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Contingencies and Commitments - Additional Information - 2 (Detail) € in Millions, $ in Millions | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2017 USD ($) | Mar. 31, 2017 EUR (€) | Dec. 31, 2016 USD ($)
Loss Contingencies [Line Items] |  |  |
Total combined assessments | $ 265 | € 247 |
Guarantees of third party related to project financing | 45 |  |
Letters of credit, total amount committed | $ 107 |  |
Letters of credit, expiration date | 2017 |  |
Total amount committed under outstanding surety bonds | $ 121 |  |
Surety bonds, expiration date | 2017 |  |
Other Noncurrent Liabilities and Deferred Credits [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Combined fair value of guarantees | $ 35 |  | $ 35
Separation Agreement [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Guarantees of third party related to project financing | 330 |  |
Total amount committed under outstanding surety bonds | 22 |  |
Supply Agreement [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Guarantees of third party related to project financing | 1,600 |  |
Purchase Agreement [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Guarantees of third party related to project financing |  |  | $ 245
Alcoa Corporation Energy Supply Contracts Guarantee [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Guarantees of third party related to project financing | 50 |  |
Alcoa Corporation Environmental Liabilities Guarantee [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Guarantees of third party related to project financing | 53 |  |
Alcoa Corporation Workers Compensation Claims [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Letters of credit, total amount committed | 61 |  |
Alcoa Corporation Equipment Leases And Energy Contracts [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Letters of credit, total amount committed | $ 103 |  |
Minimum [Member] | Separation Agreement [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Guarantees, expiration date | 2017 |  |
Minimum [Member] | Outstanding bank guarantees [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Guarantees, expiration date | 2017 |  |
Maximum [Member] | Separation Agreement [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Guarantees, expiration date | 2024 |  |
Maximum [Member] | Outstanding bank guarantees [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Guarantees, expiration date | 2026 |  |

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- Definition The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248 + Details
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