Inventories - Components of Inventories (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 30, 2017
Inventory Disclosure [Abstract]
Raw materials	$ 3,659	$ 4,147
Work in process	1,021	1,567
Finished goods	4,626	3,667
Total inventories	$ 9,306	$ 9,381	[1]

[1] Derived from the audited consolidated financial statements included in the Annual Report on Form 10-K filed with the SEC for the year ended December 30, 2017.