Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 25, 2021	Jun. 26, 2020	Jun. 25, 2021	Jun. 26, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (1,056)	$ (3,229)	$ (7,092)	$ (22,247)
Other comprehensive loss, net of tax:
Foreign currency translation adjustments	32	117	(20)	(317)
Comprehensive loss	(1,024)	(3,112)	(7,112)	(22,564)
Comprehensive loss attributable to noncontrolling interest	(12)	(16)	(34)	(40)
Comprehensive loss attributable to Company	$ (1,012)	$ (3,096)	$ (7,078)	$ (22,524)