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Note 3 - Stock-based Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Millions |  | 1 Months Ended | 9 Months Ended |
--- | --- | --- | --- | ---
Jun. 11, 2020 | Feb. 28, 2025 | Sep. 30, 2025 | Sep. 30, 2024 | Nov. 13, 2014
Share Price (in dollars per share) |  | $ 656.29 | $ 920.64 |  |
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount |  |  | $ 260.7 |  |
Restricted Stock Units (RSUs) [Member] |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested |  |  | 49.6 | $ 494.4 |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding |  |  | $ 1,700.0 |  |
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) |  |  | 2 years |  |
Time-Based RSUs [Member] |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  |  | 38,000 |  |
Time-Based RSUs [Member] | Employees [Member] |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  |  | 38,000 |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year) |  |  | 4 years |  |
Time-Based RSUs [Member] | Director [Member] |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year) |  |  | 1 year |  |
PSU 2025 [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Price Per Share Payable Upon Vesting of Equity Instruments Other than Options (in dollars per share) |  | $ 30 |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term (Year) |  | 3 years |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate |  | 54.42% |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate |  | 4.20% |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate |  | 0.95% |  |  |
PSU 2025 [Member] | Minimum [Member] |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Correlation Coefficient |  | 0.46 |  |  |
PSU 2025 [Member] | Maximum [Member] |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Correlation Coefficient |  | 0.76 |  |  |
PSU 2025 [Member] | Executive Officer [Member] |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  | 50,000 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed, First Goal |  | 300.00% |  |  |
Maximum Stock Compensation Costs |  | $ 138.5 |  |  |
PSU 2025 [Member] | Executive Officer [Member] | Share-Based Payment Arrangement, Tranche Two [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed, Second Goal |  | 200.00% |  |  |
PSU 2025 [Member] | Non-Executive Employees [Member] |  |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares) |  | 11,000 |  |  |
Maximum Stock Compensation Costs |  | $ 16.5 |  |  |
PSU 2025 [Member] | Non-Executive Employees [Member] | Minimum [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Minimum Percentage Allowed |  | 200.00% |  |  |
PSU 2025 [Member] | Non-Executive Employees [Member] | Maximum [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed |  | 300.00% |  |  |
PSU 2025 [Member] | Non-Executive Employees [Member] | Vesting First Quarter of 2027 [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage |  | 50.00% |  |  |
The2014 Plan [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares) |  |  |  |  | 5,500,000
Amended and Restated 2014 Plan [Member] |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in shares) | 10,500,000 |  |  |  |
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares) |  |  | 3,600,000 |  |

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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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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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- Definition Number of additional shares authorized for issuance under share-based payment arrangement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-4 + Details
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- Definition Number of shares authorized for issuance under share-based payment arrangement. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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