| Component: (Network and Table) | |
|---|---|
| Network | 1122 - Disclosure - Income Taxes - Reconciliation of U.S. Federal Statutory Rate to Alcoa's Effective Tax Rate for Continuing Operations (Detail) (http://www.alcoa.com/taxonomy/role/DisclosureIncomeTaxesReconciliationOfUSFederalStatutoryRateToAlcoasEffectiveTaxRateForContinuingOperations) |
| Table | Reconciliation Of Effective Income Tax Rate [Table] |
| Reporting Entity [Axis] | 0000004281 (http://www.sec.gov/CIK) |
| Legal Entity [Axis] | Entity [Domain] |
| Income Taxes [Line Items] | Period [Axis] | ||
|---|---|---|---|
2012-01-01 - 2012-12-31 | 2011-01-01 - 2011-12-31 | 2010-01-01 - 2010-12-31 | |
U.S. federal statutory rate | 0.35 | 0.35 | 0.35 |
Taxes on foreign operations | (.001) | (.110) | (.054) |
Permanent differences on restructuring charges and asset disposals | .108 | .007 | |
Audit and other adjustments to prior years' accruals | .035 | (.011) | .012 |
Noncontrolling interests | .038 | .008 | .026 |
Statutory tax rate and law changes | (.004) | .008 | (.051) |
Tax law change related to Medicare Part D | .144 | ||
Changes in valuation allowances | .152 | .023 | (.087) |
Amortization of goodwill related to intercompany stock sales/reorganizations | (.077) | (.028) | (.052) |
Change in legal structure of investment | (.041) | ||
Interest income related to income tax positions | (.013) | (.002) | |
Company-owned life insurance/split-dollar net premiums | (.039) | (.002) | (.018) |
Other | (.008) | .004 | (.008) |
Effective tax rate | .500 | .240 | .269 |