Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FROM OPERATING ACTIVITIES:
Net income to common stockholders	$ 1,022,490	$ 530,670	$ 681,944
Adjustments to reconcile net income to net cash from operating activities:
Net investment gains	(90,632)	(103,000)	(120,703)
Depreciation and amortization	129,682	135,065	113,387
Noncontrolling interests	8,525	2,315	2,041
Investment funds	(220,015)	(54,253)	(69,194)
Stock incentive plans	46,680	49,658	49,274
Change in:
Arbitrage trading account	(268,649)	(67,943)	(26,553)
Premiums and fees receivable	(364,395)	(173,618)	(189,151)
Reinsurance accounts	(433,644)	(313,525)	(165,898)
Deferred policy acquisition costs	(121,663)	(38,691)	(20,057)
Current income taxes	(43,890)	49,021	(12,530)
Deferred income taxes	7,630	(34,057)	7,130
Reserves for losses and loss expenses	1,635,774	1,176,049	612,254
Unearned premiums	786,627	415,956	301,355
Other	89,467	43,039	(19,506)
Net cash from operating activities	2,183,987	1,616,686	1,143,793
CASH FLOWS (USED IN) FROM INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	1,842,139	3,832,555	2,093,271
Proceeds from sale of equity securities	126,980	114,763	79,963
Distributions from (contributions to) investment funds	(101,050)	3,042	(194,663)
Proceeds from maturities and prepayments of fixed maturity securities	6,067,230	3,864,327	2,933,980
Purchase of fixed maturity securities	(10,716,748)	(7,551,591)	(5,352,886)
Purchase of equity securities	(464,645)	(253,031)	(172,978)
Real estate sold (purchased)	166,886	178,934	(146,752)
Change in loans receivable	(27,421)	1,467	3,481
Net additions to property, furniture and equipment	(66,634)	(38,171)	(60,457)
Change in balances due from security brokers	(17,983)	(26,515)	2,844
Net cash (used in) from investing activities	(2,989,146)	119,696	(424,871)
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES:
Net proceeds from issuance of debt	1,034,107	741,637	290,974
Repayment and redemption of debt	(504,952)	(652,751)	(456,360)
Cash dividends to common stockholders	(355,736)	(84,147)	(308,191)
Purchase of common treasury shares	(122,426)	(346,357)	(18,225)
Other, net	(45,162)	(56,225)	(21,391)
Net cash from (used in) financing activities	5,831	(397,843)	(513,193)
Net impact on cash due to change in foreign exchange rates	(4,195)	10,117	379
Net (decrease) increase in cash and cash equivalents	(803,523)	1,348,656	206,108
Cash and cash equivalents at beginning of year	2,372,366	1,023,710	817,602
Cash and cash equivalents at end of year	$ 1,568,843	$ 2,372,366	$ 1,023,710