Note 6 - Investment Securities - Amortized Cost and Estimated Fair Value of Securities by Contractual Maturity ( (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Due in one year or less	$ 720
Due in one year or less	663
Due in one year or less	0
Due in one year or less	0
Due after one year through five years	3,155
Due after one year through five years	3,076
Due after one year through five years	0
Due after one year through five years	0
Due after five years through ten years	5,275
Due after five years through ten years	5,008
Due after five years through ten years	0
Due after ten years	126,017
Due after ten years	97,457
Due after ten years	96,881
Due after ten years	91,815
Available for sale, amortized cost	239,645	$ 242,461
Available for sale, fair value	201,740	201,322
Held to maturity, amortized cost	402,237	406,590
Held to maturity, fair value	375,952	$ 375,292
Residential Mortgage-Backed Securities [Member]
Available for sale, amortized cost	91,827
Available for sale, fair value	83,144
Held to maturity, amortized cost	246,433
Held to maturity, fair value	229,613
Commercial Mortgage-Backed Securities [Member]
Available for sale, amortized cost	12,651
Available for sale, fair value	12,392
Held to maturity, amortized cost	58,923
Held to maturity, fair value	$ 54,524