CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 27, 2019		Sep. 28, 2018		Sep. 27, 2019		Sep. 28, 2018
Statement Of Income And Comprehensive Income [Abstract]
Consolidated net income		$ 8,923	[1]	$ 14,989	[2]	$ 31,556	[1]	$ 39,451	[2]
Other comprehensive income (loss):
Foreign currency translation adjustments, net of tax	[3]	(2,821)		(490)		(3,144)		(2,482)
Pension liability adjustments, net of tax	[4]	490		223		1,060		978
Total other comprehensive income		(2,331)		(267)		(2,084)		(1,504)
Total consolidated comprehensive income		6,592		14,722		29,472		37,947
Less: Comprehensive income attributable to noncontrolling interest				(435)				(1,986)
Comprehensive income attributable to Novanta Inc.		$ 6,592		$ 14,287		$ 29,472		$ 35,961

[1] 47,147 performance-based restricted stock units granted to certain members of the executive management team and 213,219 shares of restricted stock issued to Laser Quantum former non-controlling interest holders are considered contingently issuable shares and were excluded from the calculation of the denominator as the contingent conditions had not been met as of September 27, 2019.

[2] 53,968 performance-based restricted stock units granted to certain members of the executive management team and 213,219 shares of restricted stock issued to Laser Quantum former non-controlling interest holders were considered contingently issuable shares and were excluded from the calculation of the denominator as the contingent conditions had not been met as of September 28, 2018.

[3] The tax effect on this component of comprehensive income was nominal for all periods presented.

[4] The tax effect on this component of comprehensive income was nominal for all periods presented. See Note 4 for the total amount of pension liability adjustments reclassified out of accumulated other comprehensive income (loss).