Note 4 - Investment Securities - Portfolio of Securities Available-for-sale (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Amortized cost	$ 1,309,724		$ 708,437
Gross unrealized gains	4,975		484
Gross unrealized losses	(87,499)		(96,074)
Obligations of U.S. states and political subdivisions	1,227,200		612,847
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	$ 0	0
US Government Agencies Debt Securities [Member]
Amortized cost	368,785		96,165
Gross unrealized gains	1,281		179
Gross unrealized losses	(10,649)		(11,674)
Obligations of U.S. states and political subdivisions	359,417		84,670
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0		0
Residential Mortgage-Backed Securities [Member]
Amortized cost	677,879		439,445
Gross unrealized gains	2,612		211
Gross unrealized losses	(52,352)		(60,818)
Obligations of U.S. states and political subdivisions	628,139		378,838
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0		0
Commercial Mortgage-Backed Securities [Member]
Amortized cost	30,266		24,989
Gross unrealized gains	36		0
Gross unrealized losses	(3,730)		(4,097)
Obligations of U.S. states and political subdivisions	26,572		20,892
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0		0
US States and Political Subdivisions Debt Securities [Member]
Amortized cost	226,834		141,775
Gross unrealized gains	1,044		89
Gross unrealized losses	(20,752)		(19,460)
Obligations of U.S. states and political subdivisions	207,126		122,404
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0		0
Corporate Debt Securities [Member]
Amortized cost	5,000		5,000
Gross unrealized gains	1		5
Gross unrealized losses	(6)		(18)
Obligations of U.S. states and political subdivisions	4,995		4,987
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0		0
Asset-Backed Securities [Member]
Amortized cost	832		892
Gross unrealized gains	1		0
Gross unrealized losses	(10)		(7)
Obligations of U.S. states and political subdivisions	823		885
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0		0
Other Debt Obligations [Member]
Amortized cost	128		171
Gross unrealized gains	0		0
Gross unrealized losses	0		0
Obligations of U.S. states and political subdivisions	128		171
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	$ 0		$ 0

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 30
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-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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