Redeemable Noncontrolling Interest- Additional Information (Details) $ in Thousands, £ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	[1]	Dec. 31, 2016 USD ($)	Jan. 10, 2017 USD ($)	Jan. 10, 2017 GBP (£)
Minority Interest [Line Items]
Adjustment of redeemable noncontrolling interest to estimated redemption value	$ 20,244		$ 0
Laser Quantum
Minority Interest [Line Items]
Percentage of equity interest held before acquisition			41.00%	41.00%	41.00%
Percentage of equity interest held after acquisition				76.00%	76.00%
Initial fair value of noncontrolling interest				$ 21,582	£ 17.7

[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).