CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Income And Comprehensive Income [Abstract]
Consolidated net income		$ 62,307	$ 22,003	$ 35,615
Other comprehensive income (loss):
Foreign currency translation adjustments, net of tax	[1]	8,909	(7,524)	(4,083)
Pension liability adjustments, net of tax	[2]	926	(1,361)	1,709
Total other comprehensive income (loss)		9,835	(8,885)	(2,374)
Total consolidated comprehensive income		72,142	13,118	33,241
Less: Comprehensive income attributable to noncontrolling interest		(2,256)
Comprehensive income attributable to Novanta Inc.		$ 69,886	$ 13,118	$ 33,241

[1] The tax effect on this component of comprehensive income was ($94), $36 and $193 in 2017, 2016 and 2015, respectively.

[2] The tax effect on this component of comprehensive income was $277, ($462) and $307 in 2017, 2016 and 2015, respectively.