Business Segment Information - Summary of Segment Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2017 USD ($) segment	Mar. 31, 2016 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			2
Total Sales	$ 806	$ 821	$ 1,505	$ 1,630
Commercial Truck & Industrial
Segment Reporting Information [Line Items]
Total Sales	601	610	1,122	1,223
Aftermarket & Trailer
Segment Reporting Information [Line Items]
Total Sales	205	211	383	407
Operating Segments
Segment Reporting Information [Line Items]
Total Sales			1,505	1,630
Operating Segments | Commercial Truck & Industrial
Segment Reporting Information [Line Items]
Total Sales	620	631	1,159	1,264
Operating Segments | Aftermarket & Trailer
Segment Reporting Information [Line Items]
Total Sales	215	218	399	421
Eliminations
Segment Reporting Information [Line Items]
Total Sales	(29)	(28)	(53)	(55)
Eliminations | Commercial Truck & Industrial
Segment Reporting Information [Line Items]
Total Sales	19	21	37	41
Eliminations | Aftermarket & Trailer
Segment Reporting Information [Line Items]
Total Sales	$ 10	$ 7	$ 16	$ 14