Earnings Per Share - Schedule of Weighted Average Number of Shares (Detail) - shares shares in Millions |
3 Months Ended | |
|---|---|---|
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| 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 | 390 |
| 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) | 186 | 0 |
| 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) | 38 | 38 |
| 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) | 21 | 31 |