Business Segment Information - Schedule of Segment Assets (Details) - USD ($) $ in Millions	Mar. 31, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Total assets	$ 2,595	$ 2,782
Operating Segments
Segment Reporting Information [Line Items]
Total assets	2,311	2,174
Operating Segments | Commercial Truck & Trailer
Segment Reporting Information [Line Items]
Total assets	1,820	1,708
Operating Segments | Aftermarket & Industrial
Segment Reporting Information [Line Items]
Total assets	491	466
Corporate
Segment Reporting Information [Line Items]
Total assets	563	869
Segment Reconciling Items
Segment Reporting Information [Line Items]
Less: Accounts receivable sold under off-balance sheet factoring programs	$ (279)	$ (261)