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Derivatives And Other Financial Instruments (Schedule Of Reconciliation Of Activity For Derivative Contracts) (Details) (Level 3 [Member], USD $) In Millions, unless otherwise specified | 3 Months Ended
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Mar. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Ending balance | $ 704 |
Aluminum Contracts [Member] | Assets [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Beginning balance | 10 |
Sales - (decrease) | (3) |
Other income, net - (increase) | (1) |
Other comprehensive income - decrease (increase) | 2 |
Purchases, sales, issuances, and settlements |  | [1]
Transfers into and (or) out of Level 3 |  | [1]
Ending balance | 8 |
Aluminum Contracts [Member] | Liabilities [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Beginning balance | 602 |
Sales - (decrease) | (10) |
Other comprehensive income - decrease (increase) | 82 |
Purchases, sales, issuances, and settlements |  | [1]
Transfers into and (or) out of Level 3 |  | [1]
Ending balance | 674 |
Embedded Credit Derivative [Member] | Liabilities [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Beginning balance | 28 |
Purchases, sales, issuances, and settlements |  | [1]
Transfers into and (or) out of Level 3 |  | [1]
Ending balance | 28 |
Other income, net - (increase) | (1) |
Energy Contracts [Member] | Assets [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Beginning balance | 2 |
Other comprehensive income - decrease (increase) | (2) |
Purchases, sales, issuances, and settlements |  | [1]
Transfers into and (or) out of Level 3 |  | [1]
Energy Contracts [Member] | Liabilities [Member] |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] |  |
Other comprehensive income - decrease (increase) | 10 |
Purchases, sales, issuances, and settlements |  | [1]
Transfers into and (or) out of Level 3 |  | [1]
Ending balance | $ 10 |
[1] | There were no purchases, sales, issuances or settlements of Level 3 financial instruments. Additionally, there were no transfers of financial instruments into or out of Level 3.

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- Definition Fair Value Assets Measured On Recurring Basis Gain Loss Included In Other Expenses + References No definition available. + Details
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Balance Type: | debit
Period Type: | duration

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- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Other Expenses + References No definition available. + Details
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- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales Increase Decrease + References No definition available. + Details
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- Definition This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in other comprehensive income (a separate component of shareholders' equity). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c(1) -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 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258 + Details
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- Definition This element represents purchases, sales, issuances, and settlements (net) which have taken place during the period in relation to assets measured at fair value on a recurring basis using unobservable inputs (Level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c(2) -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 This element represents [net] transfers in to and out of assets measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 157 -Paragraph 32 -Subparagraph c(3) -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 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258 + 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 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. Reference 2: 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=6925170&loc=d3e19207-110258 + Details
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