Computation of Basic and Diluted Earnings (Loss) per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017		Sep. 30, 2016
Numerators:
Income from continuing operations		$ 8,366	$ 7,470	$ 52,630		$ 14,247
Less: Net income attributable to noncontrolling interest		(834)		(1,444)
Net income attributable to Novanta Inc.		7,532	7,470	51,186		14,247
Less: Adjustment of redeemable noncontrolling interest to estimated redemption value (see Note 14)		(7,585)		(11,303)	[1]
Net income (loss) attributable to Novanta Inc. after adjustment of redeemable noncontrolling interest to estimated redemption value		$ (53)	$ 7,470	$ 39,883		$ 14,247
Denominators:
Weighted average common shares outstanding—basic		34,833	34,677	34,809		34,689
Dilutive potential common shares	[2]		251	426		200
Weighted average common shares outstanding— diluted		34,833	34,928	35,235		34,889
Antidilutive common shares excluded from above			144			112
Basic Earnings (Loss) per Common Share:
Basic earnings (loss) per common share attributable to Novanta Inc.		$ 0.00	$ 0.22	$ 1.15		$ 0.41
Diluted Earnings (Loss) per Common Share:
Diluted earnings (loss) per common share attributable to Novanta Inc.		$ 0.00	$ 0.21	$ 1.13		$ 0.41

[1] Adjustment of the carrying value of redeemable noncontrolling interest to the estimated redemption value was recognized in retained earnings instead of the consolidated statement of operations but was included in the computation of earnings per share attributable to Novanta Inc. (see Note 5.)

[2] Due to the Company’s net loss position after adjustment of redeemable noncontrolling interest to estimated redemption value for the three months ended September 29, 2017, all potentially dilutive shares are excluded from the calculation of the denominator as their effect would have been anti-dilutive.