Business Segment Information - Summary of Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Sales	$ 984	$ 889
External Sales
Segment Reporting Information [Line Items]
Sales	984	889
Intersegment Sales
Segment Reporting Information [Line Items]
Sales	0	0
Commercial Truck
Segment Reporting Information [Line Items]
Sales	748	660
Aftermarket & Industrial
Segment Reporting Information [Line Items]
Sales	236	229
Reportable Segments | Commercial Truck
Segment Reporting Information [Line Items]
Sales	785	691
Reportable Segments | Commercial Truck | External Sales
Segment Reporting Information [Line Items]
Sales	748	660
Reportable Segments | Commercial Truck | Intersegment Sales
Segment Reporting Information [Line Items]
Sales	37	31
Reportable Segments | Aftermarket & Industrial
Segment Reporting Information [Line Items]
Sales	241	234
Reportable Segments | Aftermarket & Industrial | External Sales
Segment Reporting Information [Line Items]
Sales	236	229
Reportable Segments | Aftermarket & Industrial | Intersegment Sales
Segment Reporting Information [Line Items]
Sales	5	5
Eliminations
Segment Reporting Information [Line Items]
Sales	(42)	(36)
Eliminations | External Sales
Segment Reporting Information [Line Items]
Sales	0	0
Eliminations | Intersegment Sales
Segment Reporting Information [Line Items]
Sales	$ (42)	$ (36)