Segment Information - EBITDA Schedule (Details) $ in Millions	3 Months Ended						12 Months Ended
	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2021 USD ($) segment	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Segment Reporting Information [Line Items]
Reportable segments | segment							3
Net Sales							$ 13,680	$ 12,670	$ 16,526
Corporate - related costs							22	(16)	(9)
Restructuring and impairment costs							(21)	(238)	(176)
Purchase accounting amortization							(50)	(40)	(44)
Restructuring related charges							(9)	(20)	(31)
Gain (loss) on deconsolidation							(26)	(13)	0
(Gain) on sale of / impairment of nonconsolidated partially owned affiliates							1,214	(231)	0
Depreciation							(285)	(295)	(278)
Stock based compensation							(36)	(15)	(20)
Earnings (loss) before interest and income taxes							1,726	(195)	229
Net financing charges							(311)	(220)	(182)
Other pension income (expense)							24	(14)	(45)
Income (loss) before income taxes							1,439	(429)	2
Impairment of assets held for sale			$ 21	$ 6	$ 12			21	18
Held for sale asset impairments								8
Fixed asset impairment charges						$ 62			66
Loss on business divestitures - net							26	13	0
Tax adjustments							$ 36
Tax credits, recovery period							20 years
Integration-related costs							$ 19	15	3
EMEA
Segment Reporting Information [Line Items]
Impairment of assets held for sale							9
Held for sale asset impairments							1
China
Segment Reporting Information [Line Items]
Impairment of assets held for sale			$ 9
Loss on business divestitures - net							5
BRAZIL
Segment Reporting Information [Line Items]
Tax adjustments							38
Miscellaneous | China
Segment Reporting Information [Line Items]
Intangible asset impairment charge								24
Adient Aerospace
Segment Reporting Information [Line Items]
Gain (loss) on deconsolidation								(4)
YFAI
Segment Reporting Information [Line Items]
Tax adjustments								1	2
Yanfeng
Segment Reporting Information [Line Items]
Loss associated with certain aspects of sale							21
Equity method investment, realized gain (loss) on disposal							1,181
Gain on completion of transaction								12
Yanfeng Adient Seating Co., Ltd. (YFAS)
Segment Reporting Information [Line Items]
Gain on completion of transaction							5
SJA
Segment Reporting Information [Line Items]
Equity method investment, realized gain (loss) on disposal	$ 33	$ 33					33
Futuris
Segment Reporting Information [Line Items]
Integration-related costs									4
Americas
Segment Reporting Information [Line Items]
Impairment of assets held for sale									6
Fixed asset impairment charges									11
Americas | RECARO
Segment Reporting Information [Line Items]
Loss on business divestitures - net								21
EMEA
Segment Reporting Information [Line Items]
Fixed asset impairment charges									55
EMEA | EMEA
Segment Reporting Information [Line Items]
Net Sales							5,564	5,148	6,675
Asia
Segment Reporting Information [Line Items]
Impairment of assets held for sale									12
Reportable Segments | Americas
Segment Reporting Information [Line Items]
Net Sales							6,164	5,889	7,785
Adjusted EBITDA							232	228	210
Reportable Segments | EMEA
Segment Reporting Information [Line Items]
Net Sales							5,564	5,148	6,675
Adjusted EBITDA							277	101	161
Reportable Segments | Asia
Segment Reporting Information [Line Items]
Net Sales							2,123	1,822	2,337
Adjusted EBITDA							486	424	513
Reportable Segments | Asia | China
Segment Reporting Information [Line Items]
Net Sales							642	517	529
Eliminations
Segment Reporting Information [Line Items]
Net Sales							(171)	(189)	(271)
Eliminations | EMEA | EMEA
Segment Reporting Information [Line Items]
Net Sales							(1,453)	(1,423)	(1,835)
Corporate-related costs
Segment Reporting Information [Line Items]
Corporate - related costs							$ (78)	$ (80)	$ (97)