Computation of Basic and Diluted Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Mar. 29, 2019	[1]	Mar. 30, 2018
Numerators:
Consolidated net income		$ 12,253		$ 12,837	[2]
Less: Net income attributable to noncontrolling interest	[2]			(926)
Net income attributable to Novanta Inc.		12,253		11,911	[2]
Redeemable noncontrolling interest redemption value adjustment	[2]			(5,399)
Net income attributable to Novanta Inc. after adjustment for redeemable noncontrolling interest redemption value		$ 12,253		$ 6,512	[2]
Denominators:
Weighted average common shares outstanding—basic		34,958		34,887	[2]
Dilutive potential common shares		516		541	[2]
Weighted average common shares outstanding— diluted		35,474		35,428	[2]
Antidilutive common shares excluded from above		58		12	[2]
Earnings per Common Share Attributable to Novanta Inc.:
Basic		$ 0.35		$ 0.19	[2]
Diluted		$ 0.35		$ 0.18	[2]

[1] 45,252 non-GAAP EPS performance 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 are excluded from the calculation of the denominator as the contingent conditions had not been met as of March 29, 2019.

[2] 53,968 non-GAAP EPS performance restricted stock units granted to certain members of the executive management team were considered contingently issuable shares and were excluded from the calculation of the denominator as the contingent conditions had not been met as of March 30, 2018.