Note 4 - Investment Securities - Investment Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Investment securities available for sale, amortized cost	$ 1,657,883	$ 1,735,451
Investment securities available for sale, gross unrealized gains	99	1,142
Investment securities available for sale, gross unrealized losses	68,946	78,370
Securities AFS	1,589,036	1,658,223
US Treasury Securities [Member]
Investment securities available for sale, amortized cost	925,220	827,763
Investment securities available for sale, gross unrealized gains	0	430
Investment securities available for sale, gross unrealized losses	573	0
Securities AFS	924,647	828,193
US Government Corporations and Agencies Securities [Member]
Investment securities available for sale, amortized cost	611	5,888
Investment securities available for sale, gross unrealized gains	51	52
Investment securities available for sale, gross unrealized losses	84	118
Securities AFS	578	5,822
Collateralized Mortgage-Backed Securities [Member]
Investment securities available for sale, amortized cost	701,414	704,213
Investment securities available for sale, gross unrealized gains	43	548
Investment securities available for sale, gross unrealized losses	66,840	75,324
Securities AFS	634,617	629,437
US Government-sponsored Enterprises Debt Securities [Member]
Investment securities available for sale, amortized cost		25,000
Investment securities available for sale, gross unrealized gains		11
Investment securities available for sale, gross unrealized losses		0
Securities AFS		25,011
Collateralized Mortgage Obligations [Member]
Investment securities available for sale, amortized cost	5,638	24,454
Investment securities available for sale, gross unrealized gains	0	0
Investment securities available for sale, gross unrealized losses	1,429	1,706
Securities AFS	4,209	22,748
Corporate Debt Securities [Member]
Investment securities available for sale, amortized cost	25,000	148,133
Investment securities available for sale, gross unrealized gains	5	101
Investment securities available for sale, gross unrealized losses	20	1,222
Securities AFS	$ 24,985	$ 147,012

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
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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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Amount excluding accrued interest, of 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 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
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-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
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-SubTopic 30
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-Section 45
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-Publisher FASB
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