Stockholders' Equity - Schedule of As-Converted Class B Common Stock (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions |
6 Months Ended | |
|---|---|---|
Mar. 31, 2023 |
Mar. 31, 2022 |
|
| Stockholders' Equity Note [Abstract] | ||
| Reduction in equivalent number of as-converted shares of class A common stock (in shares) | 2 | 1 |
| Effective price per share (in dollars per share) | $ 209.14 | $ 217.61 |
| Deposits under the U.S. retrospective responsibility plan | $ 350 | $ 250 |