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Acquisitions and Divestitures - Narrative (Detail) $ in Millions |  | 1 Months Ended | 3 Months Ended
--- | --- | --- | ---
Apr. 02, 2018 USD ($) | Mar. 31, 2017 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Mar. 31, 2017 USD ($) employee
Business Acquisition [Line Items] |  |  |  |  |
Third-party sale generated in last annual period prior to divestiture |  |  | $ 3,445 |  | $ 3,192
Restructuring and other charges |  |  | 7 |  | 73
Latin America Extrusions (LAE) | Disposal Group, Disposed of by Sale, Not Discontinued Operations |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Disposal group, including discontinued operation, revenue |  |  | $ 25 |  | 26
Latin America Extrusions (LAE) | Divested Businesses | Disposal Group, Disposed of by Sale, Not Discontinued Operations |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Restructuring and other charges |  |  |  | $ 41 |
Subsequent Event | Latin America Extrusions (LAE) | Disposal Group, Disposed of by Sale, Not Discontinued Operations |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Cash received on sale of operations | $ 5 |  |  |  |
Slim Aluminium |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Cash expense related to sale of rolling mill |  | $ 10 |  |  |
Third party guarantee with a fair value related to environmental remediation |  | $ 5 |  |  |
Disposal group, including discontinued operation, revenue |  |  |  |  | $ 37
Number of employees | employee |  |  |  |  | 312
Slim Aluminium | Restructuring and Other Charges |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |
Loss on sale of rolling mill |  |  |  |  | $ 60

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