Note 5 - Operating Lease Right-of-use Asset, Net (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating Lease, Expense	$ 150,000	$ 150,000	$ 301,000	$ 301,000
Operating Lease, Payments	$ 162,000	$ 158,000	$ 324,000	$ 315,000
Operating Lease, Weighted Average Remaining Lease Term (Year)	6 months		6 months
Operating Lease, Weighted Average Discount Rate, Percent	12.05%		12.05%