Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net earnings	$ 469,586	$ 252,019
Adjustments to reconcile net earnings to net cash provided by (used in) operating activities:
Depreciation and amortization	64,510	69,723
Change in the fair value of equity securities	(142,596)
Net realized capital (gains) losses	(50,967)	(68,919)
Other than temporary impairment losses		6,964
Other than temporary impairment losses	511
(Increase) decrease in reinsurance recoverables, net of reinsurance payable	147,456	109,287
(Increase) decrease in premium balances receivable	(34,643)	(109,073)
(Increase) decrease in ceded unearned premiums	(18,282)	4,057
(Increase) decrease in deferred acquisition costs	(14,897)	(20,683)
(Increase) decrease in funds held under reinsurance agreements	(13,318)	(50,281)
Increase (decrease) in unearned premiums	97,516	78,592
Increase (decrease) in loss and loss adjustment expenses	(355,757)	(26,960)
Change in unrealized foreign currency exchange rate losses (gains)	48,228	(86,834)
Other, net	(48,172)	45,989
Net adjustments	(320,411)	(48,138)
Net cash provided by (used in) operating activities	149,175	203,881
Cash flows from investing activities
Purchases of debt securities	(2,301,614)	(3,313,484)
Purchases of equity securities		(1,849,990)
Purchase of equity securities	(533,842)
Sales of debt securities	1,667,526	2,193,147
Maturities and redemptions of debt securities	886,970	907,309
Sales of equity securities		1,972,117
Sales of equity securities	269,567
Net (purchases) sales of short-term investments	104,728	73,725
Net (purchases) sales and maturities of commercial mortgage loans	(37,408)	(41,659)
(Purchases) sales of property and equipment	(13,164)	16,006
Purchases of affiliates and subsidiaries, net of cash acquired	(108,386)	(164,528)
Other, net	50,415	84,585
Net cash provided by (used in) investing activities	(15,208)	(122,772)
Cash flows from financing activities
Treasury stock acquisitions	(236,103)
Increase (decrease) in other debt	38,452	(26,098)
Cash dividends paid	(153,967)
Other, net	5,317	(15,238)
Net cash provided by (used in) financing activities	(346,301)	(41,336)
Effect of foreign currency exchange rate changes on cash	(2,818)	9,821
Net increase (decrease) in cash	(215,152)	49,594
Cash at beginning of period	838,375	594,091
Cash at end of period	623,223	643,685
Cash paid during period for:
Interest paid	42,562	41,207
Income taxes paid (refund received)	$ 22,135	$ 31,242