Condensed Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 02, 2021	Sep. 26, 2020	Oct. 02, 2021	Sep. 26, 2020
Statement of Comprehensive Income [Abstract]
Net Income	$ 20,698	$ 14,980	$ 60,521	$ 39,358
Other Comprehensive Items:
Foreign currency translation adjustment	(7,326)	8,656	(7,987)	824
Post-retirement liability adjustments, net (net of tax provision (benefit) of $9, $(6), $21 and $14)	24	(14)	57	34
Effect of post-retirement plan settlement	0	0	0	(119)
Deferred gain (loss) on cash flow hedges (net of tax provision (benefit) of $20, $19, $60 and $(103))	66	51	244	(275)
Other comprehensive items	(7,236)	8,693	(7,686)	464
Comprehensive Income	13,462	23,673	52,835	39,822
Comprehensive Income Attributable to Noncontrolling Interest	(201)	(191)	(546)	(445)
Comprehensive Income Attributable to Kadant	$ 13,261	$ 23,482	$ 52,289	$ 39,377