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Restructuring Costs - Summary of Changes in Accrued Restructuring Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Restructuring Cost and Reserve [Line Items]
Beginning balance			$ 203
(Reversal) provision	$ 569	$ 0	1,339	$ 0
Usage			(1,371)
Currency translation			(14)
Ending balance	157		157
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Beginning balance			203
(Reversal) provision			(55)
Usage			0
Currency translation			(11)
Ending balance	137		137
Employee Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Beginning balance			0
(Reversal) provision			1,018
Usage			(1,015)
Currency translation			(3)
Ending balance	0		0
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Beginning balance			0
(Reversal) provision			376
Usage			(356)
Currency translation			0
Ending balance	$ 20		$ 20