
Other income	7,915	10,470	22,312
Total revenues	5,351,509	5,861,205	5,418,342
Expenses
Losses and loss expenses and life policy benefits	4,372,570	3,283,618	2,295,296
Acquisition costs	938,361	972,537	885,214
Other operating expenses	434,846	539,751	430,808
Interest expense	48,949	44,413	28,301
Amortization of intangible assets	36,405	31,461	(6,133)
Net foreign exchange (gains) losses	(34,675)	20,686	1,464
Total expenses	5,796,456	4,892,466	3,634,950
(Loss) income before taxes and interest in (losses) earnings of equity investments	(444,947)	968,739	1,783,392
Income tax expense	68,972	128,784	262,090
Interest in (losses) earnings of equity investments	(6,372)	12,597	15,552
Net (loss) income	(520,291)	852,552	1,536,854
Preferred dividends	47,020	34,525	34,525
Net (loss) income available to common shareholders	(567,311)	818,027	1,502,329
Comprehensive (loss) income
Net (loss) income	(520,291)	852,552	1,536,854
Change in currency translation adjustment	(11,834)	(66,742)	47,955
Change in other accumulated comprehensive (loss) income	(4,866)	(14,129)	14,164
Comprehensive (loss) income	$ (536,991)	$ 771,681	$ 1,598,973
Per share data
Basic net (loss) income	$ (8.40)	$ 10.65	$ 23.93
Diluted net (loss) income	$ (8.40)	$ 10.46	$ 23.51
Weighted average number of common shares outstanding	67,558,732	76,839,519	62,786,234
Weighted average number of common shares and common share equivalents outstanding	67,558,732	78,234,312	63,890,638
Dividends declared per common share	$ 2.35	$ 2.05	$ 1.88