Financial Instruments Measured at Fair Value - Fair Value Hierarchy (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Mar. 28, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		$ 99,000
Available-for-sale securities	38,946	38,109
Interest rate swaps	1,353	378
Foreign exchange contracts	588	694
Contingent consideration	(3,361)	(6,202)
Total Fair Value Assets And Liabilities Measured On Recurring Basis	37,526	131,979
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents		99,000
Available-for-sale securities	38,946	38,109
Interest rate swaps	0	0
Foreign exchange contracts	0	0
Contingent consideration	0	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis	38,946	137,109
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	1,353	378
Foreign exchange contracts	588	694
Contingent consideration	0	0
Total Fair Value Assets And Liabilities Measured On Recurring Basis	1,941	1,072
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	0
Foreign exchange contracts	0	0
Contingent consideration	(3,361)	(6,202)
Total Fair Value Assets And Liabilities Measured On Recurring Basis	$ (3,361)	$ (6,202)