Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net earnings	$ 171,182	$ 149,360
Adjustments to reconcile net earnings to net cash provided by (used in) operating activities:
Depreciation and amortization	33,107	35,663
Change in the fair value of equity securities	42,649
Net realized capital (gains) losses	(44,505)	(59,651)
Other than temporary impairment losses	511	3,217
(Increase) decrease in reinsurance recoverables, net of reinsurance payable	96,582	34,196
(Increase) decrease in premium balances receivable	(58,732)	(62,971)
(Increase) decrease in ceded unearned premiums	(14,388)	(17,874)
(Increase) decrease in deferred acquisition costs	(14,178)	(6,488)
(Increase) decrease in funds held under reinsurance agreements	609	(23,885)
Increase (decrease) in unearned premiums	69,299	39,448
Increase (decrease) in loss and loss adjustment expenses	(156,981)	(97,254)
Change in unrealized foreign exchange losses (gains)	(35,143)	(19,971)
Other, net	(95,181)	(16,322)
Net adjustments	(176,351)	(191,892)
Net cash provided by (used in) operating activities	(5,169)	(42,532)
Cash flows from investing activities
Purchases of debt securities	(989,813)	(1,811,566)
Purchases of equity securities	(451,519)	(304,343)
Sales of debt securities	1,014,024	1,349,608
Maturities and redemptions of debt securities	466,457	443,960
Sales of equity securities	172,819	1,363,269
Net (purchases) sales of short-term investments	(33,634)	(949,847)
Net (purchases) sales and maturities of commercial mortgage loans	(5,569)	(24,803)
(Purchases) sales of property and equipment	(11,057)	(4,480)
Purchases of affiliates and subsidiaries, net of cash acquired	(105,386)
Other, net	(23,951)	29,388
Net cash provided by (used in) investing activities	32,371	91,186
Cash flows from financing activities
Treasury stock acquisitions	(21,268)
Increase (decrease) in other debt	9,957	(5,509)
Cash dividends paid	(153,967)
Other, net	4,654	(13,057)
Net cash provided by (used in) financing activities	(160,624)	(18,566)
Effect of exchange rate changes on cash	6,087	266
Net increase (decrease) in cash	(127,335)	30,354
Cash at beginning of period	838,375	594,091
Cash at end of period	711,040	624,445
Cash paid during period for:
Interest paid	16,942	16,359
Income taxes paid (refund received)	$ 20,275	$ 5,949