Settlement Guarantee Management - Additional Information (Details) - USD ($) $ in Billions |
12 Months Ended | |
|---|---|---|
Sep. 30, 2025 |
Sep. 30, 2024 |
|
| Settlement Guarantee Management [Abstract] | ||
| Maximum settlement exposure | $ 153.4 | |
| Average daily settlement exposure | 91.2 | |
| Total collateral | $ 8.8 | $ 7.7 |