Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FROM OPERATING ACTIVITIES:
Net income (loss) to common stockholders	$ 229,525	$ (4,418)
Adjustments to reconcile net income (loss) to net cash from operating activities:
Net investment (gains) losses	(34,839)	177,174
Depreciation and amortization	33,543	25,063
Noncontrolling interests	2,191	892
Investment funds	(38,935)	(40,576)
Stock incentive plans	11,817	11,683
Change in:
Arbitrage trading account	(16,108)	2,455
Premiums and fees receivable	(96,290)	(97,169)
Reinsurance accounts	(105,589)	(43,104)
Deferred policy acquisition costs	(38,577)	(26,139)
Income taxes	47,372	(12,500)
Reserves for losses and loss expenses	303,305	200,294
Unearned premiums	219,920	163,793
Other	(206,345)	(204,878)
Net cash from operating activities	310,990	152,570
CASH (USED IN) FROM INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	1,115,114	1,574,232
Proceeds from sale of equity securities	57,457	5,311
Distributions from investment funds	36,236	99,194
Proceeds from maturities and prepayments of fixed maturity securities	1,623,357	1,055,722
Purchase of fixed maturity securities	(4,118,161)	(2,598,076)
Purchase of equity securities	(69,181)	(35,260)
Real estate sold (purchased)	9,787	(24,249)
Change in loans receivable	9,256	2,877
Net purchases of property, furniture and equipment	(10,872)	(14,637)
Change in balances due to security brokers	151,776	(34,378)
Other	0	86
Net cash (used in) from investing activities	(1,195,231)	30,822
CASH FROM (USED IN) FINANCING ACTIVITIES:
Repayment of senior notes and other debt	(110,000)	0
Net payments for stock options exercised	(525)	(3,321)
Net proceeds from issuance of debt	691,213	4,259
Cash dividends to common stockholders	(21,285)	(20,069)
Purchase of common treasury shares	(29,683)	(202,621)
Other, net	(1,503)	(204)
Net cash from (used in) financing activities	528,217	(221,956)
Net impact on cash due to change in foreign exchange rates	(1,431)	(20,134)
Net change in cash and cash equivalents	(357,455)	(58,698)
Cash and cash equivalents at beginning of year	2,372,366	1,023,710
Cash and cash equivalents at end of period	$ 2,014,911	$ 965,012