VARIABLE INTEREST ENTITIES, Primary Beneficiary - Carrying Value of Assets, Liabilities and Equity (Details) - USD ($) $ in Millions	Jun. 30, 2022	Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020
Assets:
Cash and cash equivalents and assets segregated for regulatory purposes and restricted cash	$ 20,209	$ 16,449	$ 11,864	$ 9,634
Other assets	2,391	2,257
Total assets	86,111	61,891
Liabilities:
Other payables	1,708	1,701
Total liabilities	76,619	53,588
Noncontrolling interests	(23)	58
Variable Interest Entity, Primary Beneficiary
Assets:
Total assets	91	192
Liabilities:
Total liabilities	34	71
Variable Interest Entity, Primary Beneficiary | Carrying amount
Assets:
Cash and cash equivalents and assets segregated for regulatory purposes and restricted cash	5	10
Other investments	0	63
Other assets	62	105
Total assets	67	178
Liabilities:
Other payables	0	45
Total liabilities	0	45
Noncontrolling interests	$ (24)	$ 58