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Forward delivery contracts and financial instruments (Details) - t | 6 Months Ended |
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Jun. 30, 2015 | Dec. 31, 2014
Primary Aluminum Sales Contracts [Member] | Glencore Nordural Metal Agreement [Member] |  |  |
Supply Commitment [Line Items] |  |  |
Customer | [1] | Glencore |
Volume | [1] | All primary aluminum produced at Grundartangi, net of tolling and other sales commitments |
Volume (in tonnes) |  | 205,000 |
Term | [1] | January 1, 2014 through December 31, 2017 |
Pricing | [1] | Variable, based on LME and European Duty Paid premium |
Primary Aluminum Sales Contracts [Member] | Glencore U.S. Aluminum Sales Agreement [Member] |  |  |
Supply Commitment [Line Items] |  |  |
Customer |  | Glencore |
Volume |  | Substantially all of the primary aluminum produced in North America |
Term |  | January 1, 2015 through December 31, 2016 |
Pricing |  | Variable, based on LME and Midwest premium and product premiums, as applicable |
Long-Term Tolling Conctracts [Member] | Glencore Toll Agreement 1 [Member] |  |  |
Supply Commitment [Line Items] |  |  |
Customer |  | Glencore |
Volume |  | 90,000 tonnes per year ("tpy") |
Volume (in tonnes) |  | 90,000 |
Term |  | Through July 2016 |
Pricing |  | Variable, based on LME and European Duty Paid premium |
Other Forward Delivery Contracts [Member] |  |  |
Supply Commitment [Line Items] |  |  |
Other forward delivery contracts to sell primary aluminum (in tonnes) |  | 3,033 | 6,108
Glencore [Member] | Other Forward Delivery Contracts [Member] |  |  |
Supply Commitment [Line Items] |  |  |
Other forward delivery contracts to sell primary aluminum (in tonnes) |  | 0 | 4,058
[1] | The Glencore Grundartangi Metal Agreement is for all metal produced at Grundartangi from 2014 through 2017, less commitments under existing tolling and other sales contracts. Grundartangi currently estimates that it will sell Glencore approximately 205,000 tonnes of aluminum under this agreement in 2015.

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- Definition Annual Primary Aluminum Physical Delivery Contract (Maximum) + References No definition available. + Details
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- Definition Long Term Contract For Purchase Of Primary Aluminum, Contract Expiration Date + References No definition available. + Details
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Namespace Prefix: | cenx_
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- Definition The description of the pricing terms for long term sales contracts. + References No definition available. + Details
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Balance Type: | na
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- Definition The name of a particular customer for a company. + References No definition available. + Details
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Balance Type: | na
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- Definition Total amount of primary aluminum committed to be supplied under existing contracts or agreements outside of major long-term supply commitments. + References No definition available. + Details
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- Definition Description of the particular sales volume for a particular customer. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Details
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- Details
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- Details
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- Details
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