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Other Financial Information - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Nov. 18, 2025 | Sep. 30, 2025 | Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2023
Other Financials Information [Line Items] |  |  |  |  |
Accrued contract costs including professional liability accruals |  | $ 1,419,000 | $ 1,419,000 | $ 1,354,700 |
Restructuring expenses incurred |  |  | 59,355 | 98,918 | $ 188,404
Accrued restructuring expenses |  | $ 15,000 | 15,000 | 11,900 |
Cash dividends declared (in dollars per share) |  | $ 0.26 |  |  |
Accrued and unpaid dividend |  | $ 37,600 | 37,600 |  |
Subsequent Event |  |  |  |  |
Other Financials Information [Line Items] |  |  |  |  |
Cash dividends declared (in dollars per share) | $ 0.31 |  |  |  |
Labor-Related Costs |  |  |  |  |
Other Financials Information [Line Items] |  |  |  |  |
Restructuring expenses incurred |  |  | 32,000 | 18,700 |
Non-Labor Costs |  |  |  |  |
Other Financials Information [Line Items] |  |  |  |  |
Restructuring expenses incurred |  |  | 27,300 | 80,200 |
Professional Liability Accrual |  |  |  |  |
Other Financials Information [Line Items] |  |  |  |  |
Accrued contract costs including professional liability accruals |  | $ 893,700 | $ 893,700 | $ 831,800 |

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- Definition Carrying value as of the balance sheet date of obligations incurred through that date and payable for obligations related to professional liability and costs for services provided by subcontractors and other non-employees. It is used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle, whichever is longer). + References No definition available. + Details
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