COMMITMENTS, CONTINGENCIES AND GUARANTEES, Summary of Off-Balance Sheet Risks (Details) - USD ($) $ in Millions	Dec. 31, 2023	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
SBL and other consumer lines of credit	$ 39,731	$ 123
Commercial lines of credit	4,144	38,791
Unfunded lending commitments	869	4,131
Standby letters of credit	$ 112	$ 936