Note 11 - Stockholders' Equity (Deficit) - Stock Options Rollforward (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Nonvested shares (in shares)	835,297	899,672
Nonvested, Beginning balance, Weighted Average Grant-Date Fair Value (in dollars per share)	$ 7.76	$ 8.71
Granted, shares (in shares)	582,353	640,748
Granted, Weighted Average Grant-Date Fair Value (in dollars per share)	$ 1.72	$ 7.90	$ 7.81
Vested/Issued, shares (in shares)	(618,274)	(518,784)
Vested/Issued, Weighted Average Grant-Date Fair Value (in dollars per share)	$ 6.61	$ 9.51
Forfeited, shares (in shares)		(186,339)
Forfeited, Weighted Average Grant-Date Fair Value (in dollars per share)		$ 7.96
Nonvested shares (in shares)	799,376	835,297	899,672
Nonvested, Beginning balance, Weighted Average Grant-Date Fair Value (in dollars per share)	$ 4.25	$ 7.76	$ 8.71