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Derivatives and Other Financial Instruments - Schedule of Outstanding Forward Contracts that were Entered into Hedge Forecasted Transactions (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2013 t | Dec. 31, 2012 t
--- | --- | ---
Aluminum Contracts [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Aluminum contracts (000 metric tons) | 841,000 | 1,120,000
Energy Contracts [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Electricity (megawatt hours) | 59,409,328 | 100,578,295
Natural gas (million British thermal units) | 19,980,000 | 19,160,000
Foreign Exchange Contracts [Member] |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Foreign exchange contracts | $ 335 | $ 71

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- Definition Outstanding forward contracts entered into as hedge forecasted transactions, foreign exchange contracts. + References No definition available. + Details
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- Definition Outstanding forward contracts entered into as hedge forecasted transactions measured in British thermal units. + References No definition available. + Details
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- Definition Outstanding forward contracts entered into as hedge forecasted transactions measured in mega watt hours. + References No definition available. + Details
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- Definition Outstanding forward contracts entered into as hedging forecasted transactions measured in kilo metric ton. + References No definition available. + Details
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- Details
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