Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (2,780)	$ (2,419)	$ (4,431)	$ (5,467)
Foreign currency translation adjustments	(9)	(12)	(7)	(4)
Comprehensive loss	$ (2,789)	$ (2,431)	$ (4,438)	$ (5,471)