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Commitments and Contingencies - Legal Proceedings (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2024 | Sep. 30, 2023
Legal Proceedings |  |
Contribution related to TVARS case | $ 5 | $ 4
Amount remaining to be spent under environmental agreements | 7 |
General |  |
Legal Proceedings |  |
Legal loss contingency accrual | 10 |
Environmental Agreements |  |
Legal Proceedings |  |
Amount to be invested in certain environmental projects | 290 |
Amount invested in certain environmental projects | 284 |
Other long-term liabilities | General |  |
Legal Proceedings |  |
Legal loss contingency accrual | 9 |
Accounts payable and accrued liabilities | General |  |
Legal Proceedings |  |
Legal loss contingency accrual | $ 1 |

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