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, 2023 |
Sep. 30, 2022 |
|
| Equity [Abstract] | ||
| Reduction in equivalent number of class A common stock (in shares) | 5 | 4 |
| Effective price per share (in dollars per share) | $ 221.33 | $ 205.06 |
| Deposits into the U.S. litigation escrow account | $ 1,000 | $ 850 |