Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents (Details) - USD ($) $ in Millions |
Sep. 30, 2024 |
Sep. 30, 2023 |
Sep. 30, 2022 |
Sep. 30, 2021 |
|---|---|---|---|---|
| Restricted Cash and Cash Equivalents Items [Line Items] | ||||
| Cash and cash equivalents | $ 11,975 | $ 16,286 | ||
| Cash, cash equivalents, restricted cash and restricted cash equivalents | 19,763 | 21,990 | $ 20,377 | $ 19,799 |
| U.S. litigation escrow | ||||
| Restricted Cash and Cash Equivalents Items [Line Items] | ||||
| Restricted cash and restricted cash equivalents: | 3,089 | 1,764 | ||
| Customer collateral | ||||
| Restricted Cash and Cash Equivalents Items [Line Items] | ||||
| Restricted cash and restricted cash equivalents: | 3,524 | 3,005 | ||
| Prepaid expenses and other current assets | ||||
| Restricted Cash and Cash Equivalents Items [Line Items] | ||||
| Restricted cash and restricted cash equivalents: | $ 1,175 | $ 935 |