VARIABLE INTEREST ENTITIES, Not the Primary Beneficiary - Aggregate Assets, Liabilities Exposure to Loss (Details) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021
Variable Interest Entity [Line Items]
Aggregate assets	$ 68,461	$ 61,891
Aggregate liabilities	59,809	53,588
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Aggregate assets	15,251	14,869
Aggregate liabilities	2,729	2,482
Our risk of loss	111	163
Private Equity Interests | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Aggregate assets	7,163	7,318
Aggregate liabilities	88	47
Our risk of loss	86	82
LIHTC funds | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Aggregate assets	7,374	7,032
Aggregate liabilities	2,465	2,280
Our risk of loss	14	71
Other | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Aggregate assets	714	519
Aggregate liabilities	176	155
Our risk of loss	$ 11	$ 10