Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 25, 2020	Sep. 27, 2019	Sep. 25, 2020	Sep. 27, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net Income	$ 2,831	$ 879	$ 5,734	$ 2,454
Foreign currency translation adjustment, net of taxes	2,117	(1,540)	2,061	(2,019)
Change in pension, net of taxes of $2 and $0 in the 2020 and 2019 third quarters, respectively, and $1 and $0 in the first three quarters of 2020 and 2019, respectively	(135)	258	(74)	356
Other comprehensive income (loss)	1,982	(1,282)	1,987	(1,663)
Comprehensive income (loss)	$ 4,813	$ (403)	$ 7,721	$ 791