Condensed Consolidated Statement of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 28, 2019	Sep. 29, 2018
Income Statement [Abstract]
Revenues (Notes 1 and 12)	$ 173,504	$ 165,745	$ 521,985	$ 469,851
Costs and Operating Expenses:
Cost of revenues	99,257	92,652	302,852	262,515
Selling, general, and administrative expenses	47,097	42,888	144,883	133,796
Research and development expenses	2,597	2,452	7,980	8,049
Restructuring costs (Note 13)	0	378	0	1,717
Total Costs and Operating Expenses	148,951	138,370	455,715	406,077
Operating Income	24,553	27,375	66,270	63,774
Interest Income	43	30	158	335
Interest Expense	(3,066)	(1,738)	(10,143)	(5,320)
Other Expense, Net (Note 7)	(98)	(245)	(296)	(736)
Income Before Provision for Income Taxes	21,432	25,422	55,989	58,053
Provision for Income Taxes (Note 4)	5,219	6,443	12,310	15,575
Net Income	16,213	18,979	43,679	42,478
Net Income Attributable to Noncontrolling Interest	(98)	(195)	(360)	(487)
Net Income Attributable to Kadant	$ 16,115	$ 18,784	$ 43,319	$ 41,991
Earnings per Share Attributable to Kadant (Note 3):
Basic (in dollars per share)	$ 1.43	$ 1.69	$ 3.87	$ 3.79
Diluted (in dollars per share)	$ 1.41	$ 1.64	$ 3.79	$ 3.69
Weighted Average Shares (Note 3):
Basic (in shares)	11,267	11,101	11,198	11,078
Diluted (in shares)	11,469	11,421	11,434	11,388