CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Cash flows from operating activities:
Net income (loss)	$ 324,905	$ (264,254)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Net realized investment gains	(44,896)	(67,621)
Net realized and unrealized gains of other investments	(38,079)	(36,542)
Amortization of fixed maturities	61,900	41,041
Other amortization and depreciation	6,892	6,197
Share-based compensation expense	45,446	20,059
Changes in:
Accrued interest receivable	929	(1,020)
Reinsurance recoverable balances	(22,029)	(197,054)
Deferred acquisition costs	(94,886)	(134,847)
Prepaid reinsurance premiums	(32,639)	(24,046)
Reserve for loss and loss expenses	175,606	1,370,237
Unearned premiums	503,761	648,141
Insurance and reinsurance balances, net	(469,234)	(612,334)
Other items	45,884	(155,803)
Net cash provided by operating activities	463,560	592,154
Cash flows from investing activities:
Fixed maturities	(7,093,200)	(7,107,230)
Equity securities	(211,878)	(336,421)
Other investments	(90,084)	(120,000)
Short-term investments	(152,380)	(333,746)
Proceeds from the sale of:
Fixed maturities	5,883,340	6,318,732
Equity securities	289,920	56,296
Other investments	29,250	52,188
Short-term investments	168,433	218,097
Proceeds from redemption of fixed maturities	677,394	751,627
Proceeds from redemption of short-term investments	62,658	99,980
Purchase of other assets	(13,296)	(12,164)
Change in restricted cash and cash equivalents	(20,751)	(79,578)
Net cash used in investing activities	(470,594)	(492,219)
Cash flows from financing activities:
Net proceeds from issuance of preferred shares	393,544	0
Repurchase of preferred shares	(404,073)	0
Repurchase of common shares	(137,969)	(14,810)
Dividends paid - common shares	(62,557)	(147,883)
Dividends paid - preferred shares	(13,803)	(18,438)
Proceeds from issuance of common shares	2,014	5,621
Net cash used in financing activities	(222,844)	(175,510)
Effect of exchange rate changes on foreign currency cash	(960)	17,182
Decrease in cash and cash equivalents	(230,838)	(58,393)
Cash and cash equivalents - beginning of period	981,849	929,515
Cash and cash equivalents - end of period	$ 751,011	$ 871,122