Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Cash received from customers	$ 1,716,486	$ 1,715,960
Cash paid to suppliers and employees	(1,392,653)	(1,494,794)
Interest paid, net	(11,381)	(11,721)
Income tax payments, net	(42,634)	(57,840)
Investment proceeds and miscellaneous receipts, net	28,092	21,601
Proceeds from forward foreign exchange contracts, net	185	7,279
Net cash provided by operating activities	298,095	180,485
Cash flows from investing activities:
Capital expenditures	(76,934)	(75,951)
Proceeds from dispositions of property, plant and equipment	85	4,273
Proceeds from divestiture of a product line	0	6,964
(Payments for) proceeds from acquisitions, net of cash received	(75,811)	266
Recovery of (payments for) purchases of intangible assets	7,383	(3)
Payments for purchases of marketable securities and investments	(266,839)	(286,826)
Proceeds from sales of marketable securities and investments	83,315	60,488
Proceeds from maturities of marketable securities and investments	181,108	158,622
Net cash used in investing activities	(147,693)	(132,167)
Cash flows from financing activities:
Payments on long-term borrowings	(487)	(1,595)
Payments for credit agreement renewal fees	(486)	0
Payments of contingent consideration	(2,477)	(2,078)
Proceeds from Issuance of Common Stock	9,740	10,858
Tax payments from net share settlement	(8,096)	(8,862)
Proceeds from reissuances of treasury stock for share-based compensation, net	3,831	0
Payments for purchases of treasury stock	(20,000)	0
Net cash used in financing activities	(17,975)	(1,677)
Effect of foreign exchange rate changes on cash	(3,239)	3,965
Net increase in cash, cash equivalents, and restricted cash	129,188	50,606
Beginning Cash, Cash Equivalents, and Restricted Cash	434,164	384,983
Cash and cash equivalents	561,071	434,517
Restricted Cash, Current	100	102
Restricted Cash, Noncurrent	2,181	970
Ending Cash, Cash Equivalents, and Restricted Cash	$ 563,352	$ 435,589