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Acquisitions and Divestitures - 2017 Divestitures (Details) $ in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Mar. 31, 2017 USD ($) employee | Dec. 31, 2018 USD ($) | Sep. 30, 2018 USD ($) | Jun. 30, 2018 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Sep. 30, 2017 USD ($) | Jun. 30, 2017 USD ($) | Mar. 31, 2017 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($)
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Net loss on divestitures of businesses |  |  |  |  |  |  |  |  |  | $ (109) | $ 57 | $ 3
Sales |  | $ 3,472 | $ 3,524 | $ 3,573 | $ 3,445 | $ 3,271 | $ 3,236 | $ 3,261 | $ 3,192 | $ 14,014 | 12,960 | 12,394
Slim Aluminium |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Cash expense related to divestiture of business | $ 10 |  |  |  |  |  |  |  |  |  |  |
Guarantee payments to third party | $ 5 |  |  |  |  |  |  |  |  |  |  |
Sales |  |  |  |  |  |  |  |  |  |  | 54 | $ 165
Number of employees | employee | 312 |  |  |  |  |  |  |  |  |  |  |
Slim Aluminium | Restructuring and Other Charges |  |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Net loss on divestitures of businesses |  |  |  |  |  |  |  |  |  |  | $ 60 |

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