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Derivatives and Other Financial Instruments - Schedule of Net Fair Values of Outstanding Derivative Contracts and Effect of Hypothetical Change (Increase or Decrease of 10%) in Market Prices or Rates (Detail) (USD $) In Millions, unless otherwise specified | Dec. 31, 2012
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Aluminum Contracts [Member] |
Derivative Instruments, Gain (Loss) [Line Items] |
Fair value asset/(liability) | $ (85)
Index change of + / - 10% | 111
Embedded Credit Derivative [Member] |
Derivative Instruments, Gain (Loss) [Line Items] |
Fair value asset/(liability) | (30)
Index change of + / - 10% | 3
Energy Contracts [Member] |
Derivative Instruments, Gain (Loss) [Line Items] |
Fair value asset/(liability) | 3
Index change of + / - 10% | 249
Foreign Exchange Contracts [Member] |
Derivative Instruments, Gain (Loss) [Line Items] |
Fair value asset/(liability) | 1
Index change of + / - 10% | 8
Interest Rate Contracts [Member] |
Derivative Instruments, Gain (Loss) [Line Items] |
Fair value asset/(liability) | 28
Index change of + / - 10% | $ 1

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- Definition Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 107 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 4, 17 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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