Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities
Net earnings	$ 752,735	$ 469,586
Adjustments to reconcile net earnings to net cash provided by (used in) operating activities:
Depreciation and amortization	56,942	64,510
Change in the fair value of equity securities	(536,013)	(142,596)
Net realized capital (gains) losses	(16,796)	(50,967)
Other than temporary impairment losses	10,020	511
(Increase) decrease in reinsurance recoverables, net of reinsurance payable	271,113	147,456
(Increase) decrease in premium balances receivable	(122,872)	(34,643)
(Increase) decrease in ceded unearned premiums	(22,084)	(18,282)
(Increase) decrease in deferred acquisition costs	(38,099)	(14,897)
(Increase) decrease in funds held under reinsurance agreements	14,471	(13,318)
Increase (decrease) in unearned premiums	197,072	97,516
Increase (decrease) in loss and loss adjustment expenses	(618,496)	(355,757)
Change in unrealized foreign currency exchange rate losses (gains)	(6,370)	48,228
Other, net	231,955	(48,172)
Net adjustments	(579,157)	(320,411)
Net cash provided by (used in) operating activities	173,578	149,175
Cash flows from investing activities
Purchases of debt securities	(4,197,740)	(2,301,614)
Purchases of equity securities	(134,894)	(533,842)
Sales of debt securities	1,876,234	1,667,526
Maturities and redemptions of debt securities	443,555	886,970
Sales of equity securities	1,950,478	269,567
Net (purchases) sales of short-term investments	(156,700)	104,728
Net (purchases) sales and maturities of commercial mortgage loans	(14,905)	(37,408)
(Purchases) sales of property and equipment	(23,942)	(13,164)
Purchases of affiliates and subsidiaries, net of cash acquired	(64,084)	(108,386)
Other, net	8,842	50,415
Net cash provided by (used in) investing activities	(313,156)	(15,208)
Cash flows from financing activities
Treasury stock acquisitions	(93,152)	(236,103)
Increase (decrease) in other debt	46,006	38,452
Cash dividends paid		(153,967)
Other, net	(31,344)	5,317
Net cash provided by (used in) financing activities	(78,490)	(346,301)
Effect of foreign exchange rate changes on cash	4,123	(2,818)
Net increase (decrease) in cash	(213,945)	(215,152)
Cash at beginning of period	1,038,763	838,375
Cash at end of period	824,818	623,223
Supplemental disclosures of cash flow information
Interest paid	48,203	42,562
Income taxes paid (refund received)	$ (20,672)	$ 22,135