Note 13 - Equity-based Compensation - Weighted-average Assumptions Used in Determining the Value of Options Granted to Employees and Directors (Details) - Employees and Directors [Member] - $ / shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Expected price volatility	164.31%	159.81%
Sales and marketing (Year)	6 years 2 months 8 days	6 years 5 months 4 days
Risk-free interest rate	1.09%	0.50%
Dividend yield	0.00%	0.00%
Weighted-average fair value of options granted during the period (in dollars per share)	$ 0.90	$ 0.93