Financial Instruments Measured at Fair Value - Fair Value Hierarchy (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Jun. 28, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	$ 25,000
Available-for-sale securities	79,302	69,857
Interest rate swaps	270
Foreign exchange contracts	(495)	(654)
Contingent consideration	(12,698)	(5,845)
Total Fair Value Assets And Liabilities Measured On Recurring Basis	91,379	63,358
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	25,000
Available-for-sale securities	79,302	69,857
Interest rate swaps	0
Foreign exchange contracts	0	0
Contingent consideration	0	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis	104,302	69,857
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	0
Available-for-sale securities	0	0
Interest rate swaps	270
Foreign exchange contracts	(495)	(654)
Contingent consideration	0	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis	(225)	(654)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents	0
Available-for-sale securities	0	0
Interest rate swaps	0
Foreign exchange contracts	0	0
Contingent consideration	(12,698)	(5,845)
Total Fair Value Assets And Liabilities Measured On Recurring Basis	$ (12,698)	$ (5,845)