Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Cash flows provided by (used in) operating activities
Net (loss) income	$ (61,886)	$ 61,404
Adjustments to reconcile net income to cash provided by (used in) operating activities:
Share compensation expenses	19,677	13,422
Amortization of discount on senior notes	54	27
Net realized (gains) on investments	(17,931)	(23,839)
Net unrealized (gains) on investments	(5,698)	(57,053)
Amortization of intangible assets	2,080	2,080
Foreign exchange (gains) losses on cash and cash equivalents included in net income	(12,729)	17,129
Amortization of premium on fixed maturities	16,247	8,410
Change in:
Premiums receivable	(475,119)	(383,671)
Deferred acquisition costs	(52,827)	(53,628)
Prepaid reinsurance premiums	(106,312)	(112,607)
Loss reserves recoverable	(155,002)	(13,488)
Paid losses recoverable	(2,825)	(9,364)
Income taxes recoverable	(2,400)	860
Accrued investment income	12,406	(653)
Other assets	9,351	(11,550)
Reserve for losses and loss expenses	575,832	367,779
Unearned premiums	464,256	452,499
Reinsurance balances payable	116,080	35,240
Deferred income taxes	(2,611)	1,452
Accounts payable and accrued expenses	(11,029)	(30,867)
Net cash provided by operating activities	309,614	263,582
Cash flows provided by (used in) investing activities
Proceeds on sales of investments	2,654,804	2,933,352
Proceeds on maturities of investments	195,055	198,637
Purchases of fixed maturities	(2,613,981)	(3,244,072)
(Purchases) sales of short-term investments, net	(451,706)	211,801
Sales of other investments	3,809	11,610
Decrease (increase) in securities lending collateral	960	(9,894)
Net cash (used in) provided by investing activities	(211,059)	101,434
Cash flows provided by (used in) financing activities
Net proceeds on issuance of senior notes		246,793
Issuance (redemption) of common shares, net	6,238	(12)
Purchases of common shares under share repurchase program	(5,995)	(444,079)
Dividends paid	(54,000)	(55,994)
(Decrease) increase in securities lending payable	(960)	9,894
Third party investment in noncontrolling interest	134,301
Net cash provided by (used in) by financing activities	79,584	(243,398)
Effect of foreign currency rate changes on cash and cash equivalents	17,042	(16,714)
Net increase in cash	195,181	104,904
Cash and cash equivalents - beginning of period	620,740	387,585
Cash and cash equivalents - end of period	815,921	492,489
Taxes (recovered) paid during the period	(3,373)	1,335
Interest paid during the period	$ 23,823	$ 12,729