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Derivatives and Other Financial Instruments - Schedule of Gain or Loss on Hedged Items and Derivative Contracts (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended
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Mar. 31, 2013 | Mar. 31, 2012
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of gain recognized in earnings related to the ineffective portion of hedging relationships | $ 1 | $ 9
Aluminum contracts [Member] | Sales [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Amount of gain recognized in earnings related to the ineffective portion of hedging relationships | $ 12 |

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- Details
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