Financial Instruments Measured at Fair Value - Fair Value Hierarchy (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Mar. 29, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 70,910	$ 69,857
Foreign exchange contracts	1,003	(654)
Contingent consideration	(11,606)	(5,845)
Total Fair Value Assets And Liabilities Measured On Recurring Basis	60,307	63,358
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	70,910	69,857
Foreign exchange contracts	0	0
Contingent consideration	0	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis	70,910	69,857
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Foreign exchange contracts	1,003	(654)
Contingent consideration	0	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis	1,003	(654)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities	0	0
Foreign exchange contracts	0	0
Contingent consideration	(11,606)	(5,845)
Total Fair Value Assets And Liabilities Measured On Recurring Basis	$ (11,606)	$ (5,845)