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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 | 12 Months Ended
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Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of gain or (loss) recognized in earnings related to ineffective portion of hedging relationships |  | $ (1) | $ 1
Aluminum Contracts [Member] | Sales [Member] |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Amount of gain or (loss) recognized in earnings related to ineffective portion of hedging relationships | $ (18) | $ 7 | $ (3)

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