Stockholders' Equity - Schedule of As-Converted Class B Common Stock (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions |
12 Months Ended | |
|---|---|---|
Sep. 30, 2022 |
Sep. 30, 2021 |
|
| Equity [Abstract] | ||
| Reduction in equivalent number of class A common stock (in shares) | 4 | |
| Effective price per share (in dollars per share) | $ 205.06 | |
| Deposits under the U.S. retrospective responsibility plan | $ 850 | $ 0 |