Legal Matters - Legal Matters - Schedule of Accrued Litigation for Both Covered and Non-Covered Litigation (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Sep. 30, 2024 |
Sep. 30, 2023 |
|
| Loss Contingency Accrual [Roll Forward] | ||
| Balance as of beginning of period | $ 1,751 | $ 1,456 |
| Balance as of end of period | 1,727 | 1,751 |
| Uncovered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Provision for legal matters | 322 | 21 |
| Covered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Provision for legal matters | 248 | 1,024 |
| Payments on legal matters | (594) | (750) |
| U.S. Covered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Balance as of beginning of period | 1,621 | 1,441 |
| Provision for legal matters | 140 | 906 |
| Payments on legal matters | (224) | (726) |
| Balance as of end of period | 1,537 | 1,621 |
| VE Territory Covered Litigation | ||
| Loss Contingency Accrual [Roll Forward] | ||
| Balance as of beginning of period | 110 | 11 |
| Provision for legal matters | 108 | 118 |
| Payments on legal matters | (146) | (19) |
| Balance as of end of period | $ 72 | $ 110 |