Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands		3 Months Ended			12 Months Ended
	Jul. 28, 2023	Mar. 31, 2024	Sep. 30, 2023	Mar. 31, 2023	Dec. 31, 2023
Retained Earnings (Accumulated Deficit)		$ (1,525,068)			$ (1,514,361)
Revenue from Contract with Customer, Excluding Assessed Tax		63,474		$ 7,803
Cash, Cash Equivalents, and Short-Term Investments		209,800
Commercialization Agreement With Neuraxpharm [Member]
License and Collaboration Agreements, One-time, Non-refundable Payment	$ 140,000		$ 140,000		$ 140,000
Briumvi Ublituximab [Member]
Revenue from Contract with Customer, Excluding Assessed Tax		50,500
Proceeds From Sales Returns		$ 0