Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH (USED IN) FROM OPERATING ACTIVITIES:
Net income to common stockholders	$ 166,396	$ 123,447
Adjustments to reconcile net income to net cash from operating activities:
Net realized and unrealized gains on investments	(48,464)	(52,348)
Depreciation and amortization	29,027	18,133
Noncontrolling interests	1,177	1,227
Investment funds	(40,354)	(26,649)
Stock incentive plans	9,434	10,780
Change in:
Arbitrage trading account	497	2,350
Premiums and fees receivable	(74,492)	(59,244)
Reinsurance accounts	(100,379)	67,205
Deferred policy acquisition costs	(6,851)	(6,126)
Income taxes	50,505	50,595
Reserves for losses and loss expenses	120,063	10,424
Unearned premiums	116,627	113,483
Other	(243,221)	(177,805)
Net cash (used in) from operating activities	(20,035)	75,472
CASH USED IN INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	2,004,008	719,969
Proceeds from sale of equity securities	152,949	51,854
Distributions from (contributions to) investment funds	33,695	(11,290)
Proceeds from maturities and prepayments of fixed maturity securities	97,911	888,423
Purchase of fixed maturity securities	(2,085,683)	(1,767,208)
Purchase of equity securities	(44,219)	(103)
Real estate purchased	(336,601)	(48,710)
Change in loans receivable	2,058	3,147
Net additions to property, furniture and equipment	(14,102)	(12,457)
Change in balances due to security brokers	58,500	(22,034)
Payment for business purchased net of cash acquired	0	(71,346)
Net cash used in investing activities	(131,484)	(269,755)
CASH FROM (USED IN) FINANCING ACTIVITIES:
Repayment of senior notes and other debt	(23)	(1,475)
Net proceeds from issuance of debt	181,792	0
Cash dividends to common stockholders	(17,016)	0
Purchase of common treasury shares	(6,799)	0
Other, net	(544)	(1,281)
Net cash from (used in) financing activities	157,410	(2,756)
Net impact on cash due to change in foreign exchange rates	241	10,147
Net change in cash and cash equivalents	6,132	(186,892)
Cash and cash equivalents at beginning of year	950,471	795,285
Cash and cash equivalents at end of period	$ 956,603	$ 608,393