Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 1,190	$ (486)	$ (408)
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	16	(69)	(35)
Realized and unrealized gains (losses) on derivatives	20	(20)	(1)
Pension and postretirement plans	1	0	(2)
Other comprehensive income (loss)	37	(89)	(38)
Total comprehensive income (loss)	1,227	(575)	(446)
Comprehensive income (loss) attributable to noncontrolling interests	81	68	83
Comprehensive income (loss) attributable to Adient	$ 1,146	$ (643)	$ (529)