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Note 8 - Stock-based Incentive Plans (Details Textual) - USD ($) |  |  |  |  | 3 Months Ended | 6 Months Ended
--- | --- | --- | --- | --- | --- | ---
Feb. 07, 2023 | Feb. 06, 2023 | May 14, 2021 | Mar. 15, 2021 | Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022
Restricted Stock [Member] |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  | 97,900 |  |  |  |  | 97,900 |
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year) |  | 3 years |  |  |  |  |  |
Share-Based Payment Arrangement, Expense |  |  |  |  | $ 39,000 |  | $ 85,000 |
Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount |  |  |  |  | $ 388,000 |  | $ 388,000 |
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) |  |  |  |  |  |  | 1 year 4 months 24 days |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares) |  |  |  |  |  |  | 16,324 |
Equity Incentive Plan 2016 [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares) |  |  |  |  | 2,500,000 |  | 2,500,000 |
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares) |  |  |  |  | 1,121,683 |  | 1,121,683 |
The Phantom Plan [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year) |  |  |  | 10 years |  |  |  |
The Phantom Plan [Member] | Phantom Shares [Member] | Employees and Non-Employee Directors [Member] |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | 212,937 |  |  | 223,307 |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year) |  |  |  | 3 years |  |  |  |
Share-Based Payment Arrangement, Expense |  |  |  |  | $ 133,000 | $ 153,000 | $ 260,000 | $ 349,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Payment Per Share (in dollars per share) | $ 12.00 |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares) |  |  |  |  | 26,617 | 27,913 | 53,234 | 55,826
The Phantom Plan [Member] | Phantom Shares [Member] | Employees and Non-Employee Directors [Member] | Vesting Increments [Member] |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year) | 3 years |  |  |  |  |  |  |
The Phantom Plan [Member] | Phantom Shares [Member] | Employees and Non-Employee Directors [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Payment Per Share (in dollars per share) |  |  |  | $ 12.00 |  |  |  |
The Phantom Plan [Member] | Phantom Shares [Member] | NewNonEmployeeDirectorsMember |  |  |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  |  | 9,074 |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares) |  |  | 9,074 |  |  |  |  |

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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 -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479830/718-10-S99-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + 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 -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + 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 -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(01) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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