Business Segment Information - Summary of Segment Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) segment	Jun. 30, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			2
Total Sales	$ 920	$ 841	$ 2,425	$ 2,471
Commercial Truck & Industrial
Segment Reporting Information [Line Items]
Total Sales	704	623	1,826	1,846
Aftermarket & Trailer
Segment Reporting Information [Line Items]
Total Sales	216	218	599	625
Operating Segments
Segment Reporting Information [Line Items]
Total Sales	920	841	2,425	2,471
Operating Segments | Commercial Truck & Industrial
Segment Reporting Information [Line Items]
Total Sales	728	640	1,887	1,904
Operating Segments | Aftermarket & Trailer
Segment Reporting Information [Line Items]
Total Sales	228	227	627	648
Eliminations
Segment Reporting Information [Line Items]
Total Sales	(36)	(26)	(89)	(81)
Eliminations | Commercial Truck & Industrial
Segment Reporting Information [Line Items]
Total Sales	24	17	61	58
Eliminations | Aftermarket & Trailer
Segment Reporting Information [Line Items]
Total Sales	$ 12	$ 9	$ 28	$ 23