Financial Instruments Measured at Fair Value - Fair Value Hierarchy (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Jul. 01, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	$ 893	$ 2,660
Available-for-sale securities	43,481	37,915
Interest rate swaps - asset	300	152
Foreign exchange contracts - asset	6,490	4,685
Foreign exchange contracts - liability	(8,714)	(3,444)
Contingent consideration	(2,959)	(4,027)
Total Fair Value Assets And Liabilities Measured On Recurring Basis	39,491	37,941
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	893	2,660
Available-for-sale securities	43,481	37,915
Interest rate swaps - asset	0	0
Foreign exchange contracts - asset	0	0
Foreign exchange contracts - liability	0	0
Contingent consideration	0	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis	44,374	40,575
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	0	0
Available-for-sale securities	0	0
Interest rate swaps - asset	300	152
Foreign exchange contracts - asset	6,490	4,685
Foreign exchange contracts - liability	(8,714)	(3,444)
Contingent consideration	0	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis	(1,924)	1,393
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	0	0
Available-for-sale securities	0	0
Interest rate swaps - asset	0	0
Foreign exchange contracts - asset	0	0
Foreign exchange contracts - liability	0	0
Contingent consideration	(2,959)	(4,027)
Total Fair Value Assets And Liabilities Measured On Recurring Basis	$ (2,959)	$ (4,027)