Condensed Consolidated Statement of Comprehensive (Loss) Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Statement of Comprehensive Income [Abstract]
Net Income	$ 12,491	$ 8,198	$ 23,499	$ 17,265
Other Comprehensive Items:
Foreign currency translation adjustment	(15,776)	8,655	(10,440)	13,687
Pension and other post-retirement liability adjustments (net of tax provision of $75, $11, $109 and $60)	212	81	329	163
Deferred (loss) gain on cash flow hedges (net of tax (benefit) provision of ($55), $1, ($47) and $16)	(173)	7	(80)	34
Other Comprehensive Items	(15,737)	8,743	(10,191)	13,884
Comprehensive (Loss) Income	(3,246)	16,941	13,308	31,149
Comprehensive Income Attributable to Noncontrolling Interest	(46)	(219)	(239)	(381)
Comprehensive (Loss) Income Attributable to Kadant	$ (3,292)	$ 16,722	$ 13,069	$ 30,768