Note 4 - Investment Securities - Portfolio of Securities Available-for-sale (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Amortized cost	$ 1,264,090	$ 1,308,082
Gross unrealized gains	8,677	13,265
Gross unrealized losses	(76,383)	(70,409)
Securities available-for-sale, fair value	1,196,384	1,250,938
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
US Government Agencies Debt Securities [Member]
Amortized cost	362,898	398,392
Gross unrealized gains	2,088	2,467
Gross unrealized losses	(10,183)	(9,669)
Securities available-for-sale, fair value	354,803	391,190
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
Residential Mortgage-Backed Securities [Member]
Amortized cost	637,699	644,811
Gross unrealized gains	3,883	5,391
Gross unrealized losses	(45,424)	(43,058)
Securities available-for-sale, fair value	596,158	607,144
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
Commercial Mortgage-Backed Securities [Member]
Amortized cost	29,963	30,124
Gross unrealized gains	0	0
Gross unrealized losses	(3,335)	(3,155)
Securities available-for-sale, fair value	26,628	26,969
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
US States and Political Subdivisions Debt Securities [Member]
Amortized cost	219,262	221,545
Gross unrealized gains	2,697	5,385
Gross unrealized losses	(17,396)	(14,521)
Securities available-for-sale, fair value	204,563	212,409
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
Corporate Debt Securities [Member]
Amortized cost	13,500	12,500
Gross unrealized gains	8	22
Gross unrealized losses	(42)	(3)
Securities available-for-sale, fair value	13,466	12,519
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
Asset-Backed Securities [Member]
Amortized cost	508	528
Gross unrealized gains	1	0
Gross unrealized losses	(3)	(3)
Securities available-for-sale, fair value	506	525
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Excluding Accrued Interest	0	0
Other Debt Obligations [Member]
Amortized cost	260	182
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Securities available-for-sale, fair value	260	182
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/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477657/942-210-S45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478478/942-210-S50-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
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-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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