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Contingencies And Commitments (Litigation) (Narrative) (Details) In Millions, unless otherwise specified |  |  | 0 Months Ended |  | 1 Months Ended | 12 Months Ended | 0 Months Ended |
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Mar. 31, 2012 USD ($) | Mar. 31, 2012 EUR (€) | Nov. 08, 2011 D | May 31, 2011 Negligence Award [Member] USD ($) | May 31, 2011 Breaches Of Warranty [Member] USD ($) | Nov. 30, 2006 Curtis v. Alcoa Inc. [Member] D employee | Dec. 31, 2011 St. Croix Renaissance Group, L.L.L.P. (SCRG), Brownfield Recovery Corp., And Energy Answers Corporation Of Puerto Rico [Member] USD ($) | Jan. 20, 2011 St. Croix Renaissance Group, L.L.L.P. (SCRG), Brownfield Recovery Corp., And Energy Answers Corporation Of Puerto Rico [Member] Breaches Of Warranty [Member] USD ($) | Jan. 20, 2011 St. Croix Renaissance Group, L.L.L.P. (SCRG), Brownfield Recovery Corp., And Energy Answers Corporation Of Puerto Rico [Member] Punitive Damages [Member] USD ($) | Jan. 20, 2011 St. Croix Renaissance Group, L.L.L.P. (SCRG), Brownfield Recovery Corp., And Energy Answers Corporation Of Puerto Rico [Member] Property Damages [Member] USD ($) | Feb. 27, 2008 Aluminium Bahrain B.S.C. (Alba) [Member] Y
Loss Contingencies [Line Items] |  |  |  |  |  |  |  |  |  |  |
Period of alleged conspiracy, years |  |  |  |  |  |  |  |  |  |  | 15
Number of days required to dismiss lawsuit |  |  | 30 |  |  |  |  |  |  |  |
Retired former employees involved in class action |  |  |  |  |  | 13,000 |  |  |  |  |
Trial length, number of days |  |  |  |  |  | 8 |  |  |  |  |
Management estimate for maximum exposure from class action | $ 115 | € 85 |  |  |  |  |  |  |  |  |
Damages awarded to plaintiff |  |  |  |  |  |  |  | 13 | 6 | 10 |
Post-trial litigation charge recorded |  |  |  |  |  |  | 20 |  |  |  |
Damages awarded to plaintiff, pre-judgment interest |  |  |  |  | 2 |  |  |  |  |  |
Court granted motion for judgment |  |  |  | $ 10 |  |  |  |  |  |  |

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- Definition Loss Contingency Damages Awarded Value. + References No definition available. + Details
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