XML 73 R52.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Business acquisitions - Acquisition of Sebree aluminum smelter (Details) $ / shares in Units, t in Thousands, $ in Thousands |  |  | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | ---
Dec. 01, 2014 USD ($) employee t | Jun. 01, 2013 USD ($) employee t | Jul. 31, 2014 USD ($) | Jun. 30, 2015 USD ($) | Mar. 31, 2015 USD ($) | Dec. 31, 2014 USD ($) | Jun. 30, 2014 USD ($) | Mar. 31, 2014 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($) $ / shares | Dec. 31, 2013 USD ($) $ / shares
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |
Purchase price |  |  |  |  |  |  |  |  | $ 0 | $ 1,042 | $ 48,058
Unrealized gain on fair value of contingent consideration |  |  |  |  | $ 6,527 | $ 7,943 |  |  | 18,337 | 7,943 | 0
Gain on bargain purchase |  |  |  |  |  |  |  |  | 0 | 0 | 5,253
Business Acquisition, Pro Forma Information [Abstract] |  |  |  |  |  |  |  |  |  |  |
Sebree power contract amortization |  |  |  |  |  |  |  | $ 5,534 | 0 | 5,534 | 31,031
Mt. Holly Smelter [Member] |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |
Primary aluminum capacity (in tonnes) | t | 231 |  |  |  |  |  |  |  |  |  |
Employees | employee | 600 |  |  |  |  |  |  |  |  |  |
Purchase price | $ 67,500 |  |  |  |  |  |  |  |  |  |
Purchase price | 67,500 |  |  |  |  |  |  |  |  |  |
Unrealized gain on fair value of contingent consideration |  |  |  | $ 10,287 |  |  |  |  | $ 18,337 |  |
Consideration: |  |  |  |  |  |  |  |  |  |  |
Total consideration | 67,767 |  |  |  |  |  |  |  |  |  |
Assets Acquired: |  |  |  |  |  |  |  |  |  |  |
Inventories | 23,979 |  |  |  |  |  |  |  |  |  |
Prepaid and other current assets | 2,527 |  |  |  |  |  |  |  |  |  |
Property, plant and equipment – net | 142,837 |  |  |  |  |  |  |  |  |  |
Total assets acquired | 214,034 |  |  |  |  |  |  |  |  |  |
Liabilities Assumed: |  |  |  |  |  |  |  |  |  |  |
Accrued and other current liabilities | 8,590 |  |  |  |  |  |  |  |  |  |
Accrued pension benefit costs | 34,595 |  |  |  |  |  |  |  |  |  |
Accrued postretirement benefit costs | 2,857 |  |  |  |  |  |  |  |  |  |
Other liabilities | 8,213 |  |  |  |  |  |  |  |  |  |
Deferred taxes | 2,686 |  |  |  |  |  |  |  |  |  |
Total liabilities assumed | $ 98,412 |  |  |  |  |  |  |  |  |  |
Business Acquisition, Pro Forma Information [Abstract] |  |  |  |  |  |  |  |  |  |  |
Sebree revenue |  |  |  |  |  |  |  |  |  | 25,911 |
Sebree income from continuing operations |  |  |  |  |  |  |  |  |  | 3,024 |
Pro forma revenues |  |  |  |  |  |  |  |  |  | 2,176,552 | 1,707,838
Pro forma loss from continuing operations |  |  |  |  |  |  |  |  |  | $ 125,847 | $ (38,819)
Pro forma loss per common share, basic (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  | $ 1.30 | $ (0.44)
Pro forma loss per common share, diluted (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  | $ 1.29 | $ (0.44)
Sebree Smelter [Member] |  |  |  |  |  |  |  |  |  |  |
Business Acquisition [Line Items] |  |  |  |  |  |  |  |  |  |  |
Primary aluminum capacity (in tonnes) | t |  | 218 |  |  |  |  |  |  |  |  |
Employees | employee |  | 500 |  |  |  |  |  |  |  |  |
Purchase price |  | $ 61,000 |  |  |  |  |  |  |  |  |
Purchase price |  |  | $ 49,035 |  |  |  |  |  |  |  |
Unrealized gain on fair value of contingent consideration |  |  |  |  |  |  | $ 965 |  |  |  |
Gain on bargain purchase |  | 5,253 |  |  |  |  |  |  |  |  | $ 5,253
Consideration: |  |  |  |  |  |  |  |  |  |  |
Total consideration |  | 48,083 |  |  |  |  |  |  |  |  |
Deferred purchase price |  | 1,910 |  |  |  |  |  |  |  |  |
Assets Acquired: |  |  |  |  |  |  |  |  |  |  |
Inventories |  | 59,018 |  |  |  |  |  |  |  |  |
Prepaid and other current assets |  | 2,273 |  |  |  |  |  |  |  |  |
Property, plant and equipment – net |  | 55,520 |  |  |  |  |  |  |  |  |
Total assets acquired |  | 116,811 |  |  |  |  |  |  |  |  |
Liabilities Assumed: |  |  |  |  |  |  |  |  |  |  |
Accrued and other current liabilities |  | 43,316 |  |  |  |  |  |  |  |  |
Accrued pension benefit costs |  | 996 |  |  |  |  |  |  |  |  |
Accrued postretirement benefit costs |  | 6,544 |  |  |  |  |  |  |  |  |
Other liabilities |  | 7,476 |  |  |  |  |  |  |  |  |
Deferred taxes |  | 3,233 |  |  |  |  |  |  |  |  |
Total liabilities assumed |  | $ 61,565 |  |  |  |  |  |  |  |  |
Business Acquisition, Pro Forma Information [Abstract] |  |  |  |  |  |  |  |  |  |  |
Sebree revenue |  |  |  |  |  |  |  |  |  |  | 247,178
Sebree income from continuing operations |  |  |  |  |  |  |  |  |  |  | 8,705
Sebree power contract amortization |  |  |  |  |  |  |  |  |  | $ 5,534 | 31,031
Pro forma revenues |  |  |  |  |  |  |  |  |  |  | 1,662,707
Pro forma loss from continuing operations |  |  |  |  |  |  |  |  |  |  | $ (83,035)
Pro forma loss per common share, basic (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ (0.94)
Pro forma loss per common share, diluted (in dollars per share) | $ / shares |  |  |  |  |  |  |  |  |  |  | $ (0.94)

X
- Definition The aggregate benefit recognized in earnings to allocate the assumed power contract liability in a systematic and rational manner over the contract period. As a noncash benefit, this element is subtracted from net income when calculating cash provided by or used in operations using the indirect method. + References No definition available. + Details
Name: | cenx_AmortizationofAssumedPowerContract
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This amount represents the purchase price of the business acquisition. + References No definition available. + Details
Name: | cenx_BusinessAcquisitionPurchasePrice
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition This amount represents deferred purchase price as a result of certain working capital adjustments due to the previous owner. + References No definition available. + Details
Name: | cenx_BusinessCombinationDeferredPurchasePrice
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of acquisition cost of a business combination allocated to pension benefit costs of the acquired entity. + References No definition available. + Details
