FINANCIAL INSTRUMENTS - Fair Value of Financial Instruments by the Valuation Hierarchy (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Level 1
Derivatives, Fair Value [Line Items]
Cash and cash equivalents	$ 108	$ 115
Level 2
Derivatives, Fair Value [Line Items]
Cash and cash equivalents	0	0
Level 3
Derivatives, Fair Value [Line Items]
Cash and cash equivalents	0	0
Foreign Exchange Forward | Level 1
Derivatives, Fair Value [Line Items]
Foreign contracts and cross-currency swaps (other assets)	0	0
Foreign contracts and cross-currency swaps (other liabilities)	0	0
Foreign Exchange Forward | Level 2
Derivatives, Fair Value [Line Items]
Foreign contracts and cross-currency swaps (other assets)	0	2
Foreign contracts and cross-currency swaps (other liabilities)	0	0
Foreign Exchange Forward | Level 3
Derivatives, Fair Value [Line Items]
Foreign contracts and cross-currency swaps (other assets)	0	0
Foreign contracts and cross-currency swaps (other liabilities)	0	0
Foreign Currency Option Contracts | Level 1
Derivatives, Fair Value [Line Items]
Foreign contracts and cross-currency swaps (other assets)	0	0
Foreign Currency Option Contracts | Level 2
Derivatives, Fair Value [Line Items]
Foreign contracts and cross-currency swaps (other assets)	0	0
Foreign Currency Option Contracts | Level 3
Derivatives, Fair Value [Line Items]
Foreign contracts and cross-currency swaps (other assets)	0	0
Cross-currency swap | Level 1
Derivatives, Fair Value [Line Items]
Foreign contracts and cross-currency swaps (other assets)	0	0
Foreign contracts and cross-currency swaps (other liabilities)	0
Cross-currency swap | Level 2
Derivatives, Fair Value [Line Items]
Foreign contracts and cross-currency swaps (other assets)	10	6
Foreign contracts and cross-currency swaps (other liabilities)	5
Cross-currency swap | Level 3
Derivatives, Fair Value [Line Items]
Foreign contracts and cross-currency swaps (other assets)	0	$ 0
Foreign contracts and cross-currency swaps (other liabilities)	$ 0