Note 2 - Summary of Significant Accounting Policies - Debt Securities by Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Within one year, amortized cost	$ 12,855
Within one year, fair value	12,751
After one year through two years, amortized cost	4,408
After one year through two years, fair value	4,300
After two years through three years, amortized cost	466
After two years through three years, fair value	453
Amortized cost	17,729	$ 9,341
Fair value	$ 17,504	$ 9,173