Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Dec. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term marketable securities	$ 12,078		$ 4,982
Total
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term marketable securities	12,078		4,982
Foreign currency forward exchange contracts, net	(99)		77
Total fair value of financial instruments	11,979		5,059
Level 1
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term marketable securities	12,078		4,982
Foreign currency forward exchange contracts, net	0		0
Total fair value of financial instruments	12,078		4,982
Unrealized loss (less than)	100	$ 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	(99)		77
Total fair value of financial instruments	(99)		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