Financial Instruments Measured at Fair Value - Unobservable Inputs Reconciliation (Details) (Fair Value, Inputs, Level 3 [Member], Fair Value, Measurements, Recurring [Member], Contingent Consideration [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 28, 2015
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Contingent Consideration [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance as of December 31, 2014	$ (6,202)
Fair value of initial contingent consideration	0
Change in fair value of contingent consideration included in earnings	(325)
Payment of contingent consideration	3,000	[1]
Foreign currency translation adjustment	166
Balance as of March 28, 2015	$ (3,361)

[1] Contingent consideration payment relates to an acquisition completed prior to 2015.