Goodwill, In-Process Research and Development and Intellectual Property - Additional Information (Detail) - USD ($)			3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 31, 2018	Sep. 21, 2015	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Goodwill And Intangible Assets [Line Items]
Goodwill			$ 0		$ 0		$ 80,131,000
Goodwill and intangible assets impairment					86,881,000	$ 0	0
Goodwill impairment			78,969,000	$ 0	78,969,000	0	0
Accumulated impairment of goodwill			140,800,000		140,800,000		$ 61,800,000
Impairment of intangible assets			7,912,000	$ 0	7,912,000	$ 0
In-Process Research and Development
Goodwill And Intangible Assets [Line Items]
Discount rate	15.00%	45.00%
Impairment of intangible assets					$ 7,912,000
Intellectual Property
Goodwill And Intangible Assets [Line Items]
Discount rate		45.00%
Technology and Patents Purchased
Goodwill And Intangible Assets [Line Items]
Weighted average remaining useful life					7 years 7 months 6 days		8 years 3 months 18 days
Developed Technology
Goodwill And Intangible Assets [Line Items]
Weighted average remaining useful life					3 years		3 years 9 months 18 days
Safe Stitch Medical Inc
Goodwill And Intangible Assets [Line Items]
Goodwill			93,800,000		$ 93,800,000
Senhance Surgical Robotic System Acquisition
Goodwill And Intangible Assets [Line Items]
Goodwill			38,300,000		38,300,000
Intellectual property		$ 48,500,000
Senhance Surgical Robotic System Acquisition | In-Process Research and Development
Goodwill And Intangible Assets [Line Items]
In-process research and development		$ 17,100,000
Medical Surgery Technologies Ltd.
Goodwill And Intangible Assets [Line Items]
Goodwill	$ 9,638,000		$ 9,600,000		$ 9,600,000
Medical Surgery Technologies Ltd. | In-Process Research and Development
Goodwill And Intangible Assets [Line Items]
In-process research and development	$ 10,600,000