Summary of Unaudited Pro Forma Financial Information (Parenthetical) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016
Business Combinations [Abstract]
Adjustment of redeemable noncontrolling interest to estimated redemption value	$ 20,244	[1]	$ 0

[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 9).