VARIABLE INTEREST ENTITIES, Not the Primary Beneficiary - Aggregate Assets, Liabilities Exposure to Loss (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Variable Interest Entity [Line Items]
Aggregate assets	$ 78,360	$ 80,951
Aggregate liabilities	68,173	71,519
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Aggregate assets	11,243	10,088
Aggregate liabilities	3,703	3,133
Our risk of loss	217	234
Variable Interest Entity, Not Primary Beneficiary | LIHTC
Variable Interest Entity [Line Items]
Aggregate assets	8,451	7,752
Aggregate liabilities	2,964	2,584
Our risk of loss	113	136
Variable Interest Entity, Not Primary Beneficiary | Private Equity Interests
Variable Interest Entity [Line Items]
Aggregate assets	2,591	2,177
Aggregate liabilities	655	448
Our risk of loss	101	90
Variable Interest Entity, Not Primary Beneficiary | Other
Variable Interest Entity [Line Items]
Aggregate assets	201	159
Aggregate liabilities	84	101
Our risk of loss	$ 3	$ 8