Basis of Presentation and Summary of Significant Accounting Policies - Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income (loss) attributable to Adient	$ (17)	$ (216)
Denominator:
Shares outstanding (in shares)	93.5	93.2
Effect of dilutive securities (in shares)	0.0	0.0
Diluted shares (in shares)	93.5	93.2
Earnings per share, basic (in dollars per share)	$ (0.18)	$ (2.32)
Earnings per share, diluted (in dollars per share)	$ (0.18)	$ (2.32)
Antidilutive securities excluded from computation of diluted earnings per share	0.0	0.0