Note 3 - Investment Securities - Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Securities HTM:
Securities held to maturity, due in one year or less, amortized cost	$ 1,876
Securities held to maturity, due in one year or less, fair value	1,867
Securities held to maturity, due after one year through five years, amortized cost	27,293
Securities held to maturity, due after one year through five years, fair value	29,060
Securities held to maturity, due after five years, amortized cost	654,538
Securities held to maturity, due after five years, fair value	649,352
Securities HTM, Amortized cost	683,707	$ 587,322
Securities held to maturity, fair value	680,279	535,636
Securities AFS:
Securities available for sale, due in one year or less, amortized cost	968
Securities available for sale, Due in one year or less, fair value	964
Securities available for sale, due after one year through five years, amortized cost	16,819
Securities available for sale, Due after one year through five years, fair value	14,815
Securities available for sale, due after five years, amortized cost	250,417
Securities available for sale, due after five years, fair value	209,257
Securities available for sale, single maturity, amortized cost	268,204
Securities available for sale, single maturity, fair value	225,036
Securities AFS, Amortized Cost	348,633	400,511
Available-for-sale Securities, Debt Securities, Total	299,655	340,960
Callable Securities [Member]
Securities AFS:
Securities AFS, Amortized Cost	248,448
Available-for-sale Securities, Debt Securities, Total	207,737
Municipal securities.
Securities HTM:
Securities HTM, Amortized cost	682,657	586,272
Securities held to maturity, fair value	679,201	534,586
Securities AFS:
Securities AFS, Amortized Cost	206,566	239,812
Available-for-sale Securities, Debt Securities, Total	170,987	193,178
Municipal securities. | Callable Securities [Member]
Securities HTM:
Securities held to maturity, callable, amortized cost	261,340
Securities held to maturity, callable, fair value	257,714
Securities AFS:
Securities available for sale, callable, amortized cost	205,165
Securities available for sale, callable, fair value	169,604
Asset-backed securities
Securities AFS:
Securities AFS, Amortized Cost	15,261	18,885
Available-for-sale Securities, Debt Securities, Total	15,423	18,728
Securities available for sale, callable, amortized cost	15,261
Securities available for sale, callable, fair value	15,423
Residential mortgage-backed and related securities
Securities AFS:
Securities AFS, Amortized Cost	65,168	73,438
Available-for-sale Securities, Debt Securities, Total	59,196	66,215
Securities available for sale, callable, amortized cost	65,168
Securities available for sale, callable, fair value	59,196
Other securities
Securities HTM:
Securities HTM, Amortized cost	1,050	1,050
Securities held to maturity, fair value	1,078	1,050
Securities AFS:
Securities AFS, Amortized Cost	44,239	48,631
Available-for-sale Securities, Debt Securities, Total	39,076	$ 45,858
Other securities | Callable Securities [Member]
Securities AFS:
Securities available for sale, callable, amortized cost	43,283
Securities available for sale, callable, fair value	$ 38,133