Name:	cenx_LaborCommitmentsAbstract
Namespace Prefix:	cenx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Legal Contingencies [Abstract]

No definition available.

Name:	cenx_LegalContingenciesAbstract
Namespace Prefix:	cenx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Litigation Settlement, Annual Installment

No definition available.

Name:	cenx_LitigationSettlementAnnualInstallment
Namespace Prefix:	cenx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Litigation Settlement, Payable upon Final Approval of Settlement

No definition available.

Name:	cenx_LitigationSettlementPayableuponFinalApprovalofSettlement
Namespace Prefix:	cenx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The number of labor unions representing a group of employees.

No definition available.

Name:	cenx_NumberOfLaborUnionsUnderNewLaborAgreement
Namespace Prefix:	cenx_
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
Namespace Prefix:	cenx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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
Namespace Prefix:	cenx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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

The power currently available under the power purchase agreement.

No definition available.

Name:	cenx_PowerAvailable
Namespace Prefix:	cenx_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

Power Supply Agreement, Termination Notice Period

No definition available.

Name:	cenx_PowerSupplyAgreementTerminationNoticePeriod
Namespace Prefix:	cenx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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

No definition available.

Name:	cenx_ShorttermPowerAgreementSupplyfromSourceOnePercentage
Namespace Prefix:	cenx_
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
Namespace Prefix:	cenx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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

Name:	us-gaap_AccrualForEnvironmentalLossContingencies
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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=66902209&loc=d3e3602-108585

Name:	us-gaap_EnvironmentalRemediationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

Name:	us-gaap_EnvironmentalRemediationObligationsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Aggregate carrying amount of the estimated litigation liability for known or estimated probable loss from litigation, which may include attorneys' fees and other litigation costs.

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 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.25)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_LitigationReserve
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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=66902209&loc=d3e3536-108585

Name:	us-gaap_PensionContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Name:	us-gaap_CounterpartyNameAxis=cenx_PBGCAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CounterpartyNameAxis=cenx_HawesvilleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CounterpartyNameAxis=cenx_SebreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CounterpartyNameAxis=cenx_SouthCarolinaPublicServiceAuthorityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CounterpartyNameAxis=cenx_GrundartangiHSLandsvirkjunandORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CounterpartyNameAxis=cenx_GrundartangiLandsvirkjunMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CounterpartyNameAxis=cenx_HelguvikMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: