Note 4 - Realized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Gross realized gains	$ 0	$ 0	$ 8
Gross realized losses	(1,096)	(2,058)	(147)
Impairment	0	0	0
Total net losses on available-for-sale securities	$ (1,096)	$ (2,058)	$ (139)