Note 13 - Stock-based Compensation - Stock Option Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Options, Outstanding, Number of Shares (in shares)	4,640,660
Options, Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 6.64
Options, Outstanding, Weighted Average Remaining Contractual Term (Year)	5 years 3 months 21 days	5 years 7 months 28 days
Options, Granted, Number of Shares (in shares)	3,153,881
Options, Grants in Period, Weighted Average Exercise Price (in dollars per share)	$ 0.70
Options, Forfeited, Number of Shares (in shares)	(129,134)
Options, Forfeitures in Period, Weighted Average Exercise Price (in dollars per share)	$ 1.60
Options, Cancelled, Number of Shares (in shares)	(36,987)
Options, Expirations in Period, Weighted Average Exercise Price (in dollars per share)	$ 21.11
Options, Exercised, Number of Shares (in shares)	(43,453)
Options, Exercises in Period, Weighted Average Exercise Price (in dollars per share)	$ 0.41
Options, Outstanding, Number of Shares (in shares)	7,584,967	4,640,660
Options, Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 4.22	$ 6.64