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Derivatives And Other Financial Instruments - Additional Information (Detail) In Millions, unless otherwise specified | 9 Months Ended |  |  | 1 Months Ended | 9 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2012 USD ($) MetricTon | Jul. 30, 2012 USD ($) Contract | Dec. 31, 2009 USD ($) | Dec. 31, 2009 CAD | Jul. 30, 2012 Power Contract One [Member] | Jul. 30, 2012 Power Contract Two [Member] | Sep. 30, 2012 Six Year Natural Gas Supply Contract [Member] USD ($) | Sep. 30, 2012 Level 3 [Member] USD ($) | Sep. 30, 2012 Level 1 [Member] USD ($) | Dec. 31, 2011 Level 1 [Member] USD ($) | Sep. 30, 2012 Level 2 [Member] USD ($) | Dec. 31, 2011 Level 2 [Member] USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Net unrealized loss on derivative contracts |  |  |  |  |  |  | $ 5 | $ 102 |  |  |  |
Number of contract |  | 2 |  |  |  |  |  |  |  |  |  |
Power contract maturity date |  |  |  |  | Dec. 31, 2014 | Dec. 31, 2016 |  |  |  |  |  |
Derivative asset amount |  | 639 |  |  |  |  |  |  |  |  |  |
Supply contract duration |  |  |  |  |  |  | 6 years |  |  |  |  |
Amount of aluminum kmt designated as fair value hedges | 401 |  |  |  |  |  |  |  |  |  |  |
Face amount of debt the hedges effectively convert from fixed to floating through 2018 | 200 |  |  |  |  |  |  |  |  |  |  |
Contracts expiration date | September 2011 |  |  |  |  |  |  |  |  |  |  |
Forward contract to purchase to mitigate the foreign currency risk related to a Canadian-denominated loan due in 2014 |  |  | 59 | 58 |  |  |  |  |  |  |  |
Fair value hierarchy for public debt |  |  |  |  |  |  |  |  | (422) |  |  |
Fair value hierarchy for non-public debt |  |  |  |  |  |  |  |  |  |  | (118) |
Long-term debt, fair value |  |  |  |  |  |  |  |  | $ 8,638 | $ 8,576 | $ 615 | $ 698

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- Definition Aluminum futures designated as fair value hedges in kilo metric ton. + References No definition available. + Details
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- Definition Derivative instrument, obligation under contracts expiration date. + References No definition available. + Details
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- Definition Number Of Contracts + References No definition available. + Details
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- Definition The amount of foreign currency that the entity has contractually agreed, or for which it has the option, to buy or sell with respect to the contract being described. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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- Definition Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FIN39-1 -Paragraph 10A, 10B -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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611 Reference 4: 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. Reference 5: 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 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13495-108611 + Details
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- Definition This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c -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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- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
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