Note 3 - Liquidity Risks and Management's Plans (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		12 Months Ended
	Mar. 25, 2021	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Sep. 17, 2020
Net Income (Loss) Attributable to Parent, Total				$ (67,636)	$ (32,566)
Impairment of Intangible Assets (Excluding Goodwill), Total		$ 7,200	$ 37,800	45,020	0
Deferred Income Tax Expense (Benefit), Total				(9,987)	0
Retained Earnings (Accumulated Deficit), Ending Balance		$ (785,324)		$ (785,324)	(717,688)
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)
Proceeds from Issuance of Common Stock				$ 4,843	0
Cash and Cash Equivalents, at Carrying Value, Ending Balance		$ 22,348		22,348	16,930
Liabilities, Current, Total		$ 4,923		$ 4,923	$ 6,131
March 2021 Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)	$ 3.60
Warrants and Rights Outstanding, Term (Year)	5 years
March 2021 Public Offering [Member]
Proceeds from Issuance or Sale of Equity, Total	$ 27,400
Equity Issued During Period, Units, New Issues (in shares)	9,230,500
Stock and Warrants Issued, Price Per Share (in dollars per share)	$ 3.25
Units, Number of Securities Called by Each Unit (in shares)	1
Units, Number of Warrants Called by Each Unit (in shares)	1
ATM Program [Member]
Shares Authorized to Be Offered and Sold Under Offering Agreement, Value						$ 10,000
Stock Issued During Period, Shares, New Issues (in shares)				2,116,944
Stock Issued During Period, Value, New Issues				$ 5,000
Proceeds from Issuance of Common Stock				4,800
Rostafuroxin Drug Candidate [Member]
Impairment of Intangible Assets (Excluding Goodwill), Total				45,000
Deferred Income Tax Expense (Benefit), Total				$ (10,000)