Note 11 - Commitments and Contingencies (Details Textual) $ in Thousands, € in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2021 EUR (€)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Business Combination, Contingent Consideration, Liability, Total	$ 4,949		$ 4,949			$ 3,936
Operating Lease, Weighted Average Discount Rate, Percent	7.80%		7.80%			8.20%
Operating Lease, Right-of-Use Asset	$ 4,328		$ 4,328			$ 1,164
Operating Lease, Liability, Total	4,559		4,559
Operating Lease, Liability, Current	671		671			686
Operating Lease, Liability, Noncurrent	3,888		3,888			$ 628
Operating Lease, Cost	$ 400	$ 500	$ 1,300		$ 1,500
Operating Lease, Weighted Average Remaining Lease Term (Year)	8 years 6 months		8 years 6 months
Operating Lease, Payments	$ 300	$ 400	$ 800		$ 1,100
Minimum [Member]
Lessee, Operating Lease, Discount Rate	6.10%		6.10%
Maximum [Member]
Lessee, Operating Lease, Discount Rate	8.50%		8.50%
Senhance Surgical Robotic System Acquisition[Member]
Business Combination, Contingent Consideration, Liability, Total	$ 4,900		$ 4,900
Senhance Surgical Robotic System Acquisition[Member] | License and Supply Agreement [Member]
Contractual Obligation, to be Paid, Remainder of Fiscal Year	3,200		3,200
Contractual Obligation, to be Paid, Year One	100		100
Contractual Obligation, to be Paid, Year Two	300		300
Contractual Obligation, to be Paid, Year Three	200		200
Contractual Obligation, to be Paid, after Year Three	$ 200		$ 200
Senhance Surgical Robotic System Acquisition[Member] | Minimum [Member]
Business Combination Contingent Consideration Arrangements Target Revenue | €				€ 25