Restructuring Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016	Sep. 30, 2016
Restructuring Reserve [Roll Forward]
Beginning balance			$ 16	$ 10
Charges to continuing operations	$ 4	$ 2	4	3
Cash payments – continuing operations			(7)	(4)
Other			(1)
Ending balance	12	9	12	9
Less: non-current restructuring reserves	(1)	(3)	(1)	(3)	$ (2)
Restructuring reserves – current	11	6	11	6	$ 14
Employee Termination Benefits
Restructuring Reserve [Roll Forward]
Beginning balance			15	10
Charges to continuing operations			4	2
Cash payments – continuing operations			(7)	(4)
Other			(1)
Ending balance	11	8	11	8
Less: non-current restructuring reserves	(1)	(3)	(1)	(3)
Restructuring reserves – current	10	5	10	5
Employee Termination Benefits | Europe | Commercial Truck and Industrial, Aftermarket and Trailer
Restructuring Reserve [Roll Forward]
Charges to continuing operations			4
Employee Termination Benefits | China | Commercial Truck and Industrial, Aftermarket and Trailer
Restructuring Reserve [Roll Forward]
Charges to continuing operations				3
Plant Shutdown & Other
Restructuring Reserve [Roll Forward]
Beginning balance			1	0
Charges to continuing operations			0	1
Cash payments – continuing operations			0	0
Other			0
Ending balance	1	1	1	1
Less: non-current restructuring reserves	0	0	0	0
Restructuring reserves – current	$ 1	$ 1	$ 1	$ 1