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Income Taxes - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands | 12 Months Ended |
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2022
Operating Loss Carryforwards [Line Items] |  |  |  |
Income Tax Holiday, Aggregate Dollar Amount | $ 9,400 | $ 7,200 | $ 6,000 |
Income Tax Holiday, Income Tax Benefits Per Share | $ 0.16 | $ 0.12 | $ 0.10 |
Deferred Tax Assets, Operating Loss Carryforwards | $ 47,028 | $ 34,787 |  |
Deferred Tax Assets, Tax Credit Carryforwards | 27,398 | 25,052 |  |
Valuation Allowance, Deferred Tax Asset, Change in Amount | (5,400) | (4,300) |  |
Unrecognized Tax Benefits | 86,597 | 86,877 | $ 79,167 | $ 66,840
Unrecognized Tax Benefits that Would Impact Effective Tax Rate | 54,700 | 56,200 | 51,200 |
Unrecognized Tax Benefits, Period Increase (Decrease) | 900 | 5,600 | $ 3,300 |
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued | 12,700 | $ 11,800 |  |
Foreign [Member] |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration | 53,200 |  |  |
Deferred Tax Assets, Tax Credit Carryforwards, Subject to Expiration | 2,500 |  |  |
Domestic Tax Jurisdiction [Member] |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration | 107,700 |  |  |
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration | 15,200 |  |  |
Deferred Tax Assets, Operating Loss Carryforwards | 122,900 |  |  |
Deferred Tax Assets, Tax Credit Carryforwards, Subject to Expiration | 4,100 |  |  |
State and Local Jurisdiction [Member] |  |  |  |
Operating Loss Carryforwards [Line Items] |  |  |  |
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration | 92,000 |  |  |
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration | 168,800 |  |  |
Deferred Tax Assets, Operating Loss Carryforwards | 260,800 |  |  |
Deferred Tax Assets, Tax Credit Carryforwards | 37,600 |  |  |
Deferred Tax Assets, Tax Credit Carryforwards, Subject to Expiration | $ 3,200 |  |  |

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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482685/740-10-50-6 + Details
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards that are not subject to expiration dates. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482685/740-10-50-6 + Details
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- Definition The amount of income taxes from which a reporting entity is exempt or for which it will receive a reduction in income taxes as a result of the income tax holiday granted by the taxing jurisdiction. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 740 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 11.C) -Publisher FASB -URI https://asc.fasb.org/1943274/2147479360/740-10-S99-2 + Details
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