Legal Matters - Schedule of Accrued Litigation for Both Covered and Non-Covered Litigation (Details) - USD ($) $ in Millions |
9 Months Ended | |
|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
|
| Loss Contingency Accrual [Roll Forward] | ||
| Balance at beginning of period | $ 1,727 | $ 1,751 |
| Balance at end of period | 2,352 | 1,688 |
| Uncovered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Provision for legal matters | 114 | 311 |
| Covered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Provision for legal matters | 1,564 | 201 |
| Payments for legal matters | (1,053) | (575) |
| U.S. Covered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Balance at beginning of period | 1,537 | 1,621 |
| Provision for legal matters | 1,545 | 140 |
| Payments for legal matters | (827) | (204) |
| Balance at end of period | 2,255 | 1,557 |
| VE Territory Covered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Balance at beginning of period | 72 | 110 |
| Provision for legal matters | 19 | 61 |
| Payments for legal matters | (85) | (146) |
| Balance at end of period | $ 6 | $ 25 |