Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net earnings (losses)	$ 238,063	$ (361,472)
Adjustments to reconcile net earnings to net cash provided by (used in) operating activities:
Depreciation and amortization	43,554	33,158
Change in the fair value of equity securities	(112,728)	522,976
Net realized capital (gains) losses	(12,931)	(13,026)
Change in allowance for credit losses on available for sale securities	(1,972)	31,375
(Increase) decrease in reinsurance recoverables, net of reinsurance payable	(6,669)	49,693
(Increase) decrease in premium balances receivable	(138,822)	(143,970)
(Increase) decrease in ceded unearned premiums	(34,049)	(18,020)
(Increase) decrease in deferred acquisition costs	(41,969)	(18,463)
(Increase) decrease in funds held under reinsurance agreements	8,951	(23,757)
Increase (decrease) in unearned premiums	192,735	102,239
Increase (decrease) in loss and loss adjustment expenses	322,420	138,079
Change in unrealized foreign currency exchange rate losses (gains)	44,344	80,530
Other, net	(58,632)	(386,627)
Net adjustments	204,232	354,187
Net cash provided by (used in) operating activities	442,295	(7,285)
Cash flows from investing activities
Purchases of debt securities	(1,401,010)	(1,993,449)
Purchases of equity securities	(746,350)	(331,453)
Sales of debt securities	1,197,630	1,960,691
Maturities and redemptions of debt securities	552,933	459,655
Sales of equity securities	262,690	602,627
Net (purchases) sales of short-term investments	117,295	378,854
Net (purchases) sales and maturities of commercial mortgage loans	30,618	3,551
(Purchases) sales of property and equipment	(12,322)	(8,840)
Purchases of affiliates and subsidiaries, net of cash acquired		(26,383)
Other, net	101,159	(152,416)
Net cash provided by (used in) investing activities	102,643	892,837
Cash flows from financing activities
Repayment of senior notes		(307,095)
Treasury stock acquisitions	(63,192)	(44,268)
Increase (decrease) in other debt	(55,729)	62,659
Cash dividends paid		(215,013)
Other, net	(8,938)	3,664
Net cash provided by (used in) financing activities	(127,859)	(500,053)
Effect of foreign exchange rate changes on cash	(11,047)	(9,412)
Net increase (decrease) in cash	406,032	376,087
Cash at beginning of period	791,442	1,179,098
Cash at end of period	1,197,474	1,555,185
Supplemental disclosures of cash flow information
Interest paid	10,000	17,065
Income taxes paid (refund received)	$ 22,599	$ 24,604