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Note 2 - INVESTMENT SECURITIES - Amortized Cost and Fair Value of Investment Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Jun. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021
Securities HTM:
Securities HTM, Amortized cost	$ 615,295		$ 587,322
Securities HTM, Allowance for Credit (Losses)	(180)		(180)
Securities HTM, Gross Unrealized Gains	2,448		5,292
Securities HTM, Gross Unrealized (Losses)	(92,744)		(56,798)
Securities HTM, Fair Value	524,819		535,636
Securities AFS:
Securities AFS, Amortized Cost	355,638		400,511
Securities AFS, Allowance for Credit (Losses)	(989)
Securities AFS, Gross Unrealized Gains	159		160
Securities AFS, Gross Unrealized (Losses)	(73,529)		(59,711)
Securities AFS, Fair Value	281,279		340,960
U.S. treasuries and govt. sponsored agency securities
Securities AFS:
Securities AFS, Amortized Cost	19,130		19,745
Securities AFS, Gross Unrealized Gains	13		19
Securities AFS, Gross Unrealized (Losses)	(3,141)		(2,783)
Securities AFS, Fair Value	16,002		16,981
Residential mortgage-backed and related securities
Securities AFS:
Securities AFS, Amortized Cost	66,433		73,438
Securities AFS, Gross Unrealized (Losses)	(8,487)		(7,223)
Securities AFS, Fair Value	57,946		66,215
Municipal securities.
Securities HTM:
Securities HTM, Amortized cost	614,245		586,272
Securities HTM, Allowance for Credit (Losses)	(180)	$ (180)	(180)	$ (198)	$ (198)	$ (198)
Securities HTM, Gross Unrealized Gains	2,448		5,292
Securities HTM, Gross Unrealized (Losses)	(92,718)		(56,798)
Securities HTM, Fair Value	523,795		534,586
Securities AFS:
Securities AFS, Amortized Cost	207,318		239,812
Securities AFS, Gross Unrealized Gains			66
Securities AFS, Gross Unrealized (Losses)	(57,546)		(46,700)
Securities AFS, Fair Value	149,772		193,178
Asset-backed securities
Securities AFS:
Securities AFS, Amortized Cost	16,226		18,885
Securities AFS, Gross Unrealized Gains	144		48
Securities AFS, Gross Unrealized (Losses)	(44)		(205)
Securities AFS, Fair Value	16,326		18,728
Corporate Debt Securities [Member]
Securities AFS:
Securities AFS, Allowance for Credit (Losses)	(989)	$ (989)
Other securities
Securities HTM:
Securities HTM, Amortized cost	1,050		1,050
Securities HTM, Gross Unrealized (Losses)	(26)
Securities HTM, Fair Value	1,024		1,050
Securities AFS:
Securities AFS, Amortized Cost	46,531		48,631
Securities AFS, Allowance for Credit (Losses)	(989)
Securities AFS, Gross Unrealized Gains	2		27
Securities AFS, Gross Unrealized (Losses)	(4,311)		(2,800)
Securities AFS, Fair Value	$ 41,233		$ 45,858