VARIABLE INTEREST ENTITIES, Not the Primary Beneficiary - Aggregate Assets, Liabilities Exposure to Loss (Details) - USD ($) $ in Millions	Mar. 31, 2022	Sep. 30, 2021
Variable Interest Entity [Line Items]
Aggregate assets	$ 73,101	$ 61,891
Aggregate liabilities	64,492	53,588
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Aggregate assets	14,385	14,869
Aggregate liabilities	2,646	2,482
Our risk of loss	142	163
Private Equity Interests | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Aggregate assets	6,638	7,318
Aggregate liabilities	103	47
Our risk of loss	118	82
LIHTC funds | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Aggregate assets	7,588	7,032
Aggregate liabilities	2,421	2,280
Our risk of loss	21	71
Other | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Aggregate assets	159	519
Aggregate liabilities	122	155
Our risk of loss	$ 3	$ 10