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Note 6 - Share-based Compensation (Details Textual) $ / shares in Units, $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2024 USD ($) $ / shares shares | Sep. 30, 2023 $ / shares shares | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Number Of Active Stock Incentive Plans |  | 1 |  |  |  |
Number Of Inactive Stock Incentive Plans |  | 1 |  |  |  |
Performance Shares [Member] |  |  |  |  |  |
Performance Share Award Target Level, Percentage |  | 100.00% |  |  |  |
Performance Awards Issued Multiplier |  |  |  | 90.00% | 110.00% | 123.00%
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number At Target Level Of Performance (in shares) |  | 180,000 |  |  |  |
Performance Shares [Member] | Minimum [Member] |  |  |  |  |  |
Performance Awards Issued Multiplier |  | 0.00% |  |  |  |
Performance Shares [Member] | Maximum [Member] |  |  |  |  |  |
Performance Awards Issued Multiplier |  | 200.00% |  |  |  |
Restricted Stock Units and Performance Stock Awards [Member] |  |  |  |  |  |
Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount | $ |  | $ 4.9 |  |  |  |
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) |  | 1 year 7 months 6 days |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) | [1] | 120,143 |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares |  | $ 34.68 |  |  |  |
Stock Awards [Member] | Director [Member] |  |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  | 14,424 | 15,904 |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares |  | $ 33.27 | $ 29.51 |  |  |
[1] | The number of PSAs disclosed in this table are at the target level of 100%.

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- Definition Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (i) -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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