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Note 4 - Loans and Allowance for Credit Losses (Details Textual) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Mar. 31, 2025 | Mar. 31, 2024 | Dec. 31, 2024 | Dec. 21, 2024 | Dec. 31, 2023
Financing Receivable, Unamortized Loan Cost (Fee) | $ 1,000 |  | $ 1,100 |  |
Interest Receivable | 20,505 |  | 20,075 |  |
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss | 4,085,483 |  | 3,992,534 |  |
Off-Balance-Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal) | 1,500 | $ 793,000 |  |  |
Debt Securities, Held-to-Maturity, Credit Loss Expense (Reversal) | 2 | 6 |  |  |
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest | 61,929 | 36,584 | 59,929 |  | $ 35,843
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Period Increase (Decrease) | $ 2,000 |  |  |  |
Percentage of Increase in Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest | 3.30% |  |  |  |
Loans and Leases Receivables, Impaired, Troubled Debt, Interest Income | $ 1,100 | 700 |  |  |
Financing Receivable, Nonaccrual, Interest Income | 0 |  | 0 |  |
Commercial Borrower [Member] |  |  |  |  |
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss | 2,881,103 |  | 2,787,277 |  |
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest | 52,448 | $ 28,610 | 50,130 |  | $ 27,971
Commercial Borrower [Member] | Commercial Portfolio Segment [Member] |  |  |  |  |
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Period Increase (Decrease) | 2,100 |  |  |  |
Asset Pledged as Collateral [Member] | FHLB Borrowings, Deposits, and Other [Member] |  |  |  |  |
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss | 2,900 |  | 2,900 |  |
Loans Receivable [Member] |  |  |  |  |
Interest Receivable | 17,000 |  | $ 16,400 |  |
Metro Phoenix Bank and HMN Financial Inc. [Member] |  |  |  |  |
Financing Receivable, Unamortized Purchase Premium (Discount) | $ 65,100 |  |  | $ 70,600 |

X
- Definition The gross interest income that would have been recorded in the period on troubled debt restructurings, if the loans had been current in accordance with their original terms and had been outstanding throughout the period or since origination, if held for part of the period. + References No definition available. + Details
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- Definition Amount of expense (reversal of expense) for expected credit loss on investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 13 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 220 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 22 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147476148/220-40-50-22 + Details
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- Definition Amount excluding accrued interest, of allowance for credit loss on 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 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479344/326-20-45-1 + Details
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- Definition Amount, excluding accrued interest, of increase (decrease) in allowance for credit loss on 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 50 -Paragraph 13 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-13 + Details
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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 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479344/326-20-45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 3B -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-3B Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479319/326-20-50-5 + Details
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- Definition Amount of unamortized loan commitment, origination, and other costs (fees) on financing receivable recognized as adjustment to yield. Excludes financing receivable covered under loss sharing agreement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 310 -SubTopic 20 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481598/310-20-45-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-4 Reference 3: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 3 -SubTopic 20 -Topic 310 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481569/310-20-50-3 + Details
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