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Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024 | Sep. 30, 2024 | Sep. 30, 2023
Income Taxes [Line Items] |  |  |  |  |  |
Interest expense carryovers |  |  |  |  | $ 9,258 | $ 6,457
Operating loss carryforwards, valuation allowance |  |  |  |  | 41,600 | 21,100
Unrecognized tax benefits if unrecognized, the balance of uncertain tax benefits would impact the effective tax rate |  |  |  |  | 4,900 | $ 4,900
Effective tax rate (ETR) from continuing operations | (1.20%) | 3.90% | 3.70% | (0.20%) |  |
Domestic Tax Authority [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
Net operating loss carryforwards not subject to expiration |  |  |  |  | $ 194,200 |
Effective income tax rate reconciliation, at federal statutory income tax rate, percent |  |  |  |  | 80.00% |
Interest expense carryovers |  |  |  |  | $ 41,700 |
Domestic Tax Authority [Member] | 2030-2038 [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
Net operating loss carryforwards | $ 277,600 |  | $ 277,600 |  | 511,700 |
State and Local Jurisdiction [Member] | 2024-2043 [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
Net operating loss carryforwards | $ 150,600 |  | $ 150,600 |  | $ 226,900 |
Minimum [Member] | Domestic Tax Authority [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
Operating loss carryforwards, expiration year |  |  | 2030 |  | 2027 |
Minimum [Member] | State and Local Jurisdiction [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
Operating loss carryforwards, expiration year |  |  | 2024 |  | 2024 |
Maximum [Member] | Domestic Tax Authority [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
Operating loss carryforwards, expiration year |  |  | -2038 |  | 2038 |
Maximum [Member] | State and Local Jurisdiction [Member] |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |
Operating loss carryforwards, expiration year |  |  | -2043 |  | 2044 |

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- Definition Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible interest carryforward. + 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 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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