Note 14 - Selected Quarterly Financial Information (Unaudited) - Schedule of Selected Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2023		Sep. 30, 2023		Jun. 30, 2023		Mar. 31, 2023		Dec. 31, 2022		Sep. 30, 2022		Jun. 30, 2022		Mar. 31, 2022		Dec. 31, 2023	Dec. 31, 2022
General and administrative expense	$ 1,999		$ 1,313		$ 1,186		$ 1,185		$ 1,035		$ 1,360		$ 1,146		$ 1,234		$ 5,683	$ 4,775
Operating loss	(1,999)		(1,313)		(1,186)		(1,185)		(1,035)		(1,360)		(1,146)		(1,234)		(5,683)	(4,775)
Other income (loss), net	551		1,661		(166)		(9)		(318)		(1,012)		30		(1,997)		2,037	(3,297)
Interest income	182		198		249		274		318		230		145		101		903	794
Equity income (loss), net	(3,148)		386		(1,759)		(2,564)		(3,838)		(1,022)		1,454		(3,579)		(7,085)	(6,985)
Net income (loss) before income taxes	(4,414)		932		(2,862)		(3,484)		(4,873)		(3,164)		483		(6,709)		(9,828)	(14,263)
Net income (loss)	$ (4,414)		$ 932		$ (2,862)		$ (3,484)		$ (4,873)		$ (3,164)		$ 483		$ (6,709)		$ (9,828)	$ (14,263)
Basic (in dollars per share)	$ (0.27)	[1]	$ 0.06	[1]	$ (0.18)	[1]	$ (0.22)	[1]	$ (0.3)	[1]	$ (0.19)	[1]	$ 0.03	[1]	$ (0.4)	[1]	$ (0.61)	$ (0.87)
Diluted (in dollars per share)	$ (0.27)	[1]	$ 0.06	[1]	$ (0.18)	[1]	$ (0.22)	[1]	$ (0.3)	[1]	$ (0.19)	[1]	$ 0.03	[1]	$ (0.4)	[1]	$ (0.61)	$ (0.87)

[1] Per share amounts for the quarters have each been calculated separately. Accordingly, quarterly amounts may not add to the annual amounts because of differences in the average common shares outstanding during each period. Additionally, in regard to diluted per share amounts only, quarterly amounts may not add to the annual amounts because of the inclusion of the effect of potentially dilutive securities only in the periods in which such effect would have been dilutive, and because of the adjustments to net income (loss) for the dilutive effect of common stock equivalents and convertible securities at our ownership interests.