BANK DEPOSITS, Schedule Maturities of Certificates of Deposit (Details) - USD ($) $ in Millions	Jun. 30, 2022	Sep. 30, 2021
Scheduled maturities of certificates of deposit, denominations greater than or equal to $100,000 [Abstract]
Three months or less	$ 225	$ 22
Over three through six months	145	21
Over six through twelve months	131	32
Over one through two years	103	93
Over two through three years	25	37
Over three through four years	7	6
Over four through five years	6	9
Total certificates of deposit	642	220
Scheduled maturities of certificates of deposit, denominations less than 100,000 [Abstract]
Three months or less	31	87
Over three through six months	88	76
Over six through twelve months	43	54
Over one through two years	159	170
Over two through three years	149	166
Over three through four years	5	99
Over four through five years	4	6
Total certificates of deposit	$ 479	$ 658