Inventories - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Inventory [Line Items]
Inventory write-down related to restructuring	$ 7,400,000
Write down of inventory	1,523,000	$ 0
SurgiBot System
Inventory [Line Items]
Write down of inventory	$ 1,500,000	$ 0