Computation of Basic and Diluted Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 27, 2019		Sep. 28, 2018		Sep. 27, 2019		Sep. 28, 2018
Numerators:
Consolidated net income		$ 8,923	[1]	$ 14,989	[2]	$ 31,556	[1]	$ 39,451	[2]
Less: Net income attributable to noncontrolling interest	[2]			(435)				(1,986)
Net income attributable to Novanta Inc.		8,923	[1]	14,554	[2]	31,556	[1]	37,465	[2]
Redeemable noncontrolling interest redemption value adjustment	[2]			6,877				1,781
Net income attributable to Novanta Inc. after adjustment for redeemable noncontrolling interest redemption value		$ 8,923	[1]	$ 21,431	[2]	$ 31,556	[1]	$ 39,246	[2]
Denominators:
Weighted average common shares outstanding—basic		35,074	[1]	34,899	[2]	35,012	[1]	34,918	[2]
Dilutive potential common shares		511	[1]	586	[2]	511	[1]	551	[2]
Weighted average common shares outstanding— diluted		35,585	[1]	35,485	[2]	35,523	[1]	35,469	[2]
Antidilutive potential common shares excluded from above	[1]	35				43
Earnings per Common Share Attributable to Novanta Inc.:
Basic		$ 0.25	[1]	$ 0.61	[2]	$ 0.90	[1]	$ 1.12	[2]
Diluted		$ 0.25	[1]	$ 0.60	[2]	$ 0.89	[1]	$ 1.11	[2]

[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.