Note 5 - Debt Securities - Investments Classified by Contractual Maturity Date (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Due in one year or less, amortized cost	$ 34,660
Due in one year or less, estimated fair value	33,530
Due from one to five years, amortized cost	80,286
Due from one to five years, estimated fair value	76,508
Due from five to ten years, amortized cost	62,393
Due from five to ten years, estimated fair value	57,655
Due after ten years, amortized cost	258,037
Due after ten years, estimated fair value	216,272
Total amortized cost	435,376	$ 398,643
Total estimated fair value	$ 383,965	$ 401,103	[1]

[1] Derived from audited consolidated financial statements