Note 9 - Equity Transactions - Common Stock Warrants Outstanding (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Warrants outstanding (in shares)	2,048,186	3,662,661
Issued (in shares)	0	0
Exercised (in shares)	0	(1,599,204)
Expired (in shares)	(2,340)	(15,271)
Warrants outstanding (in shares)	2,045,846	2,048,186