Note 2 - Summary of Significant Accounting Policies - Outstanding Stock Options and Stock Warrants Excluded from the Diluted Net Loss Per Share Computation (Details) - shares shares in Thousands	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Anti-dilutive securities (in shares)	2,427	1,400
Share-Based Payment Arrangement, Option [Member]
Anti-dilutive securities (in shares)	121	126
Warrant [Member]
Anti-dilutive securities (in shares)	2,306	1,274

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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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration