CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Cash flows from operating activities:
Net income	$ 350,729	$ 395,280
Adjustments to reconcile net income to net cash provided by operating activities:
Net realized investment gains	(43,882)	(60,713)
Net realized and unrealized gains on other investments	(49,252)	(55,279)
Amortization of fixed maturities	56,122	72,853
Other amortization and depreciation	10,919	11,413
Share-based compensation expense, net of cash payments	27,763	30,936
Changes in:
Accrued interest receivable	5,929	2,122
Reinsurance recoverable balances	(20,663)	(117,622)
Deferred acquisition costs	(167,095)	(153,821)
Prepaid reinsurance premiums	(5,590)	(15,852)
Reserve for loss and loss expenses	217,924	284,086
Unearned premiums	721,870	754,363
Insurance and reinsurance balances, net	(696,877)	(670,328)
Other items	(15,654)	(20,518)
Net cash provided by operating activities	392,243	456,920
Cash flows from investing activities:
Fixed maturities	(6,581,006)	(6,079,805)
Equity securities	(209,381)	(130,544)
Other investments	(37,512)	(109,232)
Short-term investments	(463,051)	(72,093)
Proceeds from the sale of:
Fixed maturities	5,784,439	5,334,043
Equity securities	197,354	218,523
Other investments	88,080	45,634
Short-term investments	391,966	115,072
Proceeds from redemption of fixed maturities	532,445	778,819
Proceeds from redemption of short-term investments	16,503	19,119
Purchase of other assets	(16,039)	(10,641)
Change in restricted cash and cash equivalents	(80,827)	(14,710)
Net cash provided by (used in) investing activities	(377,029)	94,185
Cash flows from financing activities:
Net proceeds from issuance of senior notes	494,344	0
Net proceeds from issuance of preferred shares	0	218,449
Repurchase of preferred shares	0	(100,000)
Repurchase of common shares	(318,082)	(340,621)
Dividends paid - common shares	(60,903)	(62,312)
Dividends paid - preferred shares	(20,044)	(18,750)
Proceeds from issuance of common shares	4,698	14,819
Net cash provided by (used in) financing activities	100,013	(288,415)
Effect of exchange rate changes on foreign currency cash and cash equivalents	5,473	(11,702)
Increase in cash and cash equivalents	120,700	250,988
Cash and cash equivalents - beginning of period	923,326	759,817
Cash and cash equivalents - end of period	$ 1,044,026	$ 1,010,805