Note 3 - Investments in Debt Securities - Maturities of Debt Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
One year or less, amortized cost	$ 1,573	$ 2,687
One year or less, fair value	1,574	2,692
Greater than one year through five years, amortized cost	0	0
Greater than one year through five years, fair value	0	0
Amortized cost	1,573	2,687
Estimated fair value	$ 1,574	$ 2,692