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Note 2 - INVESTMENT SECURITIES - Amortized Cost and Fair Value of HTM and AFS Investment Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022
Securities HTM:
Securities HTM, Amortized cost	$ 795,699		$ 683,707
Securities HTM, Allowance for Credit (Losses)	(203)	$ (203)	(203)
Securities HTM, Gross Unrealized Gains	34,994		33,429
Securities HTM, Gross Unrealized (Losses)	(38,831)		(36,654)
Securities HTM, Fair Value	791,659		680,279
Securities AFS:
Securities AFS, Amortized Cost	334,466		348,633
Securities AFS, Allowance for Credit (Losses)			(989)
Securities AFS, Gross Unrealized Gains	157		190
Securities AFS, Gross Unrealized (Losses)	(42,758)		(48,179)
Securities AFS, Fair Value	291,865		299,655
U.S. treasuries and govt. sponsored agency securities
Securities AFS:
Securities AFS, Amortized Cost	20,622		17,399
Securities AFS, Gross Unrealized Gains	13		12
Securities AFS, Gross Unrealized (Losses)	(2,014)		(2,438)
Securities AFS, Fair Value	18,621		14,973
Residential mortgage-backed and related securities
Securities AFS:
Securities AFS, Amortized Cost	57,924		65,168
Securities AFS, Gross Unrealized Gains	5
Securities AFS, Gross Unrealized (Losses)	(4,442)		(5,972)
Securities AFS, Fair Value	53,487		59,196
Municipal securities
Securities HTM:
Securities HTM, Amortized cost	794,649		682,657
Securities HTM, Allowance for Credit (Losses)	(202)	(202)	(202)	$ (180)	$ (180)	$ (180)
Securities HTM, Gross Unrealized Gains	34,994		33,385
Securities HTM, Gross Unrealized (Losses)	(38,831)		(36,639)
Securities HTM, Fair Value	790,610		679,201
Securities AFS:
Securities AFS, Amortized Cost	204,879		206,566
Securities AFS, Gross Unrealized Gains	5		11
Securities AFS, Gross Unrealized (Losses)	(33,722)		(35,590)
Securities AFS, Fair Value	171,162		170,987
Asset-backed securities
Securities AFS:
Securities AFS, Amortized Cost	10,326		15,261
Securities AFS, Gross Unrealized Gains	129		167
Securities AFS, Gross Unrealized (Losses)			(5)
Securities AFS, Fair Value	10,455		15,423
Other securities
Securities HTM:
Securities HTM, Amortized cost	1,050		1,050
Securities HTM, Allowance for Credit (Losses)	(1)	$ (1)	(1)
Securities HTM, Gross Unrealized Gains			44
Securities HTM, Gross Unrealized (Losses)			(15)
Securities HTM, Fair Value	1,049		1,078
Securities AFS:
Securities AFS, Amortized Cost	40,715		44,239
Securities AFS, Allowance for Credit (Losses)			(989)	(989)
Securities AFS, Gross Unrealized Gains	5
Securities AFS, Gross Unrealized (Losses)	(2,580)		(4,174)
Securities AFS, Fair Value	$ 38,140		39,076
Corporate securities
Securities AFS:
Securities AFS, Allowance for Credit (Losses)			$ (989)	$ (989)	$ (989)