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Legal Contingencies [Abstract]

No definition available.

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

No definition available.

Name:	cenx_NumberOfLaborUnionsUnderNewLaborAgreement
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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Pursuant to the terms of the settlement agreement with the Pension Benefit Guaranty Corporation, this amount represents the remaining additional contributions (above any minimum required contributions) to our defined benefit pension plans.

No definition available.

Name:	cenx_PensionContributionsAboveRequiredMinimumRemaining
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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.

Name:	cenx_PensionContributionsAboveRequiredMinimumTotal
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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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Data Type:	num:percentItemType
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Period Type:	instant

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

No definition available.

Name:	cenx_PercentageOfForeignWorkForceCoveredUnderNewLaborAgreement
Namespace Prefix:	cenx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

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

No definition available.

Name:	cenx_PercentageofWorkForceinUnion
Namespace Prefix:	cenx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

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

No definition available.

Name:	cenx_PercentageofforeignNetherlandsworkforcerepresentedbythelaborunioninhundredths
Namespace Prefix:	cenx_
Data Type:	num:percentItemType
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The power currently available under the power purchase agreement.

No definition available.

Name:	cenx_PowerAvailable
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Balance Type:	na
Period Type:	instant

Power Supply Agreement, Termination Notice Period

No definition available.

Name:	cenx_PowerSupplyAgreementTerminationNoticePeriod
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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Short-term Agreement, Operating Capacity, Percentage

No definition available.

Name:	cenx_ShorttermAgreementOperatingCapacityPercentage
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Short-term Power Agreement, Number of Sources

No definition available.

Name:	cenx_ShorttermPowerAgreementNumberofSources
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Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Short-term Power Agreement, Supply from Source One, Percentage

No definition available.

Name:	cenx_ShorttermPowerAgreementSupplyfromSourceOnePercentage
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Short-term Power Agreement, Supply from Source Two, Percentage

No definition available.

Name:	cenx_ShorttermPowerAgreementSupplyfromSourceTwoPercentage
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Data Type:	num:percentItemType
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Short-term Power Agreement, Termination Notice Period

No definition available.

Name:	cenx_ShorttermPowerAgreementTerminationNoticePeriod
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Total costs accrued as of the balance sheet date for environmental loss contingencies.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346

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The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13296-110859

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

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- References

No definition available.

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The amount of cash or cash equivalents contributed by the entity to fund its pension plans.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3536-108585

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Data Type:	na
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