Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CASH FROM OPERATING ACTIVITIES:
Net income to common stockholders	$ 1,381,062	$ 1,022,490	$ 530,670
Adjustments to reconcile net income to net cash from operating activities:
Net investment gains	(202,397)	(90,632)	(103,000)
Depreciation and amortization	55,872	129,682	135,065
Noncontrolling interests	3,892	8,525	2,315
Investment funds	(145,099)	(220,015)	(54,253)
Stock incentive plans	49,411	46,680	49,658
Change in:
Arbitrage trading account	(53,291)	(268,649)	(67,943)
Premiums and fees receivable	(268,171)	(364,395)	(173,618)
Reinsurance accounts	(266,307)	(433,644)	(313,525)
Deferred policy acquisition costs	(88,844)	(121,663)	(38,691)
Current income taxes	(3,534)	(43,890)	49,021
Deferred income taxes	(64,712)	7,630	(34,057)
Reserves for losses and loss expenses	1,684,254	1,635,774	1,176,049
Unearned premiums	466,590	786,627	415,956
Other	19,878	89,467	43,039
Net cash from operating activities	2,568,604	2,183,987	1,616,686
CASH FLOWS (USED IN) FROM INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	797,948	1,842,139	3,832,555
Proceeds from sale of equity securities	82,319	126,980	114,763
Distributions from (contributions to) investment funds	(24,623)	(101,050)	3,042
Proceeds from maturities and prepayments of fixed maturity securities	4,891,179	6,067,230	3,864,327
Purchase of fixed maturity securities	(8,036,680)	(10,716,748)	(7,551,591)
Purchase of equity securities	(340,482)	(464,645)	(253,031)
Real estate (purchased) sold	(45,920)	166,886	178,934
Change in loans receivable	(83,212)	(27,421)	1,467
Net additions to property, furniture and equipment	(52,684)	(66,634)	(38,171)
Change in balances due from security brokers	14,337	(17,983)	(26,515)
Cash received in connection with business disposition	906,789	0	0
Payment for business purchased, net of cash acquired	(49,572)	0	0
Net cash (used in) from investing activities	(1,891,355)	(2,989,146)	119,696
CASH FLOWS (USED IN) FROM FINANCING ACTIVITIES:
Net (payments) proceeds from issuance of debt	(3,309)
Net (payments) proceeds from issuance of debt		1,034,107	741,637
Repayment of senior notes and other debt	(426,503)	(504,952)	(652,751)
Cash dividends to common stockholders	(235,192)	(355,736)	(84,147)
Purchase of common treasury shares	(94,140)	(122,426)	(346,357)
Other, net	(12,848)	(45,162)	(56,225)
Net cash (used in) from financing activities	(771,992)	5,831	(397,843)
Net impact on cash due to change in foreign exchange rates	(24,754)	(4,195)	10,117
Net (decrease) increase in cash and cash equivalents	(119,497)	(803,523)	1,348,656
Cash and cash equivalents at beginning of year	1,568,843	2,372,366	1,023,710
Cash and cash equivalents at end of year	$ 1,449,346	$ 1,568,843	$ 2,372,366