Earnings Per Share - Schedule of Weighted Average Number of Shares (Details) - shares shares in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
Jun. 30, 2025 |
Jun. 30, 2024 |
|
| Class B-1 common stock | ||||
| Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items] | ||||
| Weighted-average as-converted common stock used in income allocation (in shares) | 8 | 155 | 8 | 312 |
| Class B-2 common stock | ||||
| Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items] | ||||
| Weighted-average as-converted common stock used in income allocation (in shares) | 185 | 118 | 185 | 39 |
| Class C common stock | ||||
| Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items] | ||||
| Weighted-average as-converted common stock used in income allocation (in shares) | 36 | 114 | 37 | 63 |
| Participating securities | ||||
| Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items] | ||||
| Weighted-average as-converted common stock used in income allocation (in shares) | 20 | 30 | 20 | 31 |