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Note 5 - Mortgage Servicing Rights (Details Textual) - Mortgage Servicing Rights [Member] - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Fair Value Disclosure, off-Balance-Sheet Risks, Face Amount, Asset | $ 2,832,016 | $ 2,783,458 |
Servicing Asset at Fair Value, Amount | 38,200 | 35,500 |
Contractually Specified Servicing Fee, Late Fee, and Ancillary Fee Earned in Exchange for Servicing Financial Asset | $ 7,200 | $ 7,100 | $ 6,300
Minimum [Member] |  |  |
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of Other than 10 or 20 Percent Adverse Change in Other Assumption, Percent | 0.50% |  |
Maximum [Member] |  |  |
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of Other than 10 or 20 Percent Adverse Change in Other Assumption, Percent | 1.00% |  |

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- Definition Amount of contractually specified servicing fee, late fee, and ancillary fee recognized as income for servicing asset and servicing liability. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481229/860-50-50-2 + Details
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- Definition The face amount of financial assets, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition. + References No definition available. + Details
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- Definition A specified percentage variance in a specified key assumption in the determination of fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 860 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481326/860-20-50-4 + Details
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- Definition Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481229/860-50-50-3 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481260/860-50-45-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481260/860-50-45-1 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 860 -SubTopic 50 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481260/860-50-45-2 + Details
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- Details
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