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Note 11 - Stock-based Compensation (Details Textual) - USD ($) $ in Millions |  |  |  |  |  |  | 9 Months Ended | 12 Months Ended | 24 Months Ended | 36 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Nov. 25, 2022 | Jun. 09, 2022 | May 26, 2022 | May 27, 2021 | Jun. 01, 2020 | May 23, 2019 | May 31, 2021 | May 31, 2023 | Dec. 31, 2022 | May 31, 2022 | Dec. 31, 2021 | May 31, 2021 | Dec. 31, 2020 | May 31, 2020 | Aug. 27, 2022 | Dec. 31, 2016
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized (in shares) |  |  |  |  |  |  |  |  | 66,000 |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares) |  |  |  |  |  |  |  |  | 0 |  | 0 |  | 0 |  |  |
Stock Issued During Period, Shares, Issued for Services (in shares) |  |  |  |  |  |  |  |  | 11,166 |  | 10,489 |  | 17,716 |  |  |
Noninterest Expense [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Payment Arrangement, Expense |  |  |  |  |  |  |  |  | $ 3.4 |  | $ 3.8 |  | $ 2.3 |  |  |
Director [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, Issued for Services (in shares) |  |  | 10,300 | 10,500 | 16,000 | 12,000 |  |  |  |  |  |  |  |  |  |
Share-based Payment Arrangement, Expense |  |  |  |  |  |  |  |  |  | $ 0.3 |  | $ 0.3 |  | $ 0.4 |  |
Director [Member] | Forecast [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Payment Arrangement, Expense |  |  |  |  |  |  |  | $ 0.3 |  |  |  |  |  |  |  |
Corporate and Bank Board Members [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, Issued for Services (in shares) |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,700 |
Bank Board Members [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock Issued During Period, Shares, Issued for Services (in shares) | 300 | 600 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Payment Arrangement, Expense |  |  |  |  |  |  | $ 0.1 |  |  |  |  |  |  |  |  |
Bank Board Members [Member] | Forecast [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Payment Arrangement, Expense |  |  |  |  |  |  |  | $ 0.1 |  |  |  |  |  |  |  |
Restricted Stock [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |
Share-Based Payment Arrangement, Option [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 years
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 110.00%
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7 years
Performance Shares [Member] | Executive Officer [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  |  |  |  |  |  |  |  | 26,112 |  | 22,703 |  | 31,295 |  |  |
Performance Shares [Member] | Executive Officer [Member] | The 2021 Award [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  |  |  |  |  |  |  |  | 11,350 |  |  |  |  |  |  |
Performance Shares [Member] | Executive Officer [Member] | The 2020 Awards [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  |  |  |  |  |  |  |  | 2,778 |  | 11,454 |  |  |  |  |
Performance Shares [Member] | Executive Officer [Member] | The 2019 Awards [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  |  |  |  |  |  |  |  | 690 |  | 23,053 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period (in shares) |  |  |  |  |  |  |  |  |  |  |  |  | 13,709 |  |  |
Performance Shares [Member] | Executive Officer [Member] | The 2018 Awards [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  |  |  |  |  |  |  |  |  |  | 22,836 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period (in shares) |  |  |  |  |  |  |  |  |  |  |  |  | 14,681 |  |  |

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- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901 + Details
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- Definition Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(01) -URI https://asc.fasb.org/extlink&oid=128089324&loc=d3e5070-113901 + Details
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