Note 5 - Investments, Available-for-sale - Summary of Investment Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Amortized Cost	$ 995	$ 3,981
Unrealized Gain	0	0
Unrealized Loss	(1)	(10)
Fair Value	994	3,971
Short-term investments	994	3,971
Corporate Debt Securities [Member]
Amortized Cost	995	3,981
Unrealized Gain	0	0
Unrealized Loss	(1)	(10)
Fair Value	994	3,971
Short-term investments	$ 994	$ 3,971