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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 of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

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Long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets.

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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services 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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Percentage of fair value of reporting unit in excess of carrying amount.

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The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value.

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Properties, Plants, and Equipment, Net (Details) - USD ($)	3 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross			$ 11,806,000,000	$ 11,734,000,000
Less: accumulated depreciation and amortization			7,074,000,000	6,769,000,000
Properties plants and equipment excluding construction work in progress			4,732,000,000	4,965,000,000
Construction work-in-progress			731,000,000	739,000,000
Properties, plants, and equipment, net			5,463,000,000	5,704,000,000		$ 24,000,000
Non-cash asset impairments			$ 570,000,000	13,000,000	$ 58,000,000
Percentage of fair value in excess of carrying amount			50.00%
Land and land rights
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross			$ 128,000,000	136,000,000
Structures
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross			2,385,000,000	2,364,000,000
Machinery and equipment:
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross			9,293,000,000	9,234,000,000
Arconic Engines
Property, Plant and Equipment [Line Items]
Non-cash asset impairments	$ 428,000,000
Assets		$ 515,000,000
Percentage of fair value in excess of carrying amount		13.00%
Asset impairment charges		$ 0
Total segment sales \| Structures \| Engineered Products and Forgings
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross			812,000,000	769,000,000
Total segment sales \| Structures \| Global Rolled Products
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross			1,304,000,000	1,317,000,000
Total segment sales \| Machinery and equipment: \| Engineered Products and Forgings
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross			3,514,000,000	3,433,000,000
Total segment sales \| Machinery and equipment: \| Global Rolled Products
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross			5,401,000,000	5,356,000,000
Other
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, net			326,000,000	334,000,000
Other \| Structures
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross			269,000,000	278,000,000
Other \| Machinery and equipment:
Property, Plant and Equipment [Line Items]
Properties, plants, and equipment, gross			$ 378,000,000	$ 445,000,000
Property, Plant and Equipment \| Arconic Engines
Property, Plant and Equipment [Line Items]
Non-cash asset impairments	198,000,000
Indefinite-lived Intangible Assets
Property, Plant and Equipment [Line Items]
Non-cash asset impairments	197,000,000
Other Noncurrent Assets] \| Arconic Engines
Property, Plant and Equipment [Line Items]
Non-cash asset impairments	$ 33,000,000