Note 4 - Investment Securities - Securities in an Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Temporarily impaired securities, fair value	$ 598,125	$ 600,311
Temporarily impaired securities, unrealized losses	(76,383)	(70,409)
Temporarily impaired securities, fair value, less than 12 months	156,419	119,093
Temporarily impaired securities, unrealized losses, less than 12 months	(2,269)	(410)
Temporarily impaired securities, fair value, 12 months or longer	441,706	481,218
Temporarily impaired securities, unrealized losses, 12 months or longer	(74,114)	(69,999)
US Government Agencies Debt Securities [Member]
Temporarily impaired securities, fair value	77,588	135,103
Temporarily impaired securities, unrealized losses	(10,183)	(9,669)
Temporarily impaired securities, fair value, less than 12 months	45,048	101,610
Temporarily impaired securities, unrealized losses, less than 12 months	(433)	(246)
Temporarily impaired securities, fair value, 12 months or longer	32,540	33,493
Temporarily impaired securities, unrealized losses, 12 months or longer	(9,750)	(9,423)
Residential Mortgage-Backed Securities [Member]
Temporarily impaired securities, fair value	386,362	331,799
Temporarily impaired securities, unrealized losses	(45,424)	(43,058)
Temporarily impaired securities, fair value, less than 12 months	83,827	5,547
Temporarily impaired securities, unrealized losses, less than 12 months	(1,200)	(45)
Temporarily impaired securities, fair value, 12 months or longer	302,535	326,252
Temporarily impaired securities, unrealized losses, 12 months or longer	(44,224)	(43,013)
Commercial Mortgage-Backed Securities [Member]
Temporarily impaired securities, fair value	26,628	26,969
Temporarily impaired securities, unrealized losses	(3,335)	(3,155)
Temporarily impaired securities, fair value, less than 12 months	5,267	5,421
Temporarily impaired securities, unrealized losses, less than 12 months	(188)	(96)
Temporarily impaired securities, fair value, 12 months or longer	21,361	21,548
Temporarily impaired securities, unrealized losses, 12 months or longer	(3,147)	(3,059)
US States and Political Subdivisions Debt Securities [Member]
Temporarily impaired securities, fair value	100,319	103,918
Temporarily impaired securities, unrealized losses	(17,396)	(14,521)
Temporarily impaired securities, fair value, less than 12 months	15,319	4,276
Temporarily impaired securities, unrealized losses, less than 12 months	(406)	(20)
Temporarily impaired securities, fair value, 12 months or longer	85,000	99,642
Temporarily impaired securities, unrealized losses, 12 months or longer	(16,990)	(14,501)
Corporate Debt Securities [Member]
Temporarily impaired securities, fair value	6,958	1,997
Temporarily impaired securities, unrealized losses	(42)	(3)
Temporarily impaired securities, fair value, less than 12 months	6,958	1,997
Temporarily impaired securities, unrealized losses, less than 12 months	(42)	(3)
Temporarily impaired securities, fair value, 12 months or longer	0	0
Temporarily impaired securities, unrealized losses, 12 months or longer	0	0
Asset-Backed Securities [Member]
Temporarily impaired securities, fair value	270	525
Temporarily impaired securities, unrealized losses	(3)	(3)
Temporarily impaired securities, fair value, less than 12 months	0	242
Temporarily impaired securities, unrealized losses, less than 12 months	0	0
Temporarily impaired securities, fair value, 12 months or longer	270	283
Temporarily impaired securities, unrealized losses, 12 months or longer	$ (3)	$ (3)

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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