Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term marketable securities	$ 12,086	$ 4,982
Total
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term marketable securities	12,086	4,982
Foreign currency forward exchange contracts, net	36	77
Total fair value of financial instruments	12,122	5,059
Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term marketable securities	12,086	4,982
Foreign currency forward exchange contracts, net	0	0
Total fair value of financial instruments	12,086	4,982
Unrealized gain (loss)	100
Level 2
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term marketable securities	0	0
Foreign currency forward exchange contracts, net	36	77
Total fair value of financial instruments	36	77
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term marketable securities	0	0
Foreign currency forward exchange contracts, net	0	0
Total fair value of financial instruments	$ 0	$ 0