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Note 2 - INVESTMENT SECURITIES - Amortized Cost and Fair Value of HTM and AFS Investment Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023
Securities HTM:
Securities HTM, Amortized Cost	$ 909,298		$ 836,060
Securities HTM, Allowance for Credit (Losses)	(263)	$ (263)	(263)	$ (203)	$ (203)	$ (203)
Securities HTM, Gross Unrealized Gains	15,194		27,957
Securities HTM, Gross Unrealized (Losses)	(120,664)		(63,171)
Securities HTM, Fair Value	803,565		800,583
Securities AFS:
Securities AFS, Amortized Cost	329,642		331,337
Securities AFS, Gross Unrealized Gains	127		185
Securities AFS, Gross Unrealized (Losses)	(58,252)		(50,413)
Securities AFS, Fair Value	271,517		281,109
U.S. treasuries and govt. sponsored agency securities
Securities AFS:
Securities AFS, Amortized Cost	16,268		23,113
Securities AFS, Gross Unrealized Gains	3		7
Securities AFS, Gross Unrealized (Losses)	(2,004)		(2,529)
Securities AFS, Fair Value	14,267		20,591
Residential mortgage-backed and related securities
Securities AFS:
Securities AFS, Amortized Cost	63,364		55,641
Securities AFS, Gross Unrealized Gains	6		3
Securities AFS, Gross Unrealized (Losses)	(4,506)		(5,602)
Securities AFS, Fair Value	58,864		50,042
Municipal securities
Securities HTM:
Securities HTM, Amortized Cost	879,663		806,992
Securities HTM, Allowance for Credit (Losses)	(254)	(254)	(254)	(202)
Securities HTM, Gross Unrealized Gains	11,203		23,292
Securities HTM, Gross Unrealized (Losses)	(120,662)		(63,164)
Securities HTM, Fair Value	769,950		766,866
Securities AFS:
Securities AFS, Amortized Cost	204,038		204,664
Securities AFS, Allowance for Credit (Losses)				(202)	(202)	(202)
Securities AFS, Gross Unrealized (Losses)	(50,059)		(40,089)
Securities AFS, Fair Value	153,979		164,575
Asset-backed securities
Securities AFS:
Securities AFS, Amortized Cost	6,599		9,053
Securities AFS, Gross Unrealized Gains	85		171
Securities AFS, Fair Value	6,684		9,224
Corporate securities
Securities HTM:
Securities HTM, Amortized Cost	28,585		28,018
Securities HTM, Allowance for Credit (Losses)	(8)	(8)	(8)
Securities HTM, Gross Unrealized Gains	3,991		4,665
Securities HTM, Fair Value	32,568		32,675
Securities AFS:
Securities AFS, Amortized Cost	39,373		38,866
Securities AFS, Allowance for Credit (Losses)						(989)
Securities AFS, Gross Unrealized Gains	33		4
Securities AFS, Gross Unrealized (Losses)	(1,683)		(2,193)
Securities AFS, Fair Value	37,723		36,677
Other securities
Securities HTM:
Securities HTM, Amortized Cost	1,050		1,050
Securities HTM, Allowance for Credit (Losses)	(1)	$ (1)	(1)	$ (1)	$ (1)	$ (1)
Securities HTM, Gross Unrealized (Losses)	(2)		(7)
Securities HTM, Fair Value	$ 1,047		$ 1,042