INCOME TAXES - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning balance	$ 261	$ 269	$ 243
Additions to tax positions recorded during the current year	11	0	0
Additions to tax positions recorded during the prior year	9	0	26
Reductions to tax position recorded in prior years	0	(6)	0
Reductions to tax positions due to lapse of statutory limits	(4)	(1)	(2)
Translation, other	(1)	(1)	2
Unrecognized tax benefits, ending balance	$ 276	$ 261	$ 269