Note 9 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended			3 Months Ended	6 Months Ended
	Aug. 04, 2022	Jun. 30, 2024	Apr. 30, 2024	Jan. 31, 2024	Jun. 30, 2024	Jun. 30, 2024	Jun. 30, 2023	Jun. 11, 2024	Mar. 31, 2024	Dec. 31, 2023
Preferred Stock, Shares Authorized (in shares)		5,000,000			5,000,000	5,000,000				5,000,000
Preferred Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.0001			$ 0.0001	$ 0.0001				$ 0.0001
Preferred Stock, Shares Outstanding, Ending Balance (in shares)		0			0	0				0
Common Stock, Shares Authorized (in shares)		350,000,000			350,000,000	350,000,000		350,000,000	250,000,000	250,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)		$ 0.0001			$ 0.0001	$ 0.0001				$ 0.0001
Common Stock, Increase in Shares Authorized (in shares)	100,000,000
Dividends, Total						$ 0
Treasury Stock, Common, Shares (in shares)		688,331			688,331	688,331				507,020
Class of Warrant or Right, Expirations in Period (in shares)			70,663
Warrants Expiring March 2025 [Member]
Warrant Exercise Price to be Entitled to Receive Cash Consideration, Fundamental Transaction (in dollars per share)		$ 2.5			$ 2.5	$ 2.5
Warrants Expiring February 2025 [Member]
Warrant Exercise Price to be Entitled to Receive Cash Consideration, Fundamental Transaction (in dollars per share)		$ 3.125			3.125	3.125
June 2024 Offering [Member]
Stock Issued During Period, Shares, New Issues (in shares)		50,000,000
Shares Issued, Price Per Share (in dollars per share)		$ 0.8			$ 0.8	$ 0.8
Stock Issued During Period, Value, New Issues		$ 40,000			$ 37,555	$ 37,555
Proceeds from Issuance of Common Stock		$ 37,600				37,555	$ 0
RA Capital Healthcare Fund 2024 [Member]
Stock Issued During Period, Shares, New Issues (in shares)				15,384,615
Shares Issued, Price Per Share (in dollars per share)				$ 0.65
Stock Issued During Period, Value, New Issues					$ 0	9,945
Proceeds from Issuance of Common Stock				$ 9,900		$ 9,945	$ 0
Gross Proceeds from Issuance of Common Stock				$ 10,000