XML 34 R45.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Commitments and contingencies (Details) (USD $) In Thousands, unless otherwise specified | 1 Months Ended | 3 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Nov. 30, 2011 | Jan. 31, 2010 | Mar. 31, 2012 Sites MW | Dec. 31, 2011 MW | Dec. 31, 2010 Plaintiffs | Apr. 30, 2010 LaborUnions | Jan. 02, 2010 | Nov. 30, 2009 Retirees | Dec. 31, 2006 SucceedingOwners
Environmental Contingencies [Abstract] |  |  |  |  |  |  |  |  |
Aggregate environmental-related accrued liabilities |  |  | $ 933 | $ 852 |  |  |  |  |
Number of sites in which interim remediation measures have been completed (in sites) |  |  | 2 |  |  |  |  |  |
Minimum amount expended by Company entitling them to reimbursement by third party for operating and maintaining water treatment system on behalf of third party |  |  | 400 |  |  |  |  |  |
Amount expended on hydrocarbon recovery plan under EPA Administrative Order |  |  | 940 |  |  |  |  |  |
Expected future potential payments under indemnification plan in order to comply with EPA Administrative Order |  |  | 500 |  |  |  |  |  |
Number of succeeding owners of alumina facility named as defendants in a lawsuit filed by the Commissioner of the Department of Planning and Natural Resources |  |  |  |  |  |  |  |  | 2
Number of plaintiffs to lawsuit alleging violations of territorial water pollution control laws in first lawsuit |  |  |  |  | 2,300 |  |  |  |
Number of plaintiffs to lawsuit alleging violations of territorial water pollution control laws in second lawsuit |  |  |  |  | 200 |  |  |  |
Damages sought for breach of contract and wrongful termination | $ 20,000 |  |  |  |  |  |  |  |
Ravenswood Retiree Medical Benefits [Abstract] |  |  |  |  |  |  |  |  |
Age at which retiree medical benefits will cease for retirees and dependents (age in years) |  | 65 years |  |  |  |  |  |  |
Age at which bargaining unit retirees and qualified dependents are covered by the salary retiree medical plan (age in years) |  | 65 years |  |  |  |  |  |  |
Number of retirees in part of class action lawsuit regarding Company's rights to modify or terminate retiree medical benefits |  |  |  |  |  |  | 4 | 4 |
Helguvik Agreement [Abstract] |  |  |  |  |  |  |  |  |
Power currently available under the power purchase agreement (in megawatts) |  |  |  | 47.5 |  |  |  |  |
Labor Commitments [Abstract] |  |  |  |  |  |  |  |  |
Percentage of U.S. based work force represented by a union (in hundredths) |  |  | 75.00% |  |  |  |  |  |
Number of labor unions foreign subsidiary entered into a new labor agreement with |  |  |  |  |  | 5 |  |  |
Percentage of foreign work force represented by the labor unions (in hundredths) |  |  |  |  |  | 84.00% |  |  |

X
- Definition Age Which Retiree Medical Benefits Will Cease for Retirees and Dependents + References No definition available. + Details
Name: | cenx_AgeWhichRetireeMedicalBenefitsWillCeaseForRetireesAndDependents
Namespace Prefix: | cenx_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | cenx_BigRiversAgreementAbstract
Namespace Prefix: | cenx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Eligibility Age for Coverage Under Medical Benefits Plan + References No definition available. + Details
Name: | cenx_EligibilityAgeForCoverageUnderMedicalBenefitsPlan
Namespace Prefix: | cenx_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The minimum amount of environmental remediation expenses that must occur before entitlement to third party reimbursement. + References No definition available. + Details
Name: | cenx_EnvironmentalRemediationExpenseMinimumAmountEntitlingReimbursementByThirdParty
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | cenx_LaborCommitmentsAbstract
Namespace Prefix: | cenx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of labor unions representing a group of employees. + References No definition available. + Details
Name: | cenx_NumberOfLaborUnionsUnderNewLaborAgreement
Namespace Prefix: | cenx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of plaintiffs subject to the 2010 potential lawsuit. + References No definition available. + Details
Name: | cenx_NumberOfPlaintiffs
Namespace Prefix: | cenx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of plaintiffs subject to the second potential lawsuit. + References No definition available. + Details
Name: | cenx_NumberOfPlaintiffsToSecondLawsuit
Namespace Prefix: | cenx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of former employees retired from a company. + References No definition available. + Details
Name: | cenx_NumberOfRetiredEmployeesIncludedInClassActionLawsuit
Namespace Prefix: | cenx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of sites with completed environmental remediation measures. + References No definition available. + Details
Name: | cenx_NumberOfSitesWithCompletedRemediationMeasures
Namespace Prefix: | cenx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of owners of an entity subsequent to the present owner. + References No definition available. + Details
Name: | cenx_NumberOfSuccessorOwners
Namespace Prefix: | cenx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The percentage of a Company's work force, based in the country of domicile, that are subject to collective bargaining agreements. + References No definition available. + Details
Name: | cenx_PercentageOfDomesticWorkForceInUnion
Namespace Prefix: | cenx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The percentage of a Company's Icelandic work force that are subject to collective bargaining agreements. + References No definition available. + Details
Name: | cenx_PercentageOfForeignWorkForceCoveredUnderNewLaborAgreement
Namespace Prefix: | cenx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The power currently available under the power purchase agreement. + References No definition available. + Details
Name: | cenx_PowerAvailable
Namespace Prefix: | cenx_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | cenx_RavenswoodRetireeMedicalBenefitsAbstract
Namespace Prefix: | cenx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total costs accrued as of the balance sheet date for environmental loss contingencies. + References Reference 1: 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 2: 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 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 96-1 -Paragraph 161 -Subparagraph a -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 5 -Paragraph 9 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 5: 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=6952336&loc=d3e14326-108349 + Details
Name: | us-gaap_AccrualForEnvironmentalLossContingencies
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Total anticipated costs associated with remediation, site restoration, postclosure, monitoring commitments, or other exit costs that may occur on the sale, disposal, or abandonment of a particular property resulting from unanticipated contamination of the assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 5 -Section Y -Paragraph Question 4 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 5.Y.Q4) -URI http://asc.fasb.org/extlink&oid=6572457&loc=d3e149879-122751 + Details
Name: | us-gaap_EnvironmentalExitCostsAnticipatedCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 96-1 -Paragraph 147, 148, 149, 150 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 143 -Paragraph 2 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number 90-8 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: 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=6943989&loc=d3e3602-108585 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 96-1 -Paragraph 170 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 5 -Paragraph 9, 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 7: 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 + Details
Name: | us-gaap_EnvironmentalRemediationExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Definition The value (monetary amount) of the award the plaintiff seeks in the legal matter. + References 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=6952336&loc=d3e14326-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 5 -Paragraph 9 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14557-108349 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 5 -Paragraph 11 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 5 -Paragraph 10 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 5 -Paragraph 12 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
Name: | us-gaap_LossContingencyDamagesSoughtValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration