Note 4 - Investments - Details of Marketable Securities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Fair value	$ 19	$ 22
Basis	34	34
Cumulative unrealized (loss) gain	(15)	(12)
Equity Securities [Member]
Fair value	19	22
Basis	34	34
Cumulative unrealized (loss) gain	$ (15)	$ (12)