XML 30 R43.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Fair value measurements (Details) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 9 Months Ended |  |  |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2013 Derivative Liabilities - Net [Member] | Sep. 30, 2012 Derivative Liabilities - Net [Member] | Sep. 30, 2013 Derivative Liabilities - Net [Member] | Sep. 30, 2012 Derivative Liabilities - Net [Member] | Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] | Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] | Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member] | Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member] | Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member] | Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member] | Sep. 30, 2013 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 3 [Member] | Dec. 31, 2012 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 3 [Member]
ASSETS: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash equivalents |  |  |  |  | $ 119,183 |  | $ 168,309 |  | $ 119,183 |  | $ 168,309 |  | $ 0 |  | $ 0 |  | $ 0 |  | $ 0 |
Trust assets (1) |  |  |  |  | 11,588 | [1] | 14,254 | [1] | 11,588 | [1] | 14,254 | [1] | 0 | [1] | 0 | [1] | 0 | [1] | 0 | [1]
Surety bonds |  |  |  |  | 1,574 |  | 2,123 |  | 1,574 |  | 2,123 |  | 0 |  | 0 |  | 0 |  | 0 |
Midwest premium contracts |  |  |  |  | 363 |  |  |  | 0 |  |  |  | 0 |  |  |  | 363 |  |  |
TOTAL |  |  |  |  | 132,708 |  | 184,686 |  | 132,345 |  | 184,686 |  | 0 |  | 0 |  | 363 |  | 0 |
LIABILITIES: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
E.ON contingent obligation – net (2) |  |  |  |  | 0 | [2] | 15,369 |  | 0 | [2] | 0 |  | 0 | [2] | 0 |  | 0 | [2] | 15,369 |
Primary aluminum sales contract |  |  |  |  | 771 |  | 1,170 |  | 0 |  | 0 |  | 0 |  | 0 |  | 771 |  | 1,170 |
TOTAL |  |  |  |  | 771 |  | 16,539 |  | 0 |  | 0 |  | 0 |  | 0 |  | 771 |  | 16,539 |
Level 3 fair value measurements [Roll Forward] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Beginning balance, January 1, | (773) | (16,024) | (16,539) | (14,760) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total gain (loss) included in earnings | 365 | (371) | 16,131 | (1,529) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Settlements | 0 | 0 | 0 | (106) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ending balance, September 30, | (408) | (16,395) | (408) | (16,395) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of gain (loss) included in earnings attributable to the change in unrealized losses relating to assets and liabilities held at September 30, | $ 365 | $ (371) | $ 16,131 | $ (1,529) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
[1] | Trust assets are currently invested in money market funds.
[2] | Based on the LME forward market prices for primary aluminum at September 30, 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 10 Debt for additional information about the E.ON contingent obligation fair value.

X
- Definition Fair values as of the balance sheet date of all primary aluminum sales contracts that meet the criteria of being accounted for as liability derivative instruments that do not qualify for normal purchases/normal sales exclusion. