Note 3 - Loans and Allowance for Credit Losses on Loans (Details Textual) Pure in Thousands	3 Months Ended	6 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Jun. 30, 2025 USD ($)	Jun. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)
Financing Receivable, Accrued Interest, after Allowance for Credit Loss			$ 23,000,000		$ 23,000,000
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss			6,850,273,000		6,520,402,000
Loans and Leases Receivable, Related Parties			91,000,000		97,000,000
Financing Receivable, Nonaccrual, Interest Income			0	$ 0
Mortgage Loans in Process of Foreclosure, Amount			717,000		569,000
Financing Receivable, Modifications, Number of Contracts	0	0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default, Number of Contracts	0	0
Asset Pledged as Collateral [Member] \| Federal Home Loan Bank Advances [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss			$ 3,650,000,000		$ 3,480,000,000

Number of financing receivables that have been modified by troubled debt restructurings.

No definition available.

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- Definition

Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

No definition available.

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- Definition

Amount, after allowance for credit loss, of accrued interest on financing receivable.

+ References

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-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
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- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
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-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

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- Definition

Amount of interest income on financing receivable on nonaccrual status.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
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- Definition

For an unclassified balance sheet, reflects the carrying amount of unpaid loan amounts due from related parties at the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
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- Definition

Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 35
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-35

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