Note 3 - Investment Securities - Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Securities available for sale, amortized cost, due in one year or less	$ 65,774
Securities available for sale, fair value, due in one year or less	64,401
Securities held to maturity, amortized cost, due in one year or less	0
Securities held to maturity, fair value, due in one year or less	0
Securities available for sale, amortized cost, due after one year through five years	177,859
Securities available for sale, fair value, due after one year through five years	163,024
Securities held to maturity, amortized cost, due after one year through five years	0
Securities held to maturity, fair value, due after one year through five years	0
Securities available for sale, amortized cost, due after five years through ten years	45,517
Securities available for sale, fair value, due after five years through ten years	41,252
Securities held to maturity, amortized cost, due after five years through ten years	2,000
Securities held to maturity, fair value, due after five years through ten years	1,291
Securities available for sale, amortized cost, due after ten years	92,213
Securities available for sale, fair value, due after ten years	76,515
Securities held to maturity, amortized cost, due after ten years	5,000
Securities held to maturity, fair value, due after ten years	3,181
Securities available for sale, amortized cost, single maturity	381,363
Securities available for sale, fair value, single maturity	345,192
Securities held to maturity, amortized cost, single maturity	7,000
Securities held to maturity, fair value, single maturity	4,472
Mortgage-backed securities and CMO, amortized cost	107,824
Mortgage-backed securities and CMO, fair value	94,888
Mortgage-backed securities and CMO, amortized cost	0
Mortgage-backed securities and CMO, fair value	0
Securities available for sale, amortized cost	489,187	$ 507,466
Securities available for sale, fair value	440,080	460,819
Securities held to maturity, amortized cost	7,000	7,000
Securities held to maturity, fair value	$ 4,472	$ 5,311