INVESTMENTS IN NON-CONSOLIDATED JOINT VENTURES - Additional Information (Details) - USD ($) $ in Millions		12 Months Ended
Sep. 30, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Dividends/Distributions received from the company's non-consolidated joint ventures		$ 23	$ 17	$ 44
Sales to non-consolidated joint ventures		9	7	2
Sales excluded from non-consolidated joint ventures through intercompany eliminations		193	196	138
Purchases from non-consolidated joint ventures		940	843	787
Lease and services payments from non-consolidated joint ventures		12	11	6
Amounts due from non-consolidated joint ventures		34	43
Amounts due to non-consolidated joint ventures		80	110
Automotive Axles Limited (Commercial Truck)
Schedule of Equity Method Investments [Line Items]
Fair value of investment		$ 75	$ 91
Meritor WABCO JV \| WABCO Holdings Inc.
Schedule of Equity Method Investments [Line Items]
Dividends/Distributions received from the company's non-consolidated joint ventures	$ 8			$ 36

The amounts due from non-consolidated joint ventures as of the balance sheet date.

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The amounts due to non-consolidated joint ventures as of the balance sheet date.

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Sales excluded from non-consolidated joint ventures through intercompany eliminations.

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The amount of leases and services income received from non-consolidated joint ventures during the reporting period.

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Total purchases of goods and services by the reporting entity from its non-consolidated joint ventures during the reporting period, in the normal course of business, reduced by purchase returns and allowances, and purchase discounts.

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Total revenue from sale of goods and services rendered from the reporting entity to its non-consolidated joint ventures during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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Amount of distribution received from equity method investee for return on investment, classified as operating activities. Excludes distribution for return of investment, classified as investing activities.

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Fair value portion of investments accounted under the equity method.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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