VARIABLE INTEREST ENTITIES, Not the Primary Beneficiary - Aggregate Assets, Liabilities Exposure to Loss (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Variable Interest Entity [Line Items]
Aggregate assets	$ 77,633	$ 80,951
Aggregate liabilities	67,711	71,519
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Aggregate assets	10,717	10,088
Aggregate liabilities	3,561	3,133
Our risk of loss	182	234
Variable Interest Entity, Not Primary Beneficiary | LIHTC funds
Variable Interest Entity [Line Items]
Aggregate assets	8,187	7,752
Aggregate liabilities	2,846	2,584
Our risk of loss	79	136
Variable Interest Entity, Not Primary Beneficiary | Private Equity Interests
Variable Interest Entity [Line Items]
Aggregate assets	2,416	2,177
Aggregate liabilities	640	448
Our risk of loss	100	90
Variable Interest Entity, Not Primary Beneficiary | Other
Variable Interest Entity [Line Items]
Aggregate assets	114	159
Aggregate liabilities	75	101
Our risk of loss	$ 3	$ 8