Note 5 - Debt Securities - Investments Classified by Contractual Maturity Date (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Due in one year or less, amortized cost	$ 43,819
Due in one year or less, estimated fair value	42,123
Due from one to five years, amortized cost	85,057
Due from one to five years, estimated fair value	80,169
Due from five to ten years, amortized cost	73,253
Due from five to ten years, estimated fair value	66,365
Due after ten years, amortized cost	252,938
Due after ten years, estimated fair value	216,544
Total amortized cost	455,067	$ 398,643
Total estimated fair value	$ 405,201	$ 401,103