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, 2022		Sep. 30, 2022		Jun. 30, 2022		Mar. 31, 2022		Dec. 31, 2021		Sep. 30, 2021		Jun. 30, 2021		Mar. 31, 2021		Dec. 31, 2022	Dec. 31, 2021
General and administrative expense	$ 1,035		$ 1,360		$ 1,146		$ 1,234		$ 1,135		$ 1,564		$ 1,991		$ 2,463		$ 4,775	$ 7,153
Operating loss	(1,035)		(1,360)		(1,146)		(1,234)		(1,135)		(1,564)		(1,991)		(2,463)		(4,775)	(7,153)
Other income (loss), net	(318)		(1,012)		30		(1,997)		(5,992)		20,588		6,733		706		(3,297)	22,035
Interest income	318		230		145		101		79		70		74		53		794	276
Equity income (loss), net	(3,838)		(1,022)		1,454		(3,579)		(1,586)		(761)		(5,136)		19,329		(6,985)	11,846
Net loss before income taxes	(4,873)		(3,164)		483		(6,709)		(8,634)		18,333		(320)		17,625		(14,263)	27,004
Net income (loss)	$ (4,873)		$ (3,164)		$ 483		$ (6,709)		$ (8,634)		$ 18,333		$ (320)		$ 17,625		$ (14,263)	$ 27,004
Basic (in dollars per share)	$ (0.30)	[1]	$ (0.19)	[1]	$ 0.03	[1]	$ (0.40)	[1]	$ (0.51)	[1]	$ 0.88	[1]	$ (0.02)	[1]	$ 0.84	[1]	$ (0.87)	$ 1.36
Diluted (in dollars per share)	$ (0.30)	[1]	$ (0.19)	[1]	$ 0.03	[1]	$ (0.40)	[1]	$ (0.51)	[1]	$ 0.88	[1]	$ (0.02)	[1]	$ 0.84	[1]	$ (0.87)	$ 1.36

[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.