XML 148 R82.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Changes in components of Accumulated other comprehensive loss (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, Accumulated Other Comprehensive Loss | $ (117,682)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax |  |  |  |  |  |  |  | $ (91,832)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax |  |  |  |  |  |  |  | $ (117,682)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax | $ (91,832)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax | $ (151,192)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax | $ (134,588)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax
Other comprehensive income (loss) before reclassifications |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (43,345)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax | 56,787 us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax | (21,215)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax |
Net amount reclassified to net income (loss) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,844 us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax | 2,573 us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax | 4,611 us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax |
Elimination of equity in investee resulting from acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12,651 cenx_EliminationOfEquityInInvestee |  |  |
Cost of goods sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,728,586 us-gaap_CostOfGoodsSold | 1,414,790 us-gaap_CostOfGoodsSold | 1,225,769 us-gaap_CostOfGoodsSold |
Selling, general and administrative expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 49,195 us-gaap_SellingGeneralAndAdministrativeExpense | 67,477 us-gaap_SellingGeneralAndAdministrativeExpense | 35,363 us-gaap_SellingGeneralAndAdministrativeExpense |
Income tax expense |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 18,308 us-gaap_IncomeTaxExpenseBenefit | 3,131 us-gaap_IncomeTaxExpenseBenefit | 8,910 us-gaap_IncomeTaxExpenseBenefit |
Net income (loss) | 61,849 us-gaap_NetIncomeLoss | [1] | 50,405 us-gaap_NetIncomeLoss | [2] | 20,344 us-gaap_NetIncomeLoss | [3] | (20,104)us-gaap_NetIncomeLoss | [4] | (9,675)us-gaap_NetIncomeLoss | [5] | (9,507)us-gaap_NetIncomeLoss | [6] | (29,384)us-gaap_NetIncomeLoss | [7] | 8,253 us-gaap_NetIncomeLoss | [8] | 112,494 us-gaap_NetIncomeLoss | (40,313)us-gaap_NetIncomeLoss | (35,610)us-gaap_NetIncomeLoss |
Defined benefit plan liabilities [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, Accumulated Other Comprehensive Loss | (115,852)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |  |  |  |  |  |  |  | (77,921)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |  |  |  |  |  |  |  | (115,852)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (77,921)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (137,441)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (124,948)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Other comprehensive income (loss) before reclassifications |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (42,926)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 56,795 us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (16,691)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |
Net amount reclassified to net income (loss) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,995 us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 2,725 us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 4,198 us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |
Elimination of equity in investee resulting from acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 cenx_EliminationOfEquityInInvestee / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |  |  |
Equity in investee other comprehensive income [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, Accumulated Other Comprehensive Loss | 0 us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember |  |  |  |  |  |  |  | (12,232)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember |  |  |  |  |  |  |  | 0 us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | (12,232)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | (12,224)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | (7,918)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember
Other comprehensive income (loss) before reclassifications |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (419)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | (8)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | (4,306)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember |
Net amount reclassified to net income (loss) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | 0 us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | 0 us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember |
Elimination of equity in investee resulting from acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 12,651 cenx_EliminationOfEquityInInvestee / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember |  |  |
Unrealized loss on financial instruments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Balance, Accumulated Other Comprehensive Loss | (1,830)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |  |  |  |  |  |  |  | (1,679)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |  |  |  |  |  |  |  | (1,830)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (1,679)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (1,527)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (1,722)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Other comprehensive income (loss) before reclassifications |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 0 us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (218)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |
Net amount reclassified to net income (loss) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (151)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (152)us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 413 us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |
Elimination of equity in investee resulting from acquisition |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 cenx_EliminationOfEquityInInvestee / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |  |  |
Reclassification out of Accumulated Other Comprehensive Income [Member] | Defined benefit plan liabilities [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cost of goods sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 6,237 us-gaap_CostOfGoodsSold / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 3,264 us-gaap_CostOfGoodsSold / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 4,670 us-gaap_CostOfGoodsSold / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |
Selling, general and administrative expenses |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 569 us-gaap_SellingGeneralAndAdministrativeExpense / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 990 us-gaap_SellingGeneralAndAdministrativeExpense / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 1,055 us-gaap_SellingGeneralAndAdministrativeExpense / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |
Income tax expense |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (1,811)us-gaap_IncomeTaxExpenseBenefit / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (1,529)us-gaap_IncomeTaxExpenseBenefit / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (1,527)us-gaap_IncomeTaxExpenseBenefit / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |
Net income (loss) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4,995 us-gaap_NetIncomeLoss / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 2,725 us-gaap_NetIncomeLoss / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | 4,198 us-gaap_NetIncomeLoss / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |
Reclassification out of Accumulated Other Comprehensive Income [Member] | Equity in investee other comprehensive income [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cost of goods sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 us-gaap_CostOfGoodsSold / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | 0 us-gaap_CostOfGoodsSold / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | 0 us-gaap_CostOfGoodsSold / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember |
Income tax expense |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (419)us-gaap_IncomeTaxExpenseBenefit / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | (70)us-gaap_IncomeTaxExpenseBenefit / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | (70)us-gaap_IncomeTaxExpenseBenefit / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember |
Net income (loss) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (419)us-gaap_NetIncomeLoss / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | (70)us-gaap_NetIncomeLoss / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | (70)us-gaap_NetIncomeLoss / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember |
Reclassification out of Accumulated Other Comprehensive Income [Member] | Unrealized loss on financial instruments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cost of goods sold |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (185)us-gaap_CostOfGoodsSold / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | (186)us-gaap_CostOfGoodsSold / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 381 us-gaap_CostOfGoodsSold / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |
Income tax expense |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 34 us-gaap_IncomeTaxExpenseBenefit / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 34 us-gaap_IncomeTaxExpenseBenefit / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | 32 us-gaap_IncomeTaxExpenseBenefit / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |
Net income (loss) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (151)us-gaap_NetIncomeLoss / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | $ (152)us-gaap_NetIncomeLoss / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | $ 413 us-gaap_NetIncomeLoss / us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis = us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |
[1] | The fourth quarter of 2014 net income included a benefit of $7,943 for the gain on remeasurement of contingent consideration and a benefit of $1,318 for gain on remeasurement of our equity investment in Mt. Holly. Results were negatively impacted by $4,964 in non-cash, non-recurring pension charges and by $2,616 related to the separation of former senior executives.
