Note 2 - Revenue (Details Textual) - USD ($) $ in Thousands		12 Months Ended
	Jul. 28, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue from Contract with Customer, Excluding Assessed Tax		$ 233,662	$ 2,785	$ 6,689
Product [Member]
Revenue from Contract with Customer, Excluding Assessed Tax		92,005	$ 2,633	$ 6,537
Royalty [Member]
Revenue from Contract with Customer, Excluding Assessed Tax		0
Briumvi Ublituximab [Member]
Revenue from Contract with Customer, Excluding Assessed Tax		92,000
Briumvi Ublituximab [Member] | Product [Member]
Gross Net Accruals		9,200
Product Sales, Net Related to Performance Obligations		3,200
Commercialization Agreement With Neuraxpharm [Member]
License and Collaboration Agreements, One-time, Non-refundable Payment	$ 140,000	140,000
Royalty Percentage on Net Product Sales	30.00%
Revenue from Contract with Customer, Including Assessed Tax		1,500
Consideration Receivable, Performance Obligation		1,900
Deferred Revenue		$ 5,900
Commercialization Agreement With Neuraxpharm [Member] | Maximum [Member]
Qualified Sales-based Milestone Revenue	$ 505,000