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Pension And Other Postretirement Benefits (Schedule Of Fair Value Of Pension And Postretirement Plans' Assets) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2011 | Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | $ 10,339 | [1] | $ 9,486 | [1]
Net payable which represents securities purchased not yet settled less interest and dividends earned on various investments | 20 |  | 23 |
Level 1 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 2,459 | [1] | 2,424 | [1]
Level 2 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 5,120 | [1] | 5,563 | [1]
Level 3 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 2,760 | [1] | 1,499 | [1]
Other Investments [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 1,535 |  | 1,128 |
Other Investments [Member] | Level 1 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 295 |  | 268 |
Other Investments [Member] | Level 2 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 74 |  | 52 |
Other Investments [Member] | Level 3 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 1,166 |  | 808 |
Equity Securities [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 3,490 | [2] | 3,441 |
Equity Securities [Member] | Level 1 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 941 | [2] | 1,348 |
Common stock related to plan contribution | 36 |  |  |
Equity Securities [Member] | Level 2 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 1,166 | [2] | 1,589 |
Equity Securities [Member] | Level 3 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 1,383 | [2] | 504 |
Debt Securities [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 5,314 |  | 4,917 |
Debt Securities [Member] | Level 1 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 1,223 |  | 808 |
Debt Securities [Member] | Level 2 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | 3,880 |  | 3,922 |
Debt Securities [Member] | Level 3 [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Fair value of pension and other postretirement plans' assets | $ 211 |  | $ 187 |
[1] | As of December 31, 2011, the total fair value of pension and other postretirement plans' assets excludes a net payable of $20, which represents securities purchased not yet settled less interest and dividends earned on various investments. As of December 31, 2010, the total fair value of pension and other postretirement plans' assets excludes a net receivable of $23, which represents interest and dividends earned on various investments less securities purchased not yet settled.
[2] | At December 31, 2011, Level 1 equity securities include $36 of Alcoa common stock related to the January 2011 plan contribution (see Funding and Cash Flows section below).

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- Definition Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=6867990&loc=d3e12355-114930 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph d(iv)(b)(i) -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 Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph b -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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 49 -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 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920 + Details
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