Business Segment Information - Segment Income Attributable to Parent (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Interest expense, net	$ (21)	$ (21)	$ (42)	$ (43)
Provision for income taxes	(13)	(7)	(19)	(14)
Depreciation and amortization			(37)	(31)
Noncontrolling interests	(1)	0	(2)	(1)
Asset impairment charges			(3)	0
Restructuring costs	(4)	(2)	(4)	(3)
Net income from continuing operations	22	33	37	61
Operating Segments
Segment Reporting Information [Line Items]
Segment adjusted EBITDA	84	84	148	156
Operating Segments | Commercial Truck & Industrial
Segment Reporting Information [Line Items]
Segment adjusted EBITDA	54	56	96	108
Operating Segments | Aftermarket & Trailer
Segment Reporting Information [Line Items]
Segment adjusted EBITDA	30	28	52	48
Segment Reconciling Items
Segment Reporting Information [Line Items]
Unallocated legacy and corporate costs, net	(2)	(3)	(2)	1
Interest expense, net	(21)	(21)	(42)	(43)
Provision for income taxes	(13)	(7)	(19)	(14)
Depreciation and amortization	(20)	(16)	(37)	(31)
Noncontrolling interests	(1)	0	(2)	(1)
Loss on sale of receivables	(1)	(2)	(2)	(4)
Asset impairment charges	0	0	(3)	0
Restructuring costs	$ (4)	$ (2)	$ (4)	$ (3)