Note 4 - Investment Securities - Summary of Amortized Cost and Fair Value by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Due in one year or less	$ 0
Due in one year or less	0
Due after one year through five years	29,242
Due after one year through five years	27,031
Due after five years through ten years	72,477
Due after five years through ten years	63,523
Due after ten years	122,893
Due after ten years	103,419
Total held-to-maturity securities	224,612
Total held-to-maturity securities	193,973
Due in one year or less	2,748
Due in one year or less	2,666
Due after one year through five years	30,408
Due after one year through five years	27,307
Due after five years through ten years	24,939
Due after five years through ten years	21,109
Due after ten years	109,807
Due after ten years	97,421
MBS - GSE residential, amortized cost	220,189
MBS - GSE residential, fair value	185,901
Total available-for-sale debt securities	388,091
Total available-for-sale debt securities, fair value	$ 334,404	$ 344,040