Note 10 - Stockholders' Equity - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Granted, shares (in shares)	441,430
Nonvested, shares (in shares)	796,264	706,980
The 2011 and 2017 Plans [Member]
Balance, shares (in shares)	4,418,681
Balance, weighted average exercise price (in dollars per share)	$ 51.7
Outstanding, weighted average remaining contractual term (Year)	5 years 6 months	5 years 2 months 12 days
Outstanding, aggregate intrinsic value	$ 2,202	$ 1,105
Granted, shares (in shares)	441,430
Granted, weighted average exercise price (in dollars per share)	$ 6.33
Granted, weighted average remaining contractual term (Year)	9 years 10 months 24 days
(Expired), shares (in shares)	(83,185)
(Expired), weighted average exercise price (in dollars per share)	$ 107.03
Balance, shares (in shares)	4,776,926	4,418,681
Balance, weighted average exercise price (in dollars per share)	$ 46.54	$ 51.7
Nonvested, shares (in shares)	796,264
Nonvested, weighted average exercise price (in dollars per share)	$ 5.5
Nonvested, weighted average remaining contractual term (Year)	9 years 4 months 24 days
Nonvested, aggregate intrinsic value	$ 373
Exercisable, shares (in shares)	3,980,662
Exercisable, weighted average exercise price (in dollars per share)	$ 54.76
Exercisable, weighted average remaining contractual term (Year)	4 years 8 months 12 days
Exercisable, aggregate intrinsic value	$ 1,829