Note 3 - Fair Value of Financial Instruments (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Impairment of Marketable Securities	$ 0	$ 0
Fair Value, Level 1, 2 and 3 Transfers, Amount	0	0
Assets, Fair Value Disclosure	41,184	57,973
Fair Value, Recurring [Member]
Liabilities, Fair Value Disclosure	0	0
Assets, Fair Value Disclosure	$ 0	$ 0