Earnings per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 29, 2012	Sep. 29, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Oct. 01, 2011		Jul. 02, 2011	Apr. 02, 2011	Dec. 29, 2012	Dec. 31, 2011	Jan. 01, 2011
Amounts Attributable to Kadant [Abstract]
Income from Continuing Operations	$ 9,603	$ 7,617	$ 6,546	$ 7,114	$ 10,676	$ 9,804	[1]	$ 7,309	$ 5,795	$ 30,880	$ 33,584	$ 18,409
Income (Loss) from Discontinued Operation										743	(9)	98
Net Income	$ 9,566	$ 8,461	$ 6,543	$ 7,053	$ 11,832	$ 8,648		$ 7,304	$ 5,791	$ 31,623	$ 33,575	$ 18,507
Basic Weighted Average Shares (in shares)										11,456,000	12,124,000	12,339,000
Effect of Stock Options, Restricted Stock Units and Employee Stock Purchase Plan (in shares)										134,000	137,000	127,000
Diluted Weighted Average Shares (in shares)										11,590,000	12,261,000	12,466,000
Basic Earnings Per Share [Abstract]
Continuing operations (in dollars per share)	$ 0.85	$ 0.67	$ 0.57	$ 0.61	$ 0.91	$ 0.81		$ 0.59	$ 0.47	$ 2.70	$ 2.77	$ 1.49
Discontinued operation (in dollars per share)										$ 0.06	$ 0	$ 0.01
Net Income per Basic Share (in dollars per share)	$ 0.85	$ 0.75	$ 0.57	$ 0.61	$ 1.01	$ 0.71		$ 0.59	$ 0.47	$ 2.76	$ 2.77	$ 1.50
Diluted Earnings Per Share [Abstract]
Continuing operations (in dollars per share)	$ 0.84	$ 0.66	$ 0.56	$ 0.61	$ 0.90	$ 0.80		$ 0.59	$ 0.47	$ 2.66	$ 2.74	$ 1.48
Discontinued operation (in dollars per share)										$ 0.06	$ 0	$ 0
Net Income per Diluted Share (in dollars per share)	$ 0.83	$ 0.74	$ 0.56	$ 0.60	$ 1.00	$ 0.70		$ 0.59	$ 0.47	$ 2.73	$ 2.74	$ 1.48
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)										150,000	67,500	99,300
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)										28,500	45,700

[1] Includes a $2.3 million pre-tax gain on the sale of real estate in the third quarter of 2011.