Name: | cenx_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedPensionBenefitCosts
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of acquisition cost of a business combination allocated to post retirement benefits of the acquired entity. + References No definition available. + Details
Name: | cenx_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedPostRetirementBenefits
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Annual production capacity of primary aluminum (in tonnes). + References No definition available. + Details
Name: | cenx_Primaryaluminumcapacity
Namespace Prefix: | cenx_
Data Type: | num:massItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of persons employed by the Entity + References No definition available. + Details
Name: | dei_EntityNumberOfEmployees
Namespace Prefix: | dei_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_BusinessAcquisitionLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The pro forma income from continuing operations before changes in accounting and extraordinary items, net of tax effect per basic share of common stock for a period as if the business combination or combinations had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareBasic
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition The pro forma income from continuing operations before changes in accounting and extraordinary items, net of tax effect, per diluted share of common stock for a period as if the business combination or combinations had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTaxPerShareDiluted
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_BusinessAcquisitionProFormaInformationAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The pro forma income from continuing operations before changes in accounting and extraordinary items, net of tax effect, for the period as if the business combination or combinations had been completed at the beginning of a period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionsProFormaIncomeLossFromContinuingOperationsBeforeChangesInAccountingAndExtraordinaryItemsNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)-(3) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessAcquisitionsProFormaRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition In a business combination in which the amount of net identifiable assets acquired and liabilities assumed exceeds the aggregate consideration transferred or to be transferred (as defined), this element represents the amount of gain recognized by the entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 25 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6393-128476 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6527-128477 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (f)(1) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6571-128477 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 25 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6387-128476 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 25 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6396-128476 + Details
Name: | us-gaap_BusinessCombinationBargainPurchaseGainRecognizedAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477 + Details
Name: | us-gaap_BusinessCombinationConsiderationTransferred1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_BusinessCombinationConsiderationTransferredAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition This element represents the amount of earnings or loss of the acquiree since the acquisition date included in the consolidated income statement for the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessCombinationProFormaInformationEarningsOrLossOfAcquireeSinceAcquisitionDateActual
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActual
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of assets acquired at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer, acquired at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of other liabilities due within one year or within the normal operating cycle, if longer, assumed at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of deferred tax liability attributable to taxable temporary differences due after one year or the normal operating cycle, if longer, assumed at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilitiesNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of inventory recognized as of the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 55 -Paragraph 37 -URI http://asc.fasb.org/extlink&oid=35744172&loc=d3e2207-128464 + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of liabilities assumed at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilitiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of other liabilities due after one year or the normal operating cycle, if longer, assumed at the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount of property, plant, and equipment recognized as of the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 55 -Paragraph 37 -URI http://asc.fasb.org/extlink&oid=35744172&loc=d3e2207-128464 + Details
Name: | us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The revenues and gains recognized recorded for each transaction with the acquiree that is recognized separately from the acquisition of assets and assumptions of liabilities in the business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e)(3) -URI http://asc.fasb.org/extlink&oid=56956515&loc=d3e1392-128463 + Details
Name: | us-gaap_BusinessCombinationSeparatelyRecognizedTransactionsRevenuesAndGainsRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Investing Activities -URI http://asc.fasb.org/extlink&oid=6516133 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 13 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3213-108585 + Details
Name: | us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=cenx_Mt.HollySmelterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=cenx_SebreeSmelterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |