Business Combination - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Oct. 16, 2017	Dec. 31, 2017	Dec. 31, 2016	Sep. 30, 2017
Business Acquisition [Line Items]
Acquisition, net of cash acquired		$ 2,991	$ 0
Common stock, par value (in dollars per share)		$ 0.001		$ 0.001
Acquisition-related contingent consideration		$ 3,120		$ 354
ICAR Vision Systems, S.L.
Business Acquisition [Line Items]
Acquisition, net of cash acquired	$ 3,000
Shares issued as consideration for acquisition	584,291
Common stock issued during acquisition, value	$ 5,600
Common stock, par value (in dollars per share)	$ 0.001
Acquisition-related contingent consideration		2,900
Contingent consideration recognized in acquisition-related costs and expenses		$ 300
Cash payment into an escrow fund to serve as collateral and partial security for working capital adjustments and certain indemnification rights	$ 1,500
Business acquisitions expenses	400
ICAR Vision Systems, S.L. | Q4 Consideration
Business Acquisition [Line Items]
Contingent consideration	1,500
ICAR Vision Systems, S.L. | Earnout Consideration
Business Acquisition [Line Items]
Contingent consideration	$ 3,800