Note 3 - Investment Securities Available for Sale - Investment Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Within one year, amortized cost	$ 1,805
Within one year, fair value	1,792
After one year through five years, amortized cost	7,350
After one year through five years, estimated fair value	7,158
After five years through ten years, amortized cost	15,464
After five years through ten years, estimated fair value	14,531
After ten years, amortized cost	67,254
After ten years, estimated fair value	57,828
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	519,540	$ 491,490
Debt Securities, Available-for-Sale, Excluding Accrued Interest	475,168	476,595
Residential Mortgage Backed Securities Issued by US Government Sponsored Enterprises [Member]
Investment securities not due at a single maturity date, amortized cost	264,595
Investment securities not due at a single maturity date, estimated fair value	246,652
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	264,595	257,520
Debt Securities, Available-for-Sale, Excluding Accrued Interest	246,652	253,165
Commercial Mortgage Backed Securities Issued by US Government Agencies [Member]
Investment securities not due at a single maturity date, amortized cost	163,072
Investment securities not due at a single maturity date, estimated fair value	147,207
Debt Securities, Available-for-Sale, Amortized Cost, Excluding Accrued Interest, before Allowance for Credit Loss	163,072	141,861
Debt Securities, Available-for-Sale, Excluding Accrued Interest	$ 147,207	$ 134,764

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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