Acquisitions and Divestitures - Acquisitions (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Oct. 11, 2018
Business Acquisition [Line Items]
Initial contributions from joint venture	$ 28	$ 0
Consolidated Entity | Adient Aerospace
Business Acquisition [Line Items]
Ownership interest (as percent)			50.01%
Initial contributions from joint venture	$ 28