Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands		3 Months Ended					6 Months Ended
	Jul. 28, 2023	Jun. 30, 2024	Dec. 31, 2023		Sep. 30, 2023	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Retained Earnings (Accumulated Deficit)		$ (1,556,405)	$ (1,552,577)	[1]			$ (1,556,405)
Revenue from Contract with Customer, Excluding Assessed Tax		73,466				$ 16,074	136,939	$ 23,877
Cash, Cash Equivalents, and Short-Term Investments		$ 217,300					217,300
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							123,100
Proceeds From Sales Returns							$ 0

[1] Amounts as of December 31, 2023 have been reclassified to conform to current period presentation.