Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FROM OPERATING ACTIVITIES:
Net income to common stockholders	$ 601,916	$ 503,694	$ 648,884
Adjustments to reconcile net income to net cash from operating activities:
Net investment gains	(267,005)	(92,324)	(254,852)
Depreciation and amortization	86,051	85,139	88,836
Noncontrolling interests	1,569	413	719
Investment funds	(99,301)	(62,228)	(131,649)
Stock incentive plans	37,174	32,123	28,068
Change in:
Arbitrage trading account	(10,633)	(7,173)	(50,817)
Premiums and fees receivable	(60,403)	(60,942)	(104,174)
Reinsurance accounts	(235,455)	(31,930)	(33,445)
Deferred policy acquisition costs	(25,912)	(29,860)	(42,789)
Increase (Decrease) in Income Taxes	42,632	20,428	(40,935)
Current Income Tax Expense (Benefit)	283,173	176,832	271,306
Deferred income taxes	9,012	47,260	30,812
Reserves for losses and loss expenses	572,196	397,685	376,617
Unearned premiums	149,683	142,699	277,826
Other	46,852	(63,680)	(58,254)
Net cash from operating activities	848,376	881,304	734,847
CASH FLOWS USED IN INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	2,440,310	1,388,680	633,459
Proceeds from sale of equity securities	143,042	15,833	113,251
Distributions from investment funds	142,601	177,424	69,319
Proceeds from maturities and prepayments of fixed maturity securities	2,189,365	2,999,339	2,605,839
Purchase of fixed maturity securities	(5,541,202)	(4,455,223)	(4,292,165)
Purchase of equity securities	(202,736)	(29,526)	(31,207)
Real estate purchased	(299,123)	(222,659)	(213,159)
Proceeds from Sale of Buildings	0	0	343,723
Change in loans receivable	166,327	48,909	21,608
Net additions to property, furniture and equipment	(50,829)	(63,562)	(41,958)
Change in balances due from security brokers	20,992	(22,666)	32,617
Proceeds from Divestiture of Businesses, Net of Cash Divested	250,216	0	15,783
Payment for business purchased, net of cash acquired	(53,451)	(7,312)	(65,421)
Net cash used in investing activities	(794,488)	(170,763)	(808,311)
CASH FLOWS USED IN FINANCING ACTIVITIES:
Net proceeds from issuance of debt	388,769	9,056	354,012
Repayment of senior notes and other debt	(75,487)	(281,086)	(3,700)
Cash dividends to common stockholders	(183,999)	(58,034)	(181,489)
Purchase of common treasury shares	(132,392)	(223,652)	(238,933)
Other, net	(3,823)	(1,602)	337
Net cash used in financing activities	(6,932)	(555,318)	(69,773)
Net impact on cash due to change in foreign exchange rates	(15,302)	(66,033)	(22,060)
Net increase (decrease) in cash and cash equivalents	31,654	89,190	(165,297)
Cash and cash equivalents at beginning of year	763,631	674,441
Cash and cash equivalents at end of year	$ 795,285	$ 763,631	$ 674,441