Goodwill, In-Process Research and Development and Intellectual Property - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended		12 Months Ended
	Sep. 21, 2015	Nov. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2009
Goodwill And Intangible Assets [Line Items]
Goodwill					$ 71,368,000	$ 68,697,000	$ 130,869,000
Accumulated impairment of goodwill					61,800,000	61,800,000
Goodwill impairment			$ 0	$ 61,784,000	0	61,784,000	0
In-Process Research and Development [Member]
Goodwill And Intangible Assets [Line Items]
Discount rate	45.00%
Patents [Member]
Goodwill And Intangible Assets [Line Items]
Patent purchased amount						5,000,000		$ 5,000,000
Write-off of intellectual property						1,562,000
Patents [Member] | SurgiBot System [Member]
Goodwill And Intangible Assets [Line Items]
Write-off of intellectual property					0	1,600,000	$ 0
Intellectual Property [Member]
Goodwill And Intangible Assets [Line Items]
Discount rate	45.00%
Patent purchased amount					66,813,000	53,500,000
Write-off of intellectual property						1,562,000
Technology and Patents Purchased [Member]
Goodwill And Intangible Assets [Line Items]
Patent purchased amount					$ 400,000
Weighted average remaining useful life					9 years 3 months 18 days
Developed Technology [Member]
Goodwill And Intangible Assets [Line Items]
Patent purchased amount					$ 66,413,000	$ 48,500,000
Weighted average remaining useful life					4 years 9 months 18 days
Safe Stitch Medical Inc [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill					$ 93,800,000
Senhance Surgical Robotic System Acquisition [Member]
Goodwill And Intangible Assets [Line Items]
Goodwill	$ 38,348,000				38,300,000
Intellectual property	48,500,000
Acquisition price	92,577,000	$ 400,000
Senhance Surgical Robotic System Acquisition [Member] | In-Process Research and Development [Member]
Goodwill And Intangible Assets [Line Items]
In-process research and development	$ 17,100,000
Senhance Surgical Robotic System Acquisition [Member] | Technology and Patents Purchased [Member]
Goodwill And Intangible Assets [Line Items]
Acquisition price					$ 400,000