Note 4 - Investment Securities - Portfolio of Securities Available-for-sale (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Amortized cost	$ 1,316,828	$ 708,437
Gross unrealized gains	10,671	484
Gross unrealized losses	(75,297)	(96,074)
Obligations of U.S. states and political subdivisions	1,252,202	612,847
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
US Government Agencies Debt Securities [Member]
Amortized cost	406,606	96,165
Gross unrealized gains	2,636	179
Gross unrealized losses	(10,114)	(11,674)
Obligations of U.S. states and political subdivisions	399,128	84,670
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
Residential Mortgage-Backed Securities [Member]
Amortized cost	649,730	439,445
Gross unrealized gains	4,026	211
Gross unrealized losses	(45,857)	(60,818)
Obligations of U.S. states and political subdivisions	607,899	378,838
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
Commercial Mortgage-Backed Securities [Member]
Amortized cost	30,180	24,989
Gross unrealized gains	0	0
Gross unrealized losses	(3,373)	(4,097)
Obligations of U.S. states and political subdivisions	26,807	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	223,707	141,775
Gross unrealized gains	4,008	89
Gross unrealized losses	(15,950)	(19,460)
Obligations of U.S. states and political subdivisions	211,765	122,404
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
Corporate Debt Securities [Member]
Amortized cost	6,000	5,000
Gross unrealized gains	0	5
Gross unrealized losses	(1)	(18)
Obligations of U.S. states and political subdivisions	5,999	4,987
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
Asset-Backed Securities [Member]
Amortized cost	551	892
Gross unrealized gains	1	0
Gross unrealized losses	(2)	(7)
Obligations of U.S. states and political subdivisions	550	885
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
Other Debt Obligations [Member]
Amortized cost	54	171
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Obligations of U.S. states and political subdivisions	54	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
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-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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