Acquisition of ALF-X Surgical Robotic System - Schedule of Estimated Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 21, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill	$ 116,054		$ 93,842
ALF-X Surgical Robotic System Acquisition [Member]
Business Acquisition [Line Items]
Accounts receivable		$ 78
Inventories		3,200
Current deferred tax asset		351
Other current assets		4,180
Property and equipment		1,384
Intellectual property		62,500
In-process research and development		22,300
Goodwill		22,315
Total assets acquired		116,308
Accounts payable and other liabilities		1,915
Long-term deferred tax liabilities		21,416
Net assets acquired		$ 92,977