Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities
Net earnings	$ 854,027	$ 759,045
Adjustments to reconcile net earnings to net cash provided by (used in) operating activities:
Depreciation and amortization	84,943	95,427
Change in the fair value of equity securities	(519,322)	(512,771)
Net realized capital (gains) losses	(20,753)	(67,197)
Other than temporary impairment losses	13,617	514
(Increase) decrease in reinsurance recoverables, net of reinsurance payable	318,475	(18,104)
(Increase) decrease in premium balances receivable	(86,098)	(41,671)
(Increase) decrease in ceded unearned premiums	(37,385)	(38,207)
(Increase) decrease in deferred acquisition costs	(41,280)	(17,936)
(Increase) decrease in funds held under reinsurance agreements	3,766	(49,692)
Increase (decrease) in unearned premiums	228,620	118,494
Increase (decrease) in loss and loss adjustment expenses	(616,273)	(16,391)
Change in unrealized foreign currency exchange rate losses (gains)	41,427	63,452
Other, net	204,484	48,819
Net adjustments	(425,779)	(435,263)
Net cash provided by (used in) operating activities	428,248	323,782
Cash flows from investing activities
Purchases of debt securities	(5,648,309)	(3,206,369)
Purchases of equity securities	(265,647)	(678,311)
Sales of debt securities	2,649,257	2,279,104
Maturities and redemptions of debt securities	807,977	1,183,469
Sales of equity securities	2,261,863	532,864
Net (purchases) sales of short-term investments	(69,908)	(113,699)
Net (purchases) sales and maturities of commercial mortgage loans	(29,498)	(37,525)
(Purchases) sales of property and equipment	(35,481)	(38,866)
Purchases of affiliates and subsidiaries, net of cash acquired	(85,132)	(110,636)
Other, net	(33,604)	59,382
Net cash provided by (used in) investing activities	(448,482)	(130,587)
Cash flows from financing activities
Treasury stock acquisitions	(112,446)	(282,053)
Increase (decrease) in other debt	26,605	50,892
Cash dividends paid		(153,967)
Other, net	(36,991)	7,854
Net cash provided by (used in) financing activities	(122,832)	(377,274)
Effect of foreign exchange rate changes on cash	1,780	(7,388)
Net increase (decrease) in cash	(141,286)	(191,467)
Cash at beginning of period	1,038,763	838,375
Cash at end of period	897,477	646,908
Supplemental disclosures of cash flow information
Interest paid	69,029	59,806
Income taxes paid (refund received)	$ 66,325	$ 33,332