Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Sales	$ 1,038	$ 903
Trade receivables, net	509		$ 566
U.S.
Disaggregation of Revenue [Line Items]
Sales	589
Canada
Disaggregation of Revenue [Line Items]
Sales	18
Mexico
Disaggregation of Revenue [Line Items]
Sales	58
Total North America
Disaggregation of Revenue [Line Items]
Sales	665
Sweden
Disaggregation of Revenue [Line Items]
Sales	74
Italy
Disaggregation of Revenue [Line Items]
Sales	61
United Kingdom
Disaggregation of Revenue [Line Items]
Sales	44
Other Europe
Disaggregation of Revenue [Line Items]
Sales	22
Total Europe
Disaggregation of Revenue [Line Items]
Sales	201
Brazil
Disaggregation of Revenue [Line Items]
Sales	50
China
Disaggregation of Revenue [Line Items]
Sales	41
India
Disaggregation of Revenue [Line Items]
Sales	57
Other Asia-Pacific
Disaggregation of Revenue [Line Items]
Sales	24
Commercial Truck & Trailer
Disaggregation of Revenue [Line Items]
Sales	786	678
Commercial Truck & Trailer | U.S.
Disaggregation of Revenue [Line Items]
Sales	385
Commercial Truck & Trailer | Canada
Disaggregation of Revenue [Line Items]
Sales	0
Commercial Truck & Trailer | Mexico
Disaggregation of Revenue [Line Items]
Sales	54
Commercial Truck & Trailer | Total North America
Disaggregation of Revenue [Line Items]
Sales	439
Commercial Truck & Trailer | Sweden
Disaggregation of Revenue [Line Items]
Sales	74
Commercial Truck & Trailer | Italy
Disaggregation of Revenue [Line Items]
Sales	57
Commercial Truck & Trailer | United Kingdom
Disaggregation of Revenue [Line Items]
Sales	41
Commercial Truck & Trailer | Other Europe
Disaggregation of Revenue [Line Items]
Sales	3
Commercial Truck & Trailer | Total Europe
Disaggregation of Revenue [Line Items]
Sales	175
Commercial Truck & Trailer | Brazil
Disaggregation of Revenue [Line Items]
Sales	50
Commercial Truck & Trailer | China
Disaggregation of Revenue [Line Items]
Sales	41
Commercial Truck & Trailer | India
Disaggregation of Revenue [Line Items]
Sales	57
Commercial Truck & Trailer | Other Asia-Pacific
Disaggregation of Revenue [Line Items]
Sales	24
Aftermarket & Industrial
Disaggregation of Revenue [Line Items]
Sales	252	$ 225
Aftermarket & Industrial | U.S.
Disaggregation of Revenue [Line Items]
Sales	204
Aftermarket & Industrial | Canada
Disaggregation of Revenue [Line Items]
Sales	18
Aftermarket & Industrial | Mexico
Disaggregation of Revenue [Line Items]
Sales	4
Aftermarket & Industrial | Total North America
Disaggregation of Revenue [Line Items]
Sales	226
Aftermarket & Industrial | Sweden
Disaggregation of Revenue [Line Items]
Sales	0
Aftermarket & Industrial | Italy
Disaggregation of Revenue [Line Items]
Sales	4
Aftermarket & Industrial | United Kingdom
Disaggregation of Revenue [Line Items]
Sales	3
Aftermarket & Industrial | Other Europe
Disaggregation of Revenue [Line Items]
Sales	19
Aftermarket & Industrial | Total Europe
Disaggregation of Revenue [Line Items]
Sales	26
Aftermarket & Industrial | Brazil
Disaggregation of Revenue [Line Items]
Sales	0
Aftermarket & Industrial | China
Disaggregation of Revenue [Line Items]
Sales	0
Aftermarket & Industrial | India
Disaggregation of Revenue [Line Items]
Sales	0
Aftermarket & Industrial | Other Asia-Pacific
Disaggregation of Revenue [Line Items]
Sales	$ 0