Acquisitions - Schedule of Estimated Fair Values of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Oct. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 21, 2015
Business Acquisition [Line Items]
Goodwill	$ 80,131		$ 71,368	$ 68,697	$ 130,869
Medical Surgery Technologies Ltd. [Member]
Business Acquisition [Line Items]
Property and equipment		$ 43
In-process research and development		10,633
Goodwill	9,600	9,638
Net assets acquired		$ 20,314
Senhance Surgical Robotic System Acquisition [Member]
Business Acquisition [Line Items]
Accounts receivable						$ 78
Inventories						2,800
Current deferred tax asset						526
Other current assets						4,180
Property and equipment						1,384
Intellectual property						48,500
In-process research and development						17,100
Goodwill	$ 38,300					38,348
Total assets acquired						112,916
Accounts payable and other liabilities						1,915
Long-term deferred tax liabilities						18,424
Net assets acquired						$ 92,577