Financial Instruments Measured at Fair Value - Fair Value Hierarchy (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 29, 2018		Sep. 29, 2018		Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Gain on Securities		$ 222
Unrealized Loss on Securities				$ 6,908
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents		17,501		17,501		$ 289,938	[1]
Equity investments		44,068		44,068		52,683
Interest rate swaps- liability		(864)		(864)		(149)
Foreign exchange contracts - asset		3,248		3,248		5,499
Foreign exchange contracts - liability		(2,955)		(2,955)		(8,581)
Contingent consideration						(3,176)
Total Fair Value Assets And Liabilities Measured On Recurring Basis		60,998		60,998		336,214
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents		17,501	[2]	17,501	[2]	3,267
Equity investments	[3]	44,068		44,068		52,683
Interest rate swaps- liability		0		0		0
Foreign exchange contracts - asset		0		0		0
Foreign exchange contracts - liability		0		0		0
Contingent consideration						0
Total Fair Value Assets And Liabilities Measured On Recurring Basis		61,569		61,569		55,950
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents		0		0		286,671	[1]
Equity investments		0		0		0
Interest rate swaps- liability		(864)		(864)		(149)
Foreign exchange contracts - asset		3,248		3,248		5,499
Foreign exchange contracts - liability		(2,955)		(2,955)		(8,581)
Contingent consideration						0
Total Fair Value Assets And Liabilities Measured On Recurring Basis		(571)		(571)		283,440
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents		0		0		0
Equity investments		0		0		0
Interest rate swaps- liability		0		0		0
Foreign exchange contracts - asset		0		0		0
Foreign exchange contracts - liability		0		0		0
Contingent consideration						(3,176)
Total Fair Value Assets And Liabilities Measured On Recurring Basis		$ 0		$ 0		$ (3,176)
Marubun [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Ownership Percentage		8.40%		8.40%

[1] Cash equivalents at December 31, 2017 included $286,671 invested in certificates of deposit, with an original maturity of less than three months, held in anticipation of our acquisition of eInfochips, which closed in January 2018 (see Note D).

[2] Cash equivalents include highly liquid investments with an original maturity of less than three months.

[3] The company has an 8.4% equity ownership interest in Marubun Corporation and a portfolio of mutual funds with quoted market prices. The company recorded an unrealized gain of $222 and an unrealized loss of $6,908 for the third quarter and first nine months of 2018, respectively, on equity securities held at September 29, 2018