Financial Instruments Measured at Fair Value - Fair Value Hierarchy (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Gain on Securities		$ 1,824
Unrealized Loss on Securities		2,579
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents		21,738	$ 22,883
Equity investments		42,753	38,045
Interest rate swaps- liability		(557)	(589)
Foreign exchange contracts - asset		12,925	4,163
Foreign exchange contracts - liability		(998)	(2,384)
Total Fair Value Assets And Liabilities Measured On Recurring Basis		75,861	62,118
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	[1]	21,738	22,883
Equity investments	[2]	42,753	38,045
Interest rate swaps- liability		0	0
Foreign exchange contracts - asset		0	0
Foreign exchange contracts - liability		0	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis		64,491	60,928
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
Equity investments		0	0
Interest rate swaps- liability		(557)	(589)
Foreign exchange contracts - asset		12,925	4,163
Foreign exchange contracts - liability		(998)	(2,384)
Total Fair Value Assets And Liabilities Measured On Recurring Basis		11,370	1,190
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
Equity investments		0	0
Interest rate swaps- liability		0	0
Foreign exchange contracts - asset		0	0
Foreign exchange contracts - liability		0	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis		$ 0	$ 0
Marubun [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment Ownership Percentage		8.40%

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

[2] 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 $1,824 and an unrealized loss of $2,579 for the first quarter of 2019 and 2018, respectively, on equity securities held at the end of each quarter.