Note 2 - Investment Securities - Amortized Cost and Fair Value of HTM and AFS Investment Securities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Securities HTM:
Securities HTM, Amortized cost	$ 836,060	$ 683,707
Securities held to maturity, at amortized cost, net of allowance for credit losses	835,797	683,504
Securities HTM, Allowance for Credit (Losses)	263	203	$ 180
Securities HTM, Gross Unrealized Gains	27,957	33,429
Securities HTM, Gross Unrealized (Losses)	(63,171)	(36,654)
Securities HTM, Fair Value	800,583	680,279
Securities AFS:
Securities AFS, Amortized Cost	331,337	348,633
Securities AFS, Allowance for Credit (Losses)		(989)
Securities AFS, Gross Unrealized Gains	185	190
Securities AFS, Gross Unrealized (Losses)	(50,413)	(48,179)
Securities AFS, Fair Value	281,109	299,655
U.S. treasuries and govt. sponsored agency securities
Securities AFS:
Securities AFS, Amortized Cost	23,113	17,399
Securities AFS, Gross Unrealized Gains	7	12
Securities AFS, Gross Unrealized (Losses)	(2,529)	(2,438)
Securities AFS, Fair Value	20,591	14,973
Residential mortgage-backed and related securities
Securities AFS:
Securities AFS, Amortized Cost	55,641	65,168
Securities AFS, Gross Unrealized Gains	3
Securities AFS, Gross Unrealized (Losses)	(5,602)	(5,972)
Securities AFS, Fair Value	50,042	59,196
Municipal securities
Securities HTM:
Securities HTM, Amortized cost	806,992	682,657
Securities HTM, Allowance for Credit (Losses)	254	202	$ 180
Securities HTM, Gross Unrealized Gains	23,292	33,385
Securities HTM, Gross Unrealized (Losses)	(63,164)	(36,639)
Securities HTM, Fair Value	766,866	679,201
Securities AFS:
Securities AFS, Amortized Cost	204,664	206,566
Securities AFS, Gross Unrealized Gains		11
Securities AFS, Gross Unrealized (Losses)	(40,089)	(35,590)
Securities AFS, Fair Value	164,575	170,987
Asset-backed securities
Securities AFS:
Securities AFS, Amortized Cost	9,053	15,261
Securities AFS, Gross Unrealized Gains	171	167
Securities AFS, Gross Unrealized (Losses)		(5)
Securities AFS, Fair Value	9,224	15,423
Corporate securities
Securities HTM:
Securities HTM, Amortized cost	28,018
Securities HTM, Allowance for Credit (Losses)	8
Securities HTM, Gross Unrealized Gains	4,665
Securities HTM, Fair Value	32,675
Securities AFS:
Securities AFS, Amortized Cost	38,866	44,239
Securities AFS, Allowance for Credit (Losses)		(989)
Securities AFS, Gross Unrealized Gains	4
Securities AFS, Gross Unrealized (Losses)	(2,193)	(4,174)
Securities AFS, Fair Value	36,677	39,076
Other securities
Securities HTM:
Securities HTM, Amortized cost	1,050	1,050
Securities HTM, Allowance for Credit (Losses)	1	1
Securities HTM, Gross Unrealized Gains		44
Securities HTM, Gross Unrealized (Losses)	(7)	(15)
Securities HTM, Fair Value	$ 1,042	$ 1,078

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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