Note 10 - Stock-based Compensation - Stock Options Outstanding (Details) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($) $ / shares shares
Options, Exercisable, Number of Shares (in shares) | shares	4,843,264
Options, Exercisable, Weighted Average Exercise Price (in dollars per share) | $ / shares (in dollars per share) | $ / shares	$ 5.96
Options, Exercisable, Weighted Average Remaining Contractual Term (Year)	4 years 9 months 18 days
Options, Exercisable, Aggregate Intrinsic Value | $	$ 0.4
Options, Vested and Expected to Vest, Exercisable, Number of Shares (in shares) | shares	9,645,630
Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 3.47
Options, Vested and Expected to Vest, Exercisable, Weighted Average Remaining Contractual Term (Year)	5 years 5 months 19 days
Options, Vested or Expected to Vest, Aggregate Intrinsic Value | $	$ 0.6