Note 13 - Stock-based Compensation - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Options, Outstanding, Number of Shares (in shares)	7,584,967
Options, Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 4.22
Options, Outstanding, Weighted Average Remaining Contractual Term (Year)	4 years 9 months 18 days	5 years 3 months 21 days
Options, Granted, Number of Shares (in shares)	3,047,615
Options, Grants in Period, Weighted Average Exercise Price (in dollars per share)	$ 0.71
Options, Forfeited, Number of Shares (in shares)	(149,430)
Options, Forfeitures in Period, Weighted Average Exercise Price (in dollars per share)	$ 0.78
Options, Cancelled, Number of Shares (in shares)	(25,173)
Options, Expirations in Period, Weighted Average Exercise Price (in dollars per share)	$ 27.32
Options, Exercised, Number of Shares (in shares)	(13,300)
Options, Exercises in Period, Weighted Average Exercise Price (in dollars per share)	$ 0.38
Options, Outstanding, Number of Shares (in shares)	10,444,679	7,584,967
Options, Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 3.2	$ 4.22