VARIABLE INTEREST ENTITIES VARIABLE INTEREST ENTITIES, Primary Beneficiary - Carrying Value of Assets, Liabilities and Equity (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Assets:
Cash and cash equivalents and assets segregated for regulatory purposes and restricted cash	$ 16,449	$ 9,634	$ 5,971	$ 5,941
Other assets	2,257	2,060
Total assets	61,891	47,482
Liabilities:
Other payables	1,701	1,513
Total liabilities	53,588	40,306
Noncontrolling interests	58	62
Variable Interest Entity, Primary Beneficiary
Assets:
Total assets	192	221
Liabilities:
Total liabilities	71	94
Variable Interest Entity, Primary Beneficiary | Carrying amount
Assets:
Cash and cash equivalents and assets segregated for regulatory purposes and restricted cash	10	9
Other investments	63	37
Other assets	105	164
Total assets	178	210
Liabilities:
Other payables	45	76
Total liabilities	45	76
Noncontrolling interests	$ 58	$ 62