Earnings per Share - Computation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 30, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Earnings Per Share [Abstract]
Income from Continuing Operations					$ 7,733	$ 9,154	$ 8,311	$ 6,876	$ 31,092	$ 32,074	$ 34,315
Income from Discontinued Operation					0	3	0	0	0	3	74
Net Income Attributable to Kadant	$ 760	$ 13,285	$ 8,096	$ 8,951	$ 7,733	$ 9,157	$ 8,311	$ 6,876	$ 31,092	$ 32,077	$ 34,389
Basic Weighted Average Shares									10,991	10,869	10,867
Effect of Stock Options, Restricted Stock Units and Employee Stock Purchase Plan									321	280	227
Diluted Weighted Average Shares									11,312	11,149	11,094
Basic EPS:
Continuing Operations (in dollars per share)					$ 0.71	$ 0.84	$ 0.76	$ 0.64	$ 2.83	$ 2.95	$ 3.16
Discontinued Operation (in dollars per share)									0.00	0.00	0.01
Net Income per Basic Share (in dollars per share)	$ 0.07	$ 1.21	$ 0.74	$ 0.82	0.71	0.84	0.76	0.64	2.83	2.95	3.16
Diluted EPS:
Continuing Operations (in dollars per share)					0.69	0.82	0.75	0.62	2.75	2.88	3.09
Discontinued Operation (in dollars per share)									0.00	0.00	0.01
Net Income per Diluted Share (in dollars per share)	$ 0.07	$ 1.17	$ 0.72	$ 0.80	$ 0.69	$ 0.82	$ 0.75	$ 0.62	$ 2.75	$ 2.88	$ 3.10