Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
CASH FROM OPERATING ACTIVITIES:
Net income to common stockholders	$ 728,060	$ 218,520
Adjustments to reconcile net income to net cash from operating activities:
Net investment (gains) losses	(78,404)	60,311
Depreciation and amortization	101,330	96,195
Noncontrolling interests	8,652	1,975
Investment funds	(169,538)	(1,260)
Stock incentive plans	36,486	37,842
Change in:
Arbitrage trading account	(224,613)	(40,487)
Premiums and fees receivable	(365,092)	(175,636)
Reinsurance accounts	(255,126)	(204,396)
Deferred policy acquisition costs	(108,131)	(43,955)
Income taxes	(81,574)	(56,955)
Reserves for losses and loss expenses	1,164,594	879,277
Unearned premiums	707,658	407,227
Other	60,092	(41,713)
Net cash from operating activities	1,524,394	1,136,945
CASH (USED IN) FROM INVESTING ACTIVITIES:
Proceeds from sale of fixed maturity securities	1,631,849	3,525,926
Proceeds from sale of equity securities	100,366	66,850
Distributions from investment funds	124,892	83,935
Proceeds from maturities and prepayments of fixed maturity securities	4,672,562	2,876,642
Purchase of fixed maturity securities	(8,442,260)	(6,074,429)
Purchase of equity securities	(340,424)	(77,840)
Real estate sold (purchased)	182,998	(42,405)
Change in loans receivable	(27,764)	1,202
Net purchases of property, furniture and equipment	(53,558)	(31,047)
Change in balances due to security brokers	110,752	36,561
Other	14	65
Net cash (used in) from investing activities	(2,040,573)	365,460
CASH FROM FINANCING ACTIVITIES:
Repayment of senior notes and other debt	(503,914)	(302,453)
Net proceeds from issuance of debt	1,032,404	747,399
Cash dividends to common stockholders	(156,107)	(62,822)
Purchase of common treasury shares	(122,426)	(311,859)
Other, net	(27,941)	(18,465)
Net cash from financing activities	222,016	51,800
Net impact on cash due to change in foreign exchange rates	(9,174)	(6,468)
Net change in cash and cash equivalents	(303,337)	1,547,737
Cash and cash equivalents at beginning of period	2,372,366	1,023,710
Cash and cash equivalents at end of period	$ 2,069,029	$ 2,571,447