INCOME TAXES - Summary of the Tax Effects of Temporary Differences (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Accrued compensation and benefits	$ 19	$ 15
Accrued product warranties	11	11
Inventory costs	7	6
Receivables	8	8
Environmental	8	28
Accrued retiree healthcare benefits	16	21
Retirement pension plans	59	41
Property	7	10
Loss and credit carryforwards	230	278
Other	18	19
Sub-total	383	437
Less: Valuation allowances	(207)	(236)
Deferred income taxes - asset	176	201
Taxes on undistributed income	(10)	(14)
Intangible assets	(51)	(54)
Debt basis difference	(8)	(9)
Deferred income taxes - liability	(69)	(77)
Net deferred income tax assets	$ 107	$ 124