Note 8 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended		3 Months Ended			9 Months Ended
	Mar. 25, 2021	Mar. 23, 2021	Sep. 17, 2020	Nov. 10, 2022	Oct. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Jun. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Nov. 03, 2022
Stock Issued During Period, Value, New Issues						$ 1,535	$ 1,020	$ 1,120
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
ATM Program [Member]
Shares Authorized to Be Offered and Sold Under Offering Agreement, Value			$ 10,000
Commission Fee, Percent Fee			3.00%
Stock Issued During Period, Shares, New Issues (in shares)									4,377,785	552,474
Stock Issued During Period, Value, New Issues									$ 2,800	$ 1,700
Stock Offering Agreement, Public Float Limitation Amount						$ 75,000			$ 75,000
ATM Program [Member] | Subsequent Event [Member]
Stock Issued During Period, Shares, New Issues (in shares)				5,963,408
Stock Issued During Period, Value, New Issues				$ 1,500	$ 5,963,408,000
Stock Offering Agreement, Public Float Limitation Amount											$ 75,000
March 2021 Public Offering [Member]
Equity Issued During Period, Units, New Issues (in shares)		9,230,500
Units, Number of Securities Called by Each Unit (in shares)		1
Stock and Warrants Issued, Price Per Share (in dollars per share)	$ 3.25
Proceeds from Issuance or Sale of Equity, Gross Amount	$ 30,000
Proceeds from Issuance or Sale of Equity, Total	$ 27,400