Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands		12 Months Ended
	Jul. 28, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Retained Earnings (Accumulated Deficit)		$ (1,514,361)	$ (1,527,033)
Revenue from Contract with Customer, Excluding Assessed Tax		233,662	2,785	$ 6,689
Cash, Cash Equivalents, and Short-Term Investments		217,500
Restricted Cash and Investments		1,300
Prepaid Research and Development		4,183	$ 4,237
Commercialization Agreement With Neuraxpharm [Member]
License and Collaboration Agreements, One-time, Non-refundable Payment	$ 140,000	140,000
Briumvi Ublituximab [Member]
Revenue from Contract with Customer, Excluding Assessed Tax		92,000
Proceeds From Sales Returns		$ 0