Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Dec. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term marketable securities	$ 9,600		$ 4,982
Unrealized gain (loss) on marketable securities	100	$ (100)
Total
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term marketable securities	9,600		4,982
Foreign currency forward exchange contracts, net	105		77
Total fair value of financial instruments	9,705		5,059
Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term marketable securities	9,600		4,982
Foreign currency forward exchange contracts, net	0		0
Total fair value of financial instruments	9,600		4,982
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	105		77
Total fair value of financial instruments	105		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