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Other Income, Net - Additional Information (Detail) - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Feb. 28, 2017 | Dec. 31, 2017 | Jun. 30, 2017 | Dec. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Nov. 01, 2016
Other Non operating Income Expense [Line Items] |  |  |  |  |  |  |  |
Net loss (gain) from asset sales |  |  |  |  | $ 513 | $ 156 | $ 74 |
Pre-tax gain on sale of common stock |  |  | $ 167 |  | 167 |  |  |
Total amount committed under outstanding surety bonds |  | $ 54 |  |  | 54 |  |  |
Other, net |  |  |  |  | 103 | 79 | 18 |
Firth Rixson |  |  |  |  |  |  |  |
Other Non operating Income Expense [Line Items] |  |  |  |  |  |  |  |
Contingent consideration arrangements, change in amount of contingent consideration, liability |  | (81) |  | $ (56) | 81 | 56 |  |
Business combination, post acquisition closing adjustment |  |  |  |  |  | $ (20) |  |
Separation Agreement |  |  |  |  |  |  |  |
Other Non operating Income Expense [Line Items] |  |  |  |  |  |  |  |
Total amount committed under outstanding surety bonds |  | $ 25 |  |  | 25 |  |  | $ 25
Alcoa Corporation |  |  |  |  |  |  |  |
Other Non operating Income Expense [Line Items] |  |  |  |  |  |  |  |
Net loss (gain) from asset sales |  |  |  |  | $ 351 |  |  |
Pre-tax gain on sale of common stock | $ 351 |  |  |  |  |  |  |
Sherwin, TX Site |  |  |  |  |  |  |  |
Other Non operating Income Expense [Line Items] |  |  |  |  |  |  |  |
Net loss (gain) from asset sales |  |  |  |  |  |  | 19 |
China Rolling Mill Equity Investment |  |  |  |  |  |  |  |
Other Non operating Income Expense [Line Items] |  |  |  |  |  |  |  |
Net loss (gain) from asset sales |  |  |  |  |  |  | $ 19 |

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