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Derivatives And Other Financial Instruments (Narrative) (Details) | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Dec. 31, 2011 USD ($) MT | Dec. 31, 2010 USD ($) | Aug. 31, 2010 USD ($) | Dec. 31, 2009 USD ($) | Dec. 31, 2009 CAD | Dec. 31, 2011 Level 3 [Member] USD ($) | Dec. 31, 2010 Level 3 [Member] USD ($) | Dec. 31, 2011 Six-Year Natural Gas Supply Contract [Member] USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |  |  |  |  |  |  |
Net unrealized loss on derivative contracts |  |  |  |  |  | $ 618,000,000 | $ 779,000,000 | $ 5,000,000
Amount of aluminum kmt designated as fair value hedges | 419,000 |  |  |  |  |  |  |
Face amount of debt the hedges effectively convert from fixed to floating through 2018 | 515,000,000 |  |  |  |  |  |  |
Notional amount interest rate swaps | 550,000,000 | 825,000,000 | 825,000,000 |  |  |  |  |
Gain on termination of interest rate swaps | 33,000,000 | 28,000,000 |  |  |  |  |  |
Forward contract to purchase to mitigate the foreign currency risk related to a Canadian-denominated loan due in 2014 |  |  |  | $ 57,000,000 | 58,000,000 |  |  |

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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 + Details
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