Note 7 - Liabilities Related to Sale of Future Royalties - Deferred Revenue Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Current portion	$ (3,803)	$ (95)
Long-term portion	2,623	$ 5,621
HealthCare Royalty Partners III, L.P. [Member] | Royalty Arrangement [Member]
Total liability related to sale of future royalties, start of year	5,716
Non-cash royalty revenue paid to HCRP	(737)
Non-cash interest expense recognized	1,447
Total liability related to sale of future royalties, end of year	6,426
Current portion	(3,803)
Long-term portion	$ 2,623