Earnings per Share - Computation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Oct. 01, 2016	Jul. 02, 2016	Apr. 02, 2016	Jan. 02, 2016	Oct. 03, 2015	Jul. 04, 2015	Apr. 04, 2015	Dec. 31, 2016	Jan. 02, 2016	Jan. 03, 2015
Earnings Per Share [Abstract]
Income from Continuing Operations	$ 7,733	$ 9,154	$ 8,311	$ 6,876	$ 10,367	$ 8,647	$ 8,469	$ 6,832	$ 32,074	$ 34,315	$ 28,682
Income (Loss) from Discontinued Operation	0	3	0	0	18	(4)	(5)	65	3	74	(23)
Net Income Attributable to Kadant	$ 7,733	$ 9,157	$ 8,311	$ 6,876	$ 10,385	$ 8,643	$ 8,464	$ 6,897	$ 32,077	$ 34,389	$ 28,659
Basic Weighted Average Shares									10,869	10,867	10,988
Effect of Stock Options, Restricted Stock Units and Employee Stock Purchase Plan									280	227	222
Diluted Weighted Average Shares									11,149	11,094	11,210
Basic EPS:
Continuing Operations (in dollars per share)	$ 0.71	$ 0.84	$ 0.76	$ 0.64	$ 0.96	$ 0.80	$ 0.77	$ 0.63	$ 2.95	$ 3.16	$ 2.61
Discontinued Operation (in dollars per share)									0.00	0.01	0.00
Net Income per Basic Share (in dollars per share)	0.71	0.84	0.76	0.64	0.96	0.80	0.77	0.63	2.95	3.16	2.61
Diluted EPS:
Continuing Operations (in dollars per share)	0.69	0.82	0.75	0.62	0.94	0.78	0.76	0.62	2.88	3.09	2.56
Discontinued Operation (in dollars per share)									0.00	0.01	0.00
Net Income per Diluted Share (in dollars per share)	$ 0.69	$ 0.82	$ 0.75	$ 0.62	$ 0.94	$ 0.78	$ 0.76	$ 0.62	$ 2.88	$ 3.10	$ 2.56