Legal Matters - Legal Matters - Schedule of Accrued Litigation for Both Covered and Non-Covered Litigation (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Sep. 30, 2022 |
Sep. 30, 2021 |
|
| Loss Contingency Accrual [Roll Forward] | ||
| Balance at beginning of period | $ 983 | $ 914 |
| Balance at end of period | 1,456 | 983 |
| Uncovered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Provision for legal matters | 6 | 4 |
| Covered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Provision for legal matters | 885 | 125 |
| Payments on legal matters | (418) | (60) |
| U.S. Covered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Balance at beginning of period | 881 | 888 |
| Provision for legal matters | 861 | |
| Payments on legal matters | (301) | (7) |
| Balance at end of period | 1,441 | 881 |
| VE Territory Covered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Balance at beginning of period | 102 | 21 |
| Provision for legal matters | 24 | 125 |
| Payments on legal matters | (115) | (44) |
| Balance at end of period | $ 11 | $ 102 |