BUSINESS SEGMENT INFORMATION - Schedule of Segment Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Total depreciation and amortization	$ 87	$ 84	$ 75
Total capital expenditures	103	104	95
TOTAL ASSETS	2,815	2,726
Commercial Truck
Segment Reporting Information [Line Items]
Total depreciation and amortization	68	68	64
Total capital expenditures	82	83	79
Aftermarket, Industrial and Trailer
Segment Reporting Information [Line Items]
Total depreciation and amortization	19	16	11
Total capital expenditures	21	21	16
Operating Segments
Segment Reporting Information [Line Items]
TOTAL ASSETS	2,474	2,353
Operating Segments | Commercial Truck
Segment Reporting Information [Line Items]
TOTAL ASSETS	1,659	1,764
Operating Segments | Aftermarket, Industrial and Trailer
Segment Reporting Information [Line Items]
TOTAL ASSETS	815	589
Corporate
Segment Reporting Information [Line Items]
TOTAL ASSETS	567	633
Segment Reconciling Items
Segment Reporting Information [Line Items]
Total depreciation and amortization	87	84	$ 75
Less: Accounts receivable sold under off-balance sheet factoring programs (4)	$ (226)	$ (260)