XML 69 R38.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Derivative and hedging instruments (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Mar. 31, 2013 | Mar. 31, 2013 Designated as Hedging Instrument [Member] | Dec. 31, 2012 Designated as Hedging Instrument [Member] | Mar. 31, 2013 E.ON Contingent Obligation [Member] Other Liabilities [Member] Designated as Hedging Instrument [Member] | Dec. 31, 2012 E.ON Contingent Obligation [Member] Other Liabilities [Member] Designated as Hedging Instrument [Member] | Mar. 31, 2013 Aluminum Sales Premium Contract [Member] Accrued and Other Current Liabilities [Member] Designated as Hedging Instrument [Member] | Dec. 31, 2012 Aluminum Sales Premium Contract [Member] Accrued and Other Current Liabilities [Member] Designated as Hedging Instrument [Member] | Mar. 31, 2013 Primary Aluminum Sales Contract Premium [Member] Not Designated as Hedging Instrument [Member] t | Dec. 31, 2012 Primary Aluminum Sales Contract Premium [Member] Not Designated as Hedging Instrument [Member] t
Fair value of derivative assets and liabilities by balance sheet location [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
DERIVATIVE LIABILITIES |  | $ 1,030 | $ 16,539 | $ 0 | [1] | $ 15,369 | [1] | $ 1,030 | $ 1,170 |  |  |  |
Outstanding forward contracts not designated as hedging instruments [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Aluminum forward contract outstanding (in metric tons) |  |  |  |  |  |  |  |  |  | 15,300 | [2] | 20,400 | [2]
Accumulated other comprehensive loss to be reclassified to earnings over the next 12-month period | $ 153 |  |  |  |  |  |  |  |  |  |  |  |
[1] | Based on the LME forward market prices for primary aluminum at March 31, 2013 and management's estimate of the LME forward market for periods beyond the quoted periods, we believe that we will not have any payment obligations for the E.ON contingent obligation through the term of the agreement which expires in 2028. See Note 9 Debt for additional information about the E.ON contingent obligation fair value.
[2] | Represents the remaining physical deliveries under the Glencore Metal Agreement.

X
- Definition The metric tons of aluminum covered by forward contracts outstanding for sales, put options and call options at the end of the period. + References No definition available. + Details
Name: | cenx_AluminumForwardContractsOutstanding
Namespace Prefix: | cenx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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

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

X
- Definition The estimated value of gains (losses), net anticipated to be transferred in the future from accumulated other comprehensive income into earnings. + References No definition available. + Details
Name: | us-gaap_DerivativeInstrumentsGainLossReclassificationFromAccumulatedOCIToIncomeEstimatedNetAmountToBeTransferred
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FIN39-1 -Paragraph 10A, 10B -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 Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 133 -Paragraph 4, 17 -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 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13495-108611 + Details
Name: | us-gaap_DerivativeLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant