XML 45 R81.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Supplemental financial statement info Components of Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011
--- | --- | --- | --- | ---
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |
Other comprehensive loss before income tax effect | $ (129,913)us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1 |  | $ (105,891)us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1 |  |  |
Income tax effect (2) | 12,231 cenx_AccumulatedOtherComprehensiveIncomeTaxEffect | [1] | 14,059 cenx_AccumulatedOtherComprehensiveIncomeTaxEffect | [1] |  |
Accumulated other comprehensive loss | (117,682)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax |  | (91,832)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax |  | (151,192)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax | (134,588)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax
Defined benefit plan liabilities [Member] |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |
Other comprehensive loss before income tax effect | (128,664)us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1 / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |  | (92,177)us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1 / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |  |  |
Income tax effect (2) | 12,812 cenx_AccumulatedOtherComprehensiveIncomeTaxEffect / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |  | 14,256 cenx_AccumulatedOtherComprehensiveIncomeTaxEffect / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember |  |  |
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 |  | (137,441)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember | (124,948)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Equity in investee other comprehensive income [Member] |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |
Other comprehensive loss before income tax effect | 0 us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1 / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | [2] | (12,650)us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1 / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember | [2] |  |
Income tax effect (2) | 0 cenx_AccumulatedOtherComprehensiveIncomeTaxEffect / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember |  | 418 cenx_AccumulatedOtherComprehensiveIncomeTaxEffect / us-gaap_StatementEquityComponentsAxis = cenx_AccumulatedEquityInInvesteeAdjustmentMember |  |  |
Accumulated other comprehensive loss | 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
Unrealized loss on financial instruments [Member] |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |
Other comprehensive loss before income tax effect | (1,249)us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1 / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |  | (1,064)us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1 / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |  |  |
Income tax effect (2) | (581)cenx_AccumulatedOtherComprehensiveIncomeTaxEffect / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |  | (615)cenx_AccumulatedOtherComprehensiveIncomeTaxEffect / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember |  |  |
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 |  | $ (1,527)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember | $ (1,722)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax / us-gaap_StatementEquityComponentsAxis = us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
[1] | The allocation of the income tax effect to the components of other comprehensive income is as follows: 20142013Defined benefit plan liabilities$12,812$14,256Equity in investee other comprehensive income—418Unrealized loss on financial instruments(581)(615)
[2] | The amount includes our equity in the other comprehensive income of Mt. Holly until it was acquired.

X
- Definition The tax effect of AOCI as reported on the balance sheet. + References No definition available. + Details
Name: | cenx_AccumulatedOtherComprehensiveIncomeTaxEffect
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before tax of increase (decrease) in accumulated in equity from transactions and other events and circumstances from non-owner sources. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners (distributions to owners). + References No definition available. + Details
Name: | us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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
- 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: |