Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Cash received from customers	$ 1,160,904	$ 999,779
Cash paid to suppliers and employees	(1,007,565)	(968,719)
Interest paid, net	(11,277)	(10,865)
Income tax payments, net	(47,620)	(19,066)
Investment proceeds and miscellaneous receipts, net	18,354	13,197
Proceeds from (payments for) forward foreign exchange contracts, net	5,412	(8,029)
Net cash provided by operating activities	118,208	6,297
Cash flows from investing activities:
Capital expenditures	(53,897)	(64,951)
Proceeds from dispositions of property, plant and equipment	4,100	21
Proceeds from divestiture of a product line	6,919	0
Proceeds from (payments for) acquisitions	266
Payments for acquisitions and long-term investments		(73,573)
Payments for purchases of intangible assets	(3)	(3,920)
Payments for purchases of marketable securities and investments	(183,001)	(142,993)
Proceeds from Sale of Debt Securities, Available-for-sale	34,548
Proceeds from sales of marketable securities and investments		39,362
Proceeds from maturities of marketable securities and investments	88,410	98,379
Net cash used in investing activities	(102,658)	(147,675)
Cash flows from financing activities:
Net payments on line-of-credit arrangements and notes payable	0	(36)
Payments on long-term borrowings	(1,505)	(149)
Payments of contingent consideration	(1,270)	(3,105)
Proceeds from issuance of common stock for shared-based compensation	3,274	3,778
Payments for purchases of treasury stock	0	(883)
Net cash provided by (used in) financing activities	499	(395)
Effect of foreign exchange rate changes on cash	3,053	7,190
Net increase (decrease) in cash, cash equivalents, and restricted cash	19,102	(134,583)
Beginning Cash, Cash Equivalents, and Restricted Cash	384,983	457,171
Cash and cash equivalents	403,006	321,584
Restricted Cash, Current	105	561
Restricted Cash, Noncurrent	974	443
Ending Cash, Cash Equivalents, and Restricted Cash	$ 404,085	$ 322,588