GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS, NET, Intangible Assets, by Type (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Intangible Assets [Line Items]
Gross carrying value, finite-lived intangible assets	$ 206	$ 209
Accumulated amortization, finite-lived intangible assets	(72)	(62)
Customer relationships
Intangible Assets [Line Items]
Gross carrying value, finite-lived intangible assets	134	134
Accumulated amortization, finite-lived intangible assets	(61)	(50)
Trade name
Intangible Assets [Line Items]
Gross carrying value, finite-lived intangible assets	10	12
Accumulated amortization, finite-lived intangible assets	(4)	(5)
Seller relationship agreements
Intangible Assets [Line Items]
Gross carrying value, finite-lived intangible assets	4	5
Accumulated amortization, finite-lived intangible assets	(2)	(3)
Other
Intangible Assets [Line Items]
Gross carrying value, finite-lived intangible assets	6	6
Accumulated amortization, finite-lived intangible assets	(5)	(4)
Customer relationships
Intangible Assets [Line Items]
Gross carrying value, indefinite-lived assets	52	52
Accumulated amortization, indefinite-lived assets	$ 0	$ 0