Note 9 - Net Loss Per Share of Common Stock - Antidilutive Securities (Details) - shares	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Share-Based Payment Arrangement, Option [Member]
Anti-dilutive securities (in shares)	7,234,248	3,677,075
Common Stock Warrants [Member]
Anti-dilutive securities (in shares)	50,029,052	4,850,241
Pre-funded Warrants [Member]
Anti-dilutive securities (in shares)	0	4,545,455

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482662/260-10-50-1

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration