Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Cash received from customers	$ 2,074,024	$ 1,956,084	$ 2,162,520
Cash paid to suppliers and employees	(1,810,844)	(1,730,062)	(1,806,526)
Interest paid	(21,318)	(20,793)	(20,793)
Income tax payments	(38,442)	(31,715)	(28,939)
Settlement with the SEC and DOJ relating to the FCPA, including interest	0	0	(55,050)
Investment proceeds and miscellaneous receipts, net	15,683	11,953	15,671
Excess tax benefits from share-based compensation	(1,506)	(3,610)	(1,349)
(Payments for) proceeds from forward foreign exchange contracts, net	(1,164)	4,353	7,778
Net cash provided by operating activities	216,433	186,210	273,312
Cash flows from investing activities:
Capital expenditures	(141,436)	(112,000)	(120,999)
Proceeds from dispositions of property, plant and equipment	398	79	225
Payments for acquisitions, net of cash received, and long-term investments	(14,165)	(4,356)	(44,627)
Payments for purchases of intangible assets	(135)	(1,372)	(15,479)
Payments for purchases of restricted investment	(350)	(4,210)	0
Payments for purchases of marketable securities and investments	(278,071)	(294,497)	(205,746)
Proceeds from sales of marketable securities and investments	76,859	78,664	75,725
Proceeds from maturities of marketable securities and investments	143,020	170,823	120,390
Net cash used in investing activities	(213,880)	(166,869)	(190,511)
Cash flows from financing activities:
Net borrowings on (payments for) line-of-credit arrangements and notes payable	37	0	(1,560)
Payments on long-term borrowings	(303)	(282)	(253)
Proceeds from issuance of common stock	11,280	8,236	15,051
Payments of contingent consideration	(3,500)	(2,983)	(2,374)
Debt issuance costs on long-term borrowings	0	0	(524)
Excess tax benefits from share-based compensation	1,506	3,610	1,349
Net cash provided by financing activities	9,020	8,581	11,689
Effect of foreign exchange rate changes on cash	(12,858)	16,376	(12,790)
Net (decrease) increase in cash and cash equivalents	(1,285)	44,298	81,700
Cash and cash equivalents at beginning of year	457,549	413,251	331,551
Cash and cash equivalents at end of year	$ 456,264	$ 457,549	$ 413,251