Equity and Noncontrolling Interests - Schedule of Stockholders Equity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance	$ 2,616	$ 2,509	$ 2,546	$ 2,375
Net income (loss)	(56)	1	(24)	27
Foreign currency translation adjustments	(96)	33	38	128
Realized and unrealized gains (losses) on derivatives	(6)	14	3	39
Dividends attributable to noncontrolling interests	(14)	(2)	(18)	(6)
Repurchases of common stock	(50)	(30)	(150)	(30)
Share based compensation and other	8	7	7	(1)
Stockholders' equity, ending balance	2,402	2,532	2,402	2,532
Shareholders' Equity Attributable to Adient
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance	2,285	2,192	2,228	2,073
Net income (loss)	(70)	(15)	(50)	(3)
Foreign currency translation adjustments	(92)	29	37	119
Realized and unrealized gains (losses) on derivatives	(6)	14	3	39
Repurchases of common stock	(50)	(30)	(150)	(30)
Share based compensation and other	8	7	7	(1)
Stockholders' equity, ending balance	2,075	2,197	2,075	2,197
Ordinary Shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance	0	0	0	0
Stockholders' equity, ending balance	0	0	0	0
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance	3,872	4,018	3,973	4,026
Repurchases of common stock	(50)	(30)	(150)	(30)
Share based compensation and other	8	7	7	(1)
Stockholders' equity, ending balance	3,830	3,995	3,830	3,995
Retained Earnings (Accumulated Deficit)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance	(883)	(1,096)	(903)	(1,108)
Net income (loss)	(70)	(15)	(50)	(3)
Stockholders' equity, ending balance	(953)	(1,111)	(953)	(1,111)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance	(704)	(730)	(842)	(845)
Foreign currency translation adjustments	(92)	29	37	119
Realized and unrealized gains (losses) on derivatives	(6)	14	3	39
Stockholders' equity, ending balance	(802)	(687)	(802)	(687)
Shareholders' Equity Attributable to Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' equity, beginning balance	331	317	318	302
Net income (loss)	14	16	26	30
Foreign currency translation adjustments	(4)	4	1	9
Dividends attributable to noncontrolling interests	(14)	(2)	(18)	(6)
Repurchases of common stock		0		0
Share based compensation and other	0	0	0	0
Stockholders' equity, ending balance	$ 327	$ 335	$ 327	$ 335