Note 9 - Stockholders' Equity - Warrants (Details) - shares	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Balance, Warrants (in shares)	35,920,000	1,015,000
Warrants issued in connection with public offering and private placement (in shares)	0	0
Exercises and conversions (in shares)	0	0
Balance, Warrants (in shares)	35,920,000	1,015,000