INCOME TAXES - Components of the Benefit (Provision) for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Current tax expense:
U.S.									$ 1	$ 24	$ 1
Foreign									40	51	11
State and local									1	0	2
Total current tax expense									42	75	14
Deferred tax expense (benefit):
U.S.									34	76	28
Foreign									6	(5)	9
State and local									0	3	1
Total deferred tax expense									40	74	38
Income tax expense	$ 13	$ 21	$ 27	$ 21	$ 18	$ 26	$ 22	$ 83	$ 82	$ 149	$ 52