Note 3 - Debt and Equity Securities - Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Due in one year or less, securities available-for-sale, amortized cost	$ 5,455
Due in one year or less, securities available-for-sale, estimated market value	5,277
Due after one year through five years, securities available-for-sale, amortized cost	85,654
Due after one year through five years, securities available-for-sale, estimated market value	78,157
Due after five years through ten years, securities available-for-sale, amortized cost	271,526
Due after five years through ten years, securities available-for-sale, estimated market value	226,693
Due after ten years, securities available-for-sale, amortized cost	632,480
Due after ten years, securities available-for-sale, estimated market value	529,025
Securities available-for-sale, amortized cost	995,115	$ 906,135
Securities available-for-sale, estimated market value	$ 839,152	$ 897,585

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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