Note 1 - Business and Basis of Presentation (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Jul. 18, 2014 USD ($)
Number of Subsidiaries	1
Upfront License Fee	$ 7,000
Milestone Payments Maximum Amount	287,300			$ 187,500
Acquired In-process Research and Development	0	$ 7,000	$ 0
Net Income (Loss) Attributable to Parent	21,591	2	(29,126)
Net Cash Provided by (Used in) Operating Activities	27,009	$ (15,827)	$ 20,650
Cash, Cash Equivalents, and Marketable Securities	$ 95,900