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Note 4 - Loans and Allowance for Credit Losses (Details Textual) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024 | Mar. 31, 2025 | Dec. 31, 2024 | Dec. 21, 2024 | Mar. 31, 2024 | Dec. 31, 2023
Financing Receivable, Unamortized Loan Cost (Fee) | $ 300 |  | $ 300 |  |  | $ 1,100 |  |  |
Interest Receivable | 20,884 |  | 20,884 |  |  | 20,075 |  |  |
Proceeds from Sale of Notes Receivable |  |  | 12,331 | $ 0 |  |  |  |  |
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss | 4,044,657 |  | 4,044,657 |  |  | 3,992,534 |  |  |
Off-Balance-Sheet, Credit Loss, Liability, Credit Loss Expense (Reversal) | 1,200 | $ 275,000 | 2,700 | 500 |  |  |  |  |
Debt Securities, Held-to-Maturity, Credit Loss Expense (Reversal) | 2 | 56 | 4 | 62 |  |  |  |  |
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest | 59,278 | 38,332 | 59,278 | 38,332 | $ 61,929 | 59,929 |  | $ 36,584 | $ 35,843
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Period Increase (Decrease) |  |  | $ 600 |  |  |  |  |  |
Percentage of Increase in Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest |  |  | 1.10% |  |  |  |  |  |
Loans and Leases Receivables, Impaired, Troubled Debt, Interest Income | 1,100 | 200 |  |  |  |  |  |  |
Financing Receivable, Nonaccrual, Interest Income | 0 | 0 |  |  |  |  |  |  |
Financing Receivable, Excluding Accrued Interest, Modified in Period, Amount | 0 | 0 |  | 0 |  |  |  |  |
Financing Receivable, Excluding Accrued Interest, Modified, Subsequent Default |  | $ 0 | $ 0 | $ 0 |  |  |  |  |
Asset Pledged as Collateral [Member] | FHLB Borrowings, Deposits, and Other [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss | 2,900,000 |  | 2,900,000 |  |  | 2,900,000 |  |  |
Loans Receivable [Member] |  |  |  |  |  |  |  |  |
Interest Receivable | 17,500 |  | 17,500 |  |  | 16,400 |  |  |
Non-mortgage Loans [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Held-for-Sale, Not Part of Disposal Group, after Valuation Allowance | 50,160 |  | 50,160 |  |  | $ 0 |  |  |
Financing Receivable, Transfer to Held-for-Sale, Valuation Allowance, Expense | 78 |  |  |  |  |  |  |  |
Proceeds from Sale of Notes Receivable | 12,300 |  |  |  |  |  |  |  |
Financing Receivable, Excluding Accrued Interest, Transfer out, Allowance for Credit Loss, Expense Reversal | 78 |  | 78 |  |  |  |  |  |
Metro Phoenix Bank and HMN Financial Inc. [Member] |  |  |  |  |  |  |  |  |
Financing Receivable, Unamortized Purchase Premium (Discount) | $ 52,700 |  | $ 52,700 |  |  |  | $ 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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