Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
CASH FROM (USED IN) OPERATING ACTIVITIES:
Net income to common stockholders	$ 369,546	$ 345,103
Adjustments to reconcile net income to net cash from operating activities:
Net investment gains	(96,896)	(94,003)
Depreciation and amortization	80,049	65,089
Noncontrolling interests	367	41
Investment funds	(48,299)	(50,124)
Stock incentive plans	18,163	21,070
Change in:
Arbitrage trading account	(249)	(2,355)
Premiums and fees receivable	(161,660)	(192,803)
Reinsurance accounts	(168,863)	(90,587)
Deferred policy acquisition costs	(51,629)	(34,843)
Income taxes	(25,396)	5,719
Reserves for losses and loss expenses	341,266	215,993
Unearned premiums	363,354	284,908
Other	6,942	(19,859)
Net cash from (used in) operating activities	626,695	453,349
CASH FROM (USED IN) INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	891,357	549,876
Proceeds from sale of equity securities	222,396	233,239
Distributions from (contributions to) investment funds	(57,812)	(6,293)
Proceeds from maturities and prepayments of fixed maturity securities	2,244,665	1,659,751
Purchase of fixed maturity securities	(3,198,204)	(2,510,322)
Purchase of equity securities	(184,829)	(218,490)
Real estate purchased	(47,279)	(71,348)
Change in loans receivable	(99,356)	(106,721)
Net additions to real estate, furniture and equipment	(49,425)	(22,319)
Change in balances due to security brokers	(37,554)	79,344
Cash distributed in connection with business disposition	(21,408)
Payment for business purchased, net of cash acquired	(38,556)	0
Net cash from (used in) investing activities	(376,005)	(413,283)
CASH FROM (USED IN) FINANCING ACTIVITIES:
Repayment of senior notes and other debt	(463,600)	0
Net proceeds from issuance of debt	349,423	375,641
Net proceeds from stock options exercised	51	8,667
Cash dividends to common stockholders	(39,336)	(35,730)
Purchase of common treasury shares	(39,370)	(121,362)
Other, net	7,290	15,799
Net cash from (used in) financing activities	(185,542)	243,015
Net impact on cash due to change in foreign exchange rates	(4,492)	(5,259)
Net change in cash and cash equivalents	60,656	277,822
Cash and cash equivalents at beginning of year	905,670	911,742
Cash and cash equivalents at end of period	$ 966,326	$ 1,189,564