INVESTMENTS IN NON-CONSOLIDATED JOINT VENTURES - Equity in Earnings of Non-Consolidated Joint Ventures (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Equity in earnings of affiliates	$ 31	$ 27	$ 48
Commercial Truck
Segment Reporting Information [Line Items]
Equity in earnings of affiliates	31	27
Aftermarket, Industrial and Trailer
Segment Reporting Information [Line Items]
Equity in earnings of affiliates	$ 0	$ 0

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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