Note 2 - Summary of Significant Accounting Policies 1 (Details Textual)						3 Months Ended				6 Months Ended		12 Months Ended
	Jul. 06, 2020 USD ($)	Jun. 08, 2020 USD ($) shares	Apr. 27, 2020 USD ($)	Mar. 10, 2020 USD ($)	Dec. 11, 2019 shares	Jun. 30, 2020 USD ($) shares	Dec. 31, 2019 USD ($) shares	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) shares	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) shares	Dec. 10, 2019 shares
Common Stock, Shares, Outstanding, Ending Balance (in shares) | shares					20,200,000	56,902,140	20,691,301			56,902,140		20,691,301	261,900,000
Retained Earnings (Accumulated Deficit), Ending Balance						$ (694,038,000)	$ (663,600,000)			$ (694,038,000)		$ (663,600,000)
Working Capital						24,300,000				24,300,000
Proceeds from Issuance of Equity Net										13,525,000	$ 0
Cash and Cash Equivalents, at Carrying Value, Ending Balance						15,603,000	9,598,000			15,603,000		9,598,000
Restricted Cash and Cash Equivalents, Noncurrent, Total						600,000	1,000,000.0			600,000		1,000,000.0
Accounts Receivable, Allowance for Credit Loss, Ending Balance						1,700,000	1,700,000			1,700,000		1,700,000
Impairment of Intangible Assets, Finite-lived										$ 0	0
Goodwill, Impairment Loss							79,000,000.0
Period Of Service Sale Arrangement (Year)										5 years
Period of Service Sale Arrangement at Stated Service Price (Year)										4 years
Operating Lease, Lease Income, Total						100,000			$ 0	$ 200,000	0
Revenue, Remaining Performance Obligation, Amount						3,000,000.0	3,700,000			3,000,000.0		3,700,000
Contract with Customer, Asset, after Allowance for Credit Loss, Current, Total						100,000	200,000			100,000		200,000
Contract with Customer, Liability, Revenue Recognized						400,000			400,000	600,000	700,000
Inventory Write-down						0			800,000	0	761,000
Share-based Payment Arrangement, Expense						1,900,000			3,400,000	$ 3,900,000	6,300,000
Share-based Compensation Arrangement by Share-based Payment Award, Options and RSUs, Grants in Period, Grant Date Value Per Non-employee Director		$ 45,000
Common Stock, Capital Shares Reserved for Future Issuance (in shares) | shares		2,061,289
Number of Operating Segments										1
Assets, Total						75,974,000	74,779,000			$ 75,974,000		74,779,000
Non-US [Member]
Assets, Total						56,400,000	60,500,000			56,400,000		$ 60,500,000
System Sold in 2017 [Member]
Contract with Customer, Liability, Revenue Recognized									1,300,000		1,300,000
Safe Stitch Medical Inc [Member]
Goodwill, Ending Balance						93,800,000				93,800,000
Senhance Surgical Robotic System Acquisition [Member]
Goodwill, Ending Balance						38,300,000				38,300,000
Medical Surgery Technologies Limited [Member]
Goodwill, Ending Balance						9,600,000				$ 9,600,000
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options and RSUs, Grants in Period, Grant Date Value		$ 5,000
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options and RSUs, Grants in Period, Grant Date Value		$ 10,000
Patents [Member]
Finite-Lived Intangible Asset, Useful Life (Year)										10 years
Developed Technology Rights [Member] | Minimum [Member]
Finite-Lived Intangible Asset, Useful Life (Year)										5 years
Developed Technology Rights [Member] | Maximum [Member]
Finite-Lived Intangible Asset, Useful Life (Year)										7 years
In Process Research and Development [Member]
Impairment of Intangible Assets, Finite-lived						$ 0	$ 0	$ 7,900,000	$ 0	$ 0	$ 0
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Eight Customers [Member]
Number of Major Customers										8		8
Concentration Risk, Percentage										76.00%		85.00%
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Seven Customers [Member]
Number of Major Customers						7
Concentration Risk, Percentage						60.00%
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Five Customers [Member]
Number of Major Customers									5
Concentration Risk, Percentage									91.00%
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Nine Customers [Member]
Number of Major Customers										9
Concentration Risk, Percentage										65.00%
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Two Customers [Member]
Number of Major Customers											2
Concentration Risk, Percentage											76.00%
Revenue Benchmark [Member] | Geographic Concentration Risk [Member] | UNITED STATES
Concentration Risk, Percentage						24.00%			4.00%	25.00%	5.00%
Revenue Benchmark [Member] | Geographic Concentration Risk [Member] | Europe [Member]
Concentration Risk, Percentage						56.00%			48.00%	52.00%	42.00%
Revenue Benchmark [Member] | Geographic Concentration Risk [Member] | Asia [Member]
Concentration Risk, Percentage						20.00%			47.00%	23.00%	53.00%
Assets, Total [Member] | Geographic Concentration Risk [Member] | UNITED STATES
Concentration Risk, Percentage										26.00%		19.00%
Assets, Total [Member] | Geographic Concentration Risk [Member] | Non-US [Member]
Concentration Risk, Percentage										74.00%		81.00%
Paycheck Protection Program CARES Act [Member]
Proceeds from Issuance of Long-term Debt, Total			$ 2,815,200
Public Offering [Member]
Proceeds from Issuance of Equity Net				$ 13,500,000
Public Offering [Member] | Subsequent Event [Member]
Proceeds from Issuance of Equity Net	$ 13,700,000
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio					13