Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Cash received from customers	$ 1,127,141	$ 1,143,222
Cash paid to suppliers and employees	(959,300)	(932,009)
Interest paid, net	(10,847)	(11,085)
Income tax payments, net	(10,005)	(24,016)
Investment proceeds and miscellaneous receipts, net	6,092	24,093
Proceeds from forward foreign exchange contracts, net	1,849	(1,860)
Net cash provided by operating activities	154,930	198,345
Cash flows from investing activities:
Capital expenditures	(39,707)	(45,843)
Proceeds from dispositions of property, plant and equipment	33	86
Payments for purchases of marketable securities and investments	(172,663)	(171,615)
Proceeds from maturities of marketable securities and investments	133,197	138,244
Proceeds from Sale of Debt Securities, Available-for-sale	62,894	50,044
Payments for Acquisitions, net of cash received	(96,889)	(16,083)
(Payments for) recovery of purchases of intangible assets	(100)	7,383
Proceeds from Divestiture of Businesses	12,240	0
Net cash used in investing activities	(100,995)	(37,784)
Cash flows from financing activities:
Payments on long-term borrowings	(1,597)	(359)
Payments for credit agreement renewal fees	0	(458)
Payments of contingent consideration	(1,265)	(1,433)
Proceeds from Issuance of Common Stock	8,202	3,912
Tax payments from net share settlement	(6,931)	(3,976)
Proceeds from Reissuance of Treasury Stock	0	3,831
Payments for purchases of treasury stock	(100,005)	(15,001)
Net cash used in financing activities	(101,596)	(13,484)
Effect of Exchange Rate on Cash and Cash Equivalents	(2,858)	2,127
Beginning Cash, Cash Equivalents, and Restricted Cash	662,651	434,164
Cash and cash equivalents	607,584	580,684
Ending Cash, Cash Equivalents, and Restricted Cash	612,132	583,368
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect	(50,519)	149,204
Other Current Assets
Cash flows from financing activities:
Restricted Cash, Current	3,575	114
Other Assets
Cash flows from financing activities:
Restricted Cash, Noncurrent	$ 973	$ 2,570