Financial Instruments Measured at Fair Value - Unobservable Inputs Reconciliation (Details) - Fair Value, Inputs, Level 3 [Member] - Fair Value, Measurements, Recurring [Member] - Contingent Consideration [Member] $ in Thousands		6 Months Ended
		Jun. 27, 2015 USD ($)
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		(448)
Payment of contingent consideration	[1]	3,000
Foreign currency translation adjustment		122
Balance as of June 27, 2015		$ (3,528)

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