Earnings per Share - Computation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Jan. 01, 2022	Jan. 02, 2021	Dec. 28, 2019
Earnings Per Share [Abstract]
Net Income Attributable to Kadant	$ 84,043	$ 55,196	$ 52,068
Basic Weighted Average Shares	11,579	11,482	11,235
Effect of Stock Options, Restricted Stock Units and Employee Stock Purchase Plan Shares	76	82	222
Diluted Weighted Average Shares	11,655	11,564	11,457
Basic (in dollars per share)	$ 7.26	$ 4.81	$ 4.63
Diluted (in dollars per share)	$ 7.21	$ 4.77	$ 4.54