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Pension and Other Postretirement Benefits Discount Rate Change in Estimate (Details) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
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Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items] |
Basis point change to discount rate (in basis points) | 25 cenx_Basispointchangetodiscountrate
Pension Obligation due to change in discount rate | $ 10,000 cenx_PensionObligationDueToChangeInDiscountRate

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- Definition Basis point change to pension plan assumption discount rate used in calculating the net periodic cost. + References No definition available. + Details
Name: | cenx_Basispointchangetodiscountrate
Namespace Prefix: | cenx_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | duration

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- Definition Pension Obligation due to change in discount rate in pension plan assumption used in calculating the net periodic cost + References No definition available. + Details
Name: | cenx_PensionObligationDueToChangeInDiscountRate
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration