Acquisition of Senhance Surgical Robotic System - Additional Information (Detail) - Senhance Surgical Robotic System Acquisition [Member]			9 Months Ended
	Dec. 30, 2016 EUR (€) shares	Sep. 21, 2015 USD ($) shares	Sep. 30, 2018 EUR (€)	Dec. 31, 2016 USD ($)	Sep. 21, 2015 EUR (€)
Business Acquisition [Line Items]
Common shares issued | shares		15,543,413
First Tranche [Member]
Business Acquisition [Line Items]
Cash consideration | $		$ 25,000,000
Second Tranche [Member]
Business Acquisition [Line Items]
Common shares issued | shares	3,722,685
Aggregate fair market value	€ 5,000,000
Aggregate fair market value payment	€ 5,000,000
Second Tranche [Member] | Lincoln Park Capital Fund, LLC [Member]
Business Acquisition [Line Items]
Gross proceeds from financing | $				$ 50,000,000
Interest rate				9.00%
Second Tranche [Member] | Minimum [Member] | Lincoln Park Capital Fund, LLC [Member]
Business Acquisition [Line Items]
Cash on hand | $				$ 50,000,000
Third Tranche [Member]
Business Acquisition [Line Items]
Cash consideration payable					€ 15,000,000
Third Tranche [Member] | Minimum [Member]
Business Acquisition [Line Items]
Target revenue to be achieved					25,000,000
Fourth Tranche [Member]
Business Acquisition [Line Items]
Cash consideration			€ 2,100,000
Cash consideration payable					2,500,000
U.S. Dollars [Member]
Business Acquisition [Line Items]
Cash consideration | $		$ 25,000,000
Euro [Member]
Business Acquisition [Line Items]
Cash consideration payable					€ 27,500,000