Net Property (Details) - USD ($) $ in Millions	Dec. 31, 2018	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Property at cost	$ 1,390	$ 1,382
Less: accumulated depreciation	(909)	(899)
Net property	481	483
Land and land improvements
Property, Plant and Equipment [Line Items]
Property at cost	29	29
Buildings
Property, Plant and Equipment [Line Items]
Property at cost	227	228
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property at cost	926	914
Company-owned tooling
Property, Plant and Equipment [Line Items]
Property at cost	132	130
Construction in progress
Property, Plant and Equipment [Line Items]
Property at cost	$ 76	$ 81

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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