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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, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022
Securities HTM:
Securities HTM, Amortized cost	$ 720,828		$ 683,707
Securities HTM, Allowance for Credit (Losses)	(203)	$ (203)	(203)
Securities HTM, Gross Unrealized Gains	24,827		33,429
Securities HTM, Gross Unrealized (Losses)	(49,005)		(36,654)
Securities HTM, Fair Value	696,447		680,279
Securities AFS:
Securities AFS, Amortized Cost	342,238		348,633
Securities AFS, Allowance for Credit (Losses)			(989)
Securities AFS, Gross Unrealized Gains	229		190
Securities AFS, Gross Unrealized (Losses)	(52,255)		(48,179)
Securities AFS, Fair Value	290,212		299,655
U.S. treasuries and govt. sponsored agency securities
Securities AFS:
Securities AFS, Amortized Cost	22,717		17,399
Securities AFS, Gross Unrealized Gains	11		12
Securities AFS, Gross Unrealized (Losses)	(2,627)		(2,438)
Securities AFS, Fair Value	20,101		14,973
Residential mortgage-backed and related securities
Securities AFS:
Securities AFS, Amortized Cost	60,950		65,168
Securities AFS, Gross Unrealized Gains	1
Securities AFS, Gross Unrealized (Losses)	(6,243)		(5,972)
Securities AFS, Fair Value	54,708		59,196
Municipal securities
Securities HTM:
Securities HTM, Amortized cost	719,778		682,657
Securities HTM, Allowance for Credit (Losses)	(202)	(202)	(202)	$ (180)	$ (180)	$ (180)
Securities HTM, Gross Unrealized Gains	24,827		33,385
Securities HTM, Gross Unrealized (Losses)	(48,989)		(36,639)
Securities HTM, Fair Value	695,414		679,201
Securities AFS:
Securities AFS, Amortized Cost	205,340		206,566
Securities AFS, Gross Unrealized Gains			11
Securities AFS, Gross Unrealized (Losses)	(40,072)		(35,590)
Securities AFS, Fair Value	165,268		170,987
Asset-backed securities
Securities AFS:
Securities AFS, Amortized Cost	12,516		15,261
Securities AFS, Gross Unrealized Gains	205		167
Securities AFS, Gross Unrealized (Losses)			(5)
Securities AFS, Fair Value	12,721		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)	(16)		(15)
Securities HTM, Fair Value	1,033		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	12
Securities AFS, Gross Unrealized (Losses)	(3,313)		(4,174)
Securities AFS, Fair Value	$ 37,414		$ 39,076