Note 7 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended		91 Months Ended
	Aug. 31, 2020	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Dec. 31, 2023	Nov. 30, 2016
Dividends, Preferred Stock		$ 1,150	$ 1,083	$ 2,287	$ 2,155
Preferred Stock, Shares Outstanding (in shares)		62,000		62,000		62,000	62,000
Convertible Preferred Stock, Shares Reserved for Future Issuance (in shares)		8,200,000		8,200,000		8,200,000
Series A Redeemable Convertible Preferred Stock [Member]
Temporary Equity, Shares Issued (in shares)		62,000		62,000		62,000	62,000
Deferred Offering Costs		$ 2,100		$ 2,100		$ 2,100
Dividends, Preferred Stock		$ 1,200	1,100	$ 2,300	2,200
Preferred Stock, Shares Outstanding (in shares)		62,000		62,000		62,000
Series A Redeemable Convertible Preferred Stock [Member] | Private Placement [Member]
Temporary Equity, Shares Issued (in shares)	85,000
Shares Issued, Price Per Share (in dollars per share)	$ 1,000
Proceeds from Issuance of Preferred Stock and Preference Stock	$ 85,000
Preferred Stock, Dividend Rate, Percentage	6.00%
Convertible Preferred Stock, Conversion Price (in dollars per share)	$ 9.5
Common Stock [Member]
Dividends, Preferred Stock			$ (0)	$ (0)	$ (0)
Stock and Warrant Repurchase Plan [Member]
Share Repurchase Program, Authorized, Amount								$ 35,000
Warrants Repurchased During Period (in shares)						6,011,926
Warrants Repurchased During Period, Value						$ 14,700
Share Repurchase Program, Remaining Authorized, Amount		$ 12,000		$ 12,000		$ 12,000
Stock and Warrant Repurchase Plan [Member] | Common Stock [Member]
Stock Repurchased During Period, Shares (in shares)						875,218
Stock Repurchased During Period, Value						$ 8,300