Note 3 - Liquidity Risks and Management's Plans (Details Textual) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		4 Months Ended
	Mar. 31, 2022	Apr. 30, 2022	Mar. 31, 2022	Mar. 31, 2021	Apr. 30, 2022	Dec. 31, 2021
Net Income (Loss) Attributable to Parent, Total			$ (8,127)	$ (8,961)
Retained Earnings (Accumulated Deficit), Total	$ (793,451)		(793,451)			$ (785,324)
Proceeds from Issuance of Common Stock			205	$ 570
Cash and Cash Equivalents, at Carrying Value, Total	15,541		$ 15,541			$ 22,348
ATM Program [Member]
Stock Issued During Period, Shares, New Issues (in shares)			200,348	105,083
Stock Issued During Period, Value, New Issues			$ 200	$ 600
Proceeds from Issuance of Common Stock	$ 4,800
ATM Program [Member] | Subsequent Event [Member]
Stock Issued During Period, Shares, New Issues (in shares)		936,898			936,898
Stock Issued During Period, Value, New Issues		$ 1,100
Proceeds from Issuance of Common Stock		$ 1,000
Rostafuroxin Drug Candidate [Member]
Deferred Income Tax Expense (Benefit), Total			$ (10,000)