Note 3 - Investment Securities - Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Securities HTM:
Securities held to maturity, due in one year or less, amortized cost	$ 2,902
Securities held to maturity, due in one year or less, fair value	2,895
Securities held to maturity, due after one year through five years, amortized cost	18,998
Securities held to maturity, due after one year through five years, fair value	19,359
Securities held to maturity, due after five years, amortized cost	565,422
Securities held to maturity, due after five years, fair value	513,382
Securities held to maturity, amortized cost	587,322
Securities held to maturity, fair value	535,636	$ 522,297
Securities AFS:
Securities available for sale, due in one year or less, amortized cost	4,522
Securities available for sale, Due in one year or less, fair value	4,510
Securities available for sale, due after one year through five years, amortized cost	4,159
Securities available for sale, Due after one year through five years, fair value	4,135
Securities available for sale, due after five years, amortized cost	299,507
Securities available for sale, due after five years, fair value	247,372
Securities available for sale, single maturity, amortized cost	308,188
Securities available for sale, single maturity, fair value	256,017
Securities AFS, Amortized Cost	400,511	329,994
Available-for-sale Securities, Debt Securities, Total	340,960	337,830
Securities available for sale, callable, amortized cost	400,511
Securities available for sale, callable, fair value	340,960
Callable Securities [Member]
Securities AFS:
Securities AFS, Amortized Cost	283,015
Available-for-sale Securities, Debt Securities, Total	233,630
Municipal securities.
Securities HTM:
Securities held to maturity, fair value	534,586	521,248
Securities AFS:
Securities AFS, Amortized Cost	239,812	163,253
Available-for-sale Securities, Debt Securities, Total	193,178	168,266
Municipal securities. | Callable Securities [Member]
Securities HTM:
Securities held to maturity, callable, amortized cost	330,576
Securities held to maturity, callable, fair value	296,851
Securities AFS:
Securities available for sale, callable, amortized cost	235,334
Securities available for sale, callable, fair value	188,707
Asset-backed securities
Securities AFS:
Securities AFS, Amortized Cost	18,885	26,372
Available-for-sale Securities, Debt Securities, Total	18,728	27,124
Securities available for sale, callable, amortized cost	18,885
Securities available for sale, callable, fair value	18,728
Residential mortgage-backed and related securities
Securities AFS:
Securities AFS, Amortized Cost	73,438	92,431
Available-for-sale Securities, Debt Securities, Total	66,215	94,323
Securities available for sale, callable, amortized cost	73,438
Securities available for sale, callable, fair value	66,215
Other securities
Securities HTM:
Securities held to maturity, fair value	1,050	1,049
Securities AFS:
Securities AFS, Amortized Cost	48,631	24,568
Available-for-sale Securities, Debt Securities, Total	45,858	$ 24,789
Other securities | Callable Securities [Member]
Securities AFS:
Securities available for sale, callable, amortized cost	47,681
Securities available for sale, callable, fair value	$ 44,923