CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 02, 2020	Sep. 27, 2019	Oct. 02, 2020	Sep. 27, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 3,892	$ 2,388	$ 2,586	$ 7,669
Defined benefit plans:
Net change in plan assets	(334)	(1,037)	(387)	(1,677)
Reclassification into other income, net	70	26	212	80
Foreign currency translation loss	316	(22)	402	317
Tax effect	(68)	115	(104)	80
Other comprehensive income (loss), net of tax	(16)	(918)	123	(1,200)
Comprehensive income	$ 3,876	$ 1,470	$ 2,709	$ 6,469