Business Segment Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) segment	Jun. 30, 2014 USD ($)
Number of reportable segments | segment			2
Total Sales	$ 909	$ 979	$ 2,652	$ 2,833
Commercial Truck & Industrial
Total Sales	682	733	2,020	2,172
Aftermarket & Trailer
Total Sales	227	246	632	661
Operating Segments
Total Sales	909	979	2,652	2,833
Operating Segments | Commercial Truck & Industrial
Total Sales	705	761	2,089	2,251
Operating Segments | Aftermarket & Trailer
Total Sales	233	253	653	680
Eliminations
Total Sales	(29)	(35)	(90)	(98)
Eliminations | Commercial Truck & Industrial
Total Sales	23	28	69	79
Eliminations | Aftermarket & Trailer
Total Sales	$ 6	$ 7	$ 21	$ 19