Stockholders' Equity - Share Repurchases in the Open Market (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
Jun. 30, 2025 |
Jun. 30, 2024 |
Sep. 30, 2024 |
|
| Equity, Class of Treasury Stock [Line Items] | |||||
| Total cost | $ 4,828 | $ 4,770 | $ 13,241 | $ 11,163 | |
| Unsettled repurchases | $ 4,907 | $ 4,907 | $ 4,909 | ||
| Class A common stock | |||||
| Equity, Class of Treasury Stock [Line Items] | |||||
| Shares repurchased in the open market (in shares) | 14 | 17 | 40 | 42 | |
| Average repurchase cost per share (in dollars per share) | $ 349.24 | $ 276.75 | $ 330.39 | $ 263.91 | |
| Total cost | $ 4,828 | $ 4,770 | $ 13,241 | $ 11,163 | |
| Unsettled repurchases | $ 61 | $ 200 | $ 61 | $ 200 | |