COMMITMENTS, CONTINGENCIES AND GUARANTEES, Summary of Off-Balance Sheet Risks (Details) - USD ($) $ in Millions |
Jun. 30, 2025 |
Sep. 30, 2024 |
|---|---|---|
| Commitments and Contingencies Disclosure [Abstract] | ||
| SBL and other consumer lines of credit | $ 53,468 | $ 44,057 |
| Commercial lines of credit | 5,262 | 4,630 |
| Unfunded lending commitments | 595 | 640 |
| Standby letters of credit | $ 160 | $ 111 |