Condensed Consolidated Statement of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenues	$ 165,745	$ 152,794	$ 469,851	$ 365,893
Costs and Operating Expenses:
Cost of revenues	92,652	88,139	262,515	199,369
Selling, general, and administrative expenses	42,888	42,346	133,796	115,936
Research and development expenses	2,452	2,635	8,049	7,004
Restructuring costs	378	0	1,717	0
Total Costs and Operating Expenses	138,370	133,120	406,077	322,309
Operating Income	27,375	19,674	63,774	43,584
Interest Income	30	94	335	300
Interest Expense	(1,738)	(1,282)	(5,320)	(2,022)
Other Expense, Net (Note 7)	(245)	(216)	(736)	(637)
Income Before Provision for Income Taxes	25,422	18,270	58,053	41,225
Provision for Income Taxes (Note 4)	6,443	4,860	15,575	10,550
Net Income	18,979	13,410	42,478	30,675
Net Income Attributable to Noncontrolling Interest	(195)	(125)	(487)	(343)
Net Income Attributable to Kadant	$ 18,784	$ 13,285	$ 41,991	$ 30,332
Earnings per Share Attributable to Kadant (Note 3):
Basic (in dollars per share)	$ 1.69	$ 1.21	$ 3.79	$ 2.76
Diluted (in dollars per share)	$ 1.64	$ 1.17	$ 3.69	$ 2.69
Weighted Average Shares (Note 3):
Basic (in shares)	11,101	11,004	11,078	10,986
Diluted (in shares)	11,421	11,344	11,388	11,282
Cash Dividends Declared per Common Share (in dollars per share)	$ 0.22	$ 0.21	$ 0.66	$ 0.63