Note 10 - Equity, Share-based Compensation, Warrants and Securities Offerings - Warrants Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Outstanding, balance (in shares)	875,067	664,592
Outstanding, weighted average exercise price (in dollars per share)	$ 9.76	$ 9.82
Nonvested, weighted average expense period (Year)	2 years 10 months 24 days	1 year 4 months 24 days	1 year 1 month 6 days
Issued (in shares)	2,063,000	230,769
Issued, weighted average exercise price (in dollars per share)	$ 1.61	$ 10.00
Issued, weighted average remaining contractual life (Year)	3 years 1 month 6 days	5 years
Before adjustment (in shares)	230,769
Before adjustment, weighted average exercise price (in dollars per share)	$ 10.00
Before adjustment, weighted average remaining contractual life (Year)	4 years
After adjustment (in shares)	(230,769)
After adjustment, weighted average exercise price (in dollars per share)	$ 2.72
After adjustment, weighted average remaining contractual life (Year)	4 years
Cash exercised (in shares)		(17,794)
Cash exercised, weighted average exercise price (in dollars per share)		$ 9.60
Cash exercised, weighted average remaining contractual life (Year)		9 months 18 days
Expired (in shares)	(639,298)	(2,500)
Expired, weighted average exercise price (in dollars per share)	$ 9.60	$ 52.50
Outstanding, balance (in shares)	2,298,769	875,067	664,592
Outstanding, weighted average exercise price (in dollars per share)	$ 1.76	$ 9.76	$ 9.82