VARIABLE INTEREST ENTITIES VARIABLE INTEREST ENTITIES, Primary Beneficiary - Carrying Value of Assets, Liabilities and Equity (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Assets:
Cash, cash equivalents and cash segregated pursuant to regulations	$ 9,634	$ 5,971	$ 5,941	$ 7,146
Other assets	1,525	1,020
Total assets	47,482	38,830
Liabilities:
Other payables	1,513	747
Total liabilities	40,306	32,187
Noncontrolling interests	62	62
Variable Interest Entity, Primary Beneficiary
Assets:
Total assets	221	159
Liabilities:
Total liabilities	94	23
Variable Interest Entity, Primary Beneficiary | Carrying amount
Assets:
Cash, cash equivalents and cash segregated pursuant to regulations	9	7
Other investments	37	63
Other assets	164	75
Total assets	210	145
Liabilities:
Other payables	76	4
Total liabilities	76	4
Noncontrolling interests	$ 62	$ 60