[2] | The third quarter of 2014 net income reflects higher aluminum prices and lower power prices in the Midwestern U.S.
[3] | The second quarter of 2014 net income reflects higher aluminum prices and lower power prices in the Midwestern U.S. Results were negatively impacted by a charge of $500 for the finalization of a legal settlement.
[4] | The first quarter of 2014 cost of sales included a benefit of $5,534 related to deferred power contract liability amortization. Results were negatively impacted by a $3,100 charge for increased legal reserves.
[5] | The fourth quarter of 2013 cost of sales included a benefit of $16,570 related to deferred power contract liability amortization. During the quarter, inventory that had previously been written down to its market basis was consumed into cost of goods sold and inventory at the end of the quarter was written down to its market basis. The net impact of these valuation adjustments on costs of goods sold was a credit of $9,040. The financial results also include an $8,400 charge relating to the separation of our former CEO.
[6] | The third quarter of 2013 cost of sales included an $11,720 benefit for deferred power contract liability amortization. During the quarter, inventory that had previously been written down to its market basis was consumed into cost of goods sold and inventory at the end of the quarter was written down to its market basis. The net impact of these valuation adjustments on costs of goods sold was a credit of $5,762.
[7] | The second quarter of 2013 amounts differ from our reported second quarter results due to purchase price accounting adjustments related to the Sebree acquisition which were retroactively applied to the second quarter of 2013. The second quarter of 2013 net loss included a gain on bargain purchase of $5,253 and power contract amortization of $2,741 associated with the Sebree acquisition. Results were negatively impacted by a charge of $3,272 for the early extinguishment of our 8.0% Notes and a charge for severance and other expenses of $1,750 related to our corporate headquarters relocation. During the quarter, inventory that had previously been written down to its market basis was consumed into cost of goods sold and inventory at the end of the quarter was written down to its market basis. The net impact of these valuation adjustments on costs of goods sold was a charge of $10,211.
[8] | The first quarter of 2013 net income included a net benefit of $2,225 related to a litigation reserve adjustment and an unrealized gain of $15,722 related to a LME-based contingent obligation. Results were negatively impacted by severance and other expenses of $2,213 related to our corporate headquarters relocation. The net effect of reporting inventory on a lower of cost or market basis was a charge to cost of goods sold of $5,838 in the quarter.

X
- Definition Elimination of equity in investee as a result of the acquisition of the remaining interest in an equity method investment. + References No definition available. + Details
Name: | cenx_EliminationOfEquityInInvestee
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Definition Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e637-108580 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e681-108580 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669686-108580 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 31 -Article 5 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 + Details
Name: | us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Total costs related to goods produced and sold during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 2 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(a)) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
Name: | us-gaap_CostOfGoodsSold
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Article 4 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Income Tax Expense (or Benefit) -URI http://asc.fasb.org/extlink&oid=6515339 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319 + Details
Name: | us-gaap_IncomeTaxExpenseBenefit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. + References Reference 1: 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=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Other Comprehensive Income -URI http://asc.fasb.org/extlink&oid=6519514 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Net Income -URI http://asc.fasb.org/extlink&oid=6518256 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.19) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.18) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.22) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 19 -Article 5 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 20 -Article 9 + Details
Name: | us-gaap_NetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax, before reclassification adjustments of other comprehensive income (loss). + References No definition available. + Details
Name: | us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax of reclassification adjustments of other comprehensive income (loss). + References No definition available. + Details
Name: | us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.4) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 4 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 330 -SubTopic 10 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=34747878&loc=d3e3636-108311 + Details
Name: | us-gaap_SellingGeneralAndAdministrativeExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeAxis=us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=cenx_AccumulatedEquityInInvesteeAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |