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Legal Contingencies [Abstract]

No definition available.

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Litigation Settlement, Amount Awarded to Other Party, Annual Payments

No definition available.

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Litigation Settlement Payment Period

No definition available.

Name:	cenx_LitigationSettlementPeriod
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The number of labor unions representing a group of employees.

No definition available.

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PBGC Settlement [Abstract]

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Pursuant to the terms of the settlement agreement with the Pension Benefit Guaranty Corporation, we will make additional contributions (above any minimum required contributions) to our defined benefit pension plans.

No definition available.

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Pension Contributions, Amended Term, Annual Contribution

No definition available.

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Pension Contributions, Amended Term, Total Contribution

No definition available.

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Pension Contributions, Term

No definition available.

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The percentage of a Company's work force, based in the country of domicile, that are subject to collective bargaining agreements.

No definition available.

Name:	cenx_PercentageOfDomesticWorkForceInUnion
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Percentage Of Foreign Netherlands Work Force Represented By The Labor Union

No definition available.

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The percentage of a Company's Icelandic work force that are subject to collective bargaining agreements.

No definition available.

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The percentage of a Company's work force that are subject to collective bargaining agreements.

No definition available.

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Power Supply Agreement, Increase Production At Full Capacity, Percentage

No definition available.

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Ravenswood litigation [Abstract]

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Short-term Power Agreement, Supply Percentage

No definition available.

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The power currently available under the power purchase agreement.

No definition available.

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Underlying, Derivative Power, Available, Extension

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Underlying, Derivative Power, Available, Requested

No definition available.

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Amount of gain (loss) recognized in settlement of litigation and insurance claims. Excludes claims within an insurance entity's normal claims settlement process.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

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Amount awarded to other party in judgment or settlement of litigation.

No definition available.

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Amount of loss contingency liability.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14615-108349

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The amount of cash paid for the settlement of litigation or for other legal issues during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (g)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3536-108585

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Amount of cash outflow for pension benefit. Includes, but is not limited to, employer contribution to fund plan asset and payment to retiree. Excludes other postretirement benefit.

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