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Commitments and contingencies Legal Contingencies (Details) (USD $) In Thousands, unless otherwise specified | 12 Months Ended | 45 Months Ended | 12 Months Ended
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Dec. 31, 2013 | Dec. 31, 2016 | Dec. 31, 2014
PBGC Agreement [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Pension Contributions | $ 6,700 us-gaap_PensionContributions / us-gaap_LossContingenciesByNatureOfContingencyAxis = cenx_PBGCAgreementMember |  |
Scenario, Forecast [Member] | PBGC Agreement [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Pension Contributions Above Required Minimum, Total |  | 17,400 cenx_PensionContributionsAboveRequiredMinimumTotal / us-gaap_LossContingenciesByNatureOfContingencyAxis = cenx_PBGCAgreementMember / us-gaap_StatementScenarioAxis = us-gaap_ScenarioForecastMember |
Grundartangi Power Agreement [Member] |  |  |
Loss Contingencies [Line Items] |  |  |
Litigation Settlement, Amount |  |  | $ 3,600 us-gaap_LitigationSettlementAmount / us-gaap_LitigationCaseAxis = cenx_GrundartangiPowerAgreementMember

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- Definition 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. + References No definition available. + Details
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- Definition Amount of judgment or settlement awarded to (against) the entity in respect of litigation. + References No definition available. + Details
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- Details
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- Definition The amount of cash or cash equivalents contributed by the entity to fund its pension plans. + References 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=31042434&loc=d3e3536-108585 + Details
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- Details
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- Details
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