Note 6 - Liabilities Related to Sale of Future Royalties - Deferred Revenue Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Current portion	$ (2,360)	$ (3,803)
Long-term portion	1,863	$ 2,623
HealthCare Royalty Partners III, L.P. [Member] | Royalty Arrangement [Member]
Total liability related to sale of future royalties, start of period	6,426
Non-cash royalty revenue paid to HCRP	(3,007)
Non-cash interest expense recognized	804
Total liability related to sale of future royalties, end of period	4,223
Current portion	(2,360)
Long-term portion	$ 1,863