Business Segment Information - Schedule of Segment Assets (Details) - USD ($) $ in Millions	Jun. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Total assets	$ 2,712	$ 2,494
Operating Segments
Segment Reporting Information [Line Items]
Total assets	2,084	1,869
Operating Segments | Commercial Truck & Industrial
Segment Reporting Information [Line Items]
Total assets	1,618	1,433
Operating Segments | Aftermarket & Trailer
Segment Reporting Information [Line Items]
Total assets	466	436
Corporate
Segment Reporting Information [Line Items]
Total assets	916	845
Segment Reconciling Items
Segment Reporting Information [Line Items]
Less: Accounts receivable sold under off-balance sheet factoring programs	$ (288)	$ (220)