Income Taxes (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
Sep. 30, 2025 |
|
| Income Tax Disclosure [Abstract] | |||||
| Effective income tax rate | 13.20% | 14.30% | 15.30% | 15.80% | |
| Gross unrecognized tax benefits | $ 21 | $ 21 | $ 29 | ||
| Accrued interest and penalties related to unrecognized tax benefits | 2 | 2 | $ 2 | ||
| Reasonably possible amount of reduction in gross unrecognized tax benefits for the next twelve months | 14 | 14 | |||
| Reasonably possible amount of net reduction to income tax provision if unrecognized tax benefits were recognized | $ 14 | $ 14 | |||