Acquisition of Senhance Surgical Robotic System - Summary of Business Acquisition, Pro Forma Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Net loss per share	$ 0.57	$ 0.63
Senhance Surgical Robotic System Acquisition [Member]
Business Acquisition [Line Items]
Revenue	$ 77	$ 401
Net loss	$ 53,994	$ 46,874