Note 4 - Investment Securities - Securities in an Unrealized Loss Position (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Temporarily impaired securities, fair value	$ 574,628	$ 554,720
Temporarily impaired securities, unrealized losses	(87,499)	(96,074)
Temporarily impaired securities, fair value, less than 12 months	94,018	60,543
Temporarily impaired securities, unrealized losses, less than 12 months	(1,563)	(1,004)
Temporarily impaired securities, fair value, 12 months or longer	480,610	494,177
Temporarily impaired securities, unrealized losses, 12 months or longer	(85,936)	(95,070)
US Government Agencies Debt Securities [Member]
Temporarily impaired securities, fair value	84,641	53,467
Temporarily impaired securities, unrealized losses	(10,649)	(11,674)
Temporarily impaired securities, fair value, less than 12 months	50,658	18,471
Temporarily impaired securities, unrealized losses, less than 12 months	(255)	(60)
Temporarily impaired securities, fair value, 12 months or longer	33,983	34,996
Temporarily impaired securities, unrealized losses, 12 months or longer	(10,394)	(11,614)
Residential Mortgage-Backed Securities [Member]
Temporarily impaired securities, fair value	350,770	364,971
Temporarily impaired securities, unrealized losses	(52,352)	(60,818)
Temporarily impaired securities, fair value, less than 12 months	21,050	26,809
Temporarily impaired securities, unrealized losses, less than 12 months	(377)	(604)
Temporarily impaired securities, fair value, 12 months or longer	329,720	338,162
Temporarily impaired securities, unrealized losses, 12 months or longer	(51,975)	(60,214)
Commercial Mortgage-Backed Securities [Member]
Temporarily impaired securities, fair value	21,131	20,892
Temporarily impaired securities, unrealized losses	(3,730)	(4,097)
Temporarily impaired securities, fair value, less than 12 months	0	0
Temporarily impaired securities, unrealized losses, less than 12 months	0	0
Temporarily impaired securities, fair value, 12 months or longer	21,131	20,892
Temporarily impaired securities, unrealized losses, 12 months or longer	(3,730)	(4,097)
US States and Political Subdivisions Debt Securities [Member]
Temporarily impaired securities, fair value	115,530	112,523
Temporarily impaired securities, unrealized losses	(20,752)	(19,460)
Temporarily impaired securities, fair value, less than 12 months	20,316	13,281
Temporarily impaired securities, unrealized losses, less than 12 months	(925)	(322)
Temporarily impaired securities, fair value, 12 months or longer	95,214	99,242
Temporarily impaired securities, unrealized losses, 12 months or longer	(19,827)	(19,138)
Corporate Debt Securities [Member]
Temporarily impaired securities, fair value	1,994	1,982
Temporarily impaired securities, unrealized losses	(6)	(18)
Temporarily impaired securities, fair value, less than 12 months	1,994	1,982
Temporarily impaired securities, unrealized losses, less than 12 months	(6)	(18)
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	562	885
Temporarily impaired securities, unrealized losses	(10)	(7)
Temporarily impaired securities, fair value, less than 12 months	0	0
Temporarily impaired securities, unrealized losses, less than 12 months	0	0
Temporarily impaired securities, fair value, 12 months or longer	562	885
Temporarily impaired securities, unrealized losses, 12 months or longer	$ (10)	$ (7)

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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