Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2024 |
|
| Allowance for credit losses | |||
| Valuation and Qualifying Accounts | |||
| Balance at Beginning of Year | $ 21 | $ 22 | $ 17 |
| Charged to Costs and Expenses | 1 | 5 | 13 |
| Charged to Other Accounts | 0 | 0 | 0 |
| Deductions | 7 | 6 | 8 |
| Balance at End of Year | 15 | 21 | 22 |
| Valuation allowance for deferred tax assets | |||
| Valuation and Qualifying Accounts | |||
| Balance at Beginning of Year | 129 | 98 | 89 |
| Charged to Costs and Expenses | 4 | 44 | 11 |
| Charged to Other Accounts | 0 | 0 | 2 |
| Deductions | 112 | 13 | 4 |
| Balance at End of Year | $ 21 | $ 129 | $ 98 |