Income Taxes (Details) - USD ($)		1 Months Ended		3 Months Ended						6 Months Ended		12 Months Ended
	Sep. 22, 2017	Jul. 31, 2017	Oct. 31, 2016	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Mar. 31, 2018	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Tax Contingency [Line Items]
Net operating loss carryforwards				$ 3,500,000,000								$ 3,500,000,000
Net operating loss carryforwards set to expire between 2020 and 2039				1,800,000,000								1,800,000,000
Operating loss carryforwards, valuation allowance				2,300,000,000								2,300,000,000
Income tax expense (benefit), adjustment					$ 10,000,000		$ (9,000,000)
Deferred tax asset, increase (decrease) of valuation allowance													$ (76,000,000)
Unrecognized tax benefits				414,000,000				$ 288,000,000			$ 288,000,000	414,000,000	288,000,000	$ 193,000,000	$ 596,000,000
Unrecognized tax benefits that would impact effective tax rate				119,000,000								119,000,000
Net accrued interest				10,000,000				5,000,000			5,000,000	10,000,000	5,000,000	3,000,000
Undistributed foreign earnings				15,500,000,000								15,500,000,000
Undistributed foreign earnings deemed permanently reinvested				451,000,000								451,000,000
Income taxes paid			$ 16,000,000									102,000,000	$ 139,000,000	148,000,000
Tax rate					24.90%					26.00%
Change in effective tax rate (as percent)													24.50%
Change in effective tax rate, non-cash tax expense													$ 106,000,000
Non-cash estimated tax expense													100,000,000
Estimated cash tax expense													4,000,000
Deferred tax liability related to intangible asset	$ 57,000,000	$ 69,000,000
Acquisition related costs	3,000,000													3,000,000
Restructuring and impairment costs												176,000,000	1,181,000,000	46,000,000
Fixed asset impairment charges						$ 66,000,000						66,000,000
Goodwill Impairment						2,000,000
Impairment of nonconsolidated partially owned affiliate												0	358,000,000	0
Asset impairment charge				12,000,000		66,000,000
Impairment				$ 0		0					0		299,000,000
Goodwill
Income Tax Contingency [Line Items]
Goodwill Impairment									$ 20,000,000
Assets held for sale | Detroit Properties and Airplanes
Income Tax Contingency [Line Items]
Goodwill Impairment											14,000,000
Asset impairment charge											$ 49,000,000		49,000,000
YFAI
Income Tax Contingency [Line Items]
Impairment of nonconsolidated partially owned affiliate								358,000,000					358,000,000
Tax from nonconsolidated partially owned affiliates								36,000,000
Seating, Seat Structures and Mechanisms
Income Tax Contingency [Line Items]
Fixed asset impairment charges						62,000,000		787,000,000					768,000,000
Goodwill Impairment								$ 185,000,000
Asset impairment charge						66,000,000							787,000,000
Impairment									$ 299,000,000				299,000,000
2019 Restructuring Plan
Income Tax Contingency [Line Items]
Net restructuring and impairment costs												92,000,000
Tax charge (benefit) for restructuring												5,000,000
Restructuring and impairment costs												$ 105,000,000
2018 Restructuring Plan
Income Tax Contingency [Line Items]
Net restructuring and impairment costs													46,000,000
Tax charge (benefit) for restructuring													6,000,000
Restructuring and impairment costs													$ 71,000,000
2017 Restructuring Plan
Income Tax Contingency [Line Items]
Tax charge (benefit) for restructuring														7,000,000
Restructuring and impairment costs														$ 46,000,000
Futuris
Income Tax Contingency [Line Items]
Identifiable intangibles	$ 160,000,000
Useful life	10 years
Futuris | Customer relationships
Income Tax Contingency [Line Items]
Identifiable intangibles	$ 160,000,000
Useful life	10 years
GAAS
Income Tax Contingency [Line Items]
Income tax expense (benefit), adjustment							$ (7,000,000)
Tax rate							25.00%						15.00%
Identifiable intangibles		$ 276,000,000
Useful life		20 years
GAAS | Customer relationships
Income Tax Contingency [Line Items]
Identifiable intangibles		$ 276,000,000
Useful life		20 years
Foreign tax authority | Ireland
Income Tax Contingency [Line Items]
Statutory tax rate (as percent)												12.50%	12.50%	12.50%
Non-cash estimated tax expense												$ 503,000,000	$ 554,000,000	$ 21,000,000
Goodwill Impairment												0	(21,000,000)	0
Tax from nonconsolidated partially owned affiliates												$ 0	0	$ 19,000,000
Foreign tax authority | Canada
Income Tax Contingency [Line Items]
Deferred tax asset, increase (decrease) of valuation allowance													6,000,000
Foreign tax authority | Luxembourg
Income Tax Contingency [Line Items]
Income tax expense (benefit), adjustment					$ 229,000,000
Tax rate					17.00%					18.00%
Foreign tax authority | United Kingdom
Income Tax Contingency [Line Items]
Income tax expense (benefit), adjustment					$ 25,000,000
Foreign tax authority | Poland
Income Tax Contingency [Line Items]
Income tax expense (benefit), adjustment						$ 43,000,000
Deferred tax asset, increase (decrease) of valuation allowance													8,000,000
Foreign tax authority | Belgium
Income Tax Contingency [Line Items]
Deferred tax asset, increase (decrease) of valuation allowance													12,000,000
Foreign tax authority | Germany
Income Tax Contingency [Line Items]
Deferred tax asset, increase (decrease) of valuation allowance													175,000,000
Foreign tax authority | Hungary
Income Tax Contingency [Line Items]
Deferred tax asset, increase (decrease) of valuation allowance													14,000,000
Tax rate														9.00%
Tax expense														$ (5,000,000)
Foreign tax authority | Mexico
Income Tax Contingency [Line Items]
Deferred tax asset, increase (decrease) of valuation allowance													117,000,000
Foreign tax authority | Romania
Income Tax Contingency [Line Items]
Deferred tax asset, increase (decrease) of valuation allowance													9,000,000
United States
Income Tax Contingency [Line Items]
Deferred tax asset, increase (decrease) of valuation allowance													$ 281,000,000