Segment Information (Details)	3 Months Ended						6 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2019 segment	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) segment	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)
Segment Reporting Information [Line Items]
Reportable segments | segment							3		3
Net Sales									$ 16,526,000,000	$ 17,439,000,000	$ 16,213,000,000
Corporate - related costs									(9,000,000)	(55,000,000)	(16,000,000)
Becoming Adient costs									0	(62,000,000)	(95,000,000)
Separation costs									0	0	(10,000,000)
Restructuring and impairment costs									(176,000,000)	(1,181,000,000)	(46,000,000)
Purchase accounting amortization									(44,000,000)	(69,000,000)	(43,000,000)
Restructuring related charges									(31,000,000)	(61,000,000)	(37,000,000)
Impairment of nonconsolidated partially owned affiliate									0	(358,000,000)	0
Gain on previously-held interest									0	0	151,000,000
Depreciation									(278,000,000)	(393,000,000)	(332,000,000)
Stock based compensation									(20,000,000)	(37,000,000)	(29,000,000)
Earnings (loss) before interest and income taxes									229,000,000	(1,020,000,000)	1,144,000,000
Net financing charges									(182,000,000)	(144,000,000)	(132,000,000)
Other pension income (expense)									(45,000,000)	43,000,000	49,000,000
Income (loss) before income taxes									2,000,000	(1,121,000,000)	1,061,000,000
Fixed asset impairment charges			$ 66,000,000						66,000,000
Asset impairment charge	$ 12,000,000		66,000,000
Impairment of goodwill	$ 0		0					$ 0		299,000,000
Impairment of assets held for sale				$ 6,000,000					18,000,000
Depreciation									278,000,000	400,000,000	337,000,000
Integration-related costs									3,000,000
Income tax provision (benefit)									410,000,000	480,000,000	99,000,000
Initial funding											12,000,000
Cost of sales									15,725,000,000	16,535,000,000	14,816,000,000
YFAI
Segment Reporting Information [Line Items]
Impairment of nonconsolidated partially owned affiliate					$ (358,000,000)					(358,000,000)
Gain on previously-held interest											151,000,000
Tax adjustments									2,000,000
Corporate joint venture | YFAI
Segment Reporting Information [Line Items]
Income tax provision (benefit)										8,000,000
Futuris
Segment Reporting Information [Line Items]
Integration-related costs									4,000,000	22,000,000	3,000,000
Restructuring Related Charges
Segment Reporting Information [Line Items]
Depreciation										7,000,000
Becoming Adient Costs
Segment Reporting Information [Line Items]
Stock based compensation										10,000,000	16,000,000
Depreciation											5,000,000
Restatement Adjustment
Segment Reporting Information [Line Items]
Prior period adjustment										8,000,000
Cost of sales		$ 8,000,000
Americas
Segment Reporting Information [Line Items]
Fixed asset impairment charges									11,000,000
Impairment of goodwill										71,000,000
Impairment of assets held for sale									6,000,000
EMEA
Segment Reporting Information [Line Items]
Fixed asset impairment charges									55,000,000
Impairment of goodwill										228,000,000
Asia
Segment Reporting Information [Line Items]
Impairment of goodwill										0
Impairment of assets held for sale									12,000,000
Seating, Seat Structures and Mechanisms
Segment Reporting Information [Line Items]
Fixed asset impairment charges			62,000,000		$ 787,000,000					768,000,000
Asset impairment charge			$ 66,000,000							787,000,000
Pre-tax impairment charge										1,086,000,000
Impairment of goodwill						$ 299,000,000				299,000,000
Impairment of assets held for sale										49,000,000
Consulting fees										11,000,000
Operating segments | Americas
Segment Reporting Information [Line Items]
Net Sales									7,785,000,000	7,664,000,000	7,290,000,000
Adjusted EBITDA									210,000,000	302,000,000	758,000,000
Depreciation									109,000,000	141,000,000	118,000,000
Operating segments | EMEA
Segment Reporting Information [Line Items]
Net Sales									6,675,000,000	7,436,000,000	7,044,000,000
Adjusted EBITDA									161,000,000	364,000,000	424,000,000
Depreciation									126,000,000	204,000,000	174,000,000
Operating segments | Asia
Segment Reporting Information [Line Items]
Net Sales									2,337,000,000	2,659,000,000	2,129,000,000
Adjusted EBITDA									513,000,000	625,000,000	554,000,000
Depreciation									43,000,000	45,000,000	36,000,000
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Sales									(271,000,000)	(320,000,000)	(250,000,000)
Corporate-related costs
Segment Reporting Information [Line Items]
Corporate - related costs									$ (97,000,000)	$ (95,000,000)	$ (135,000,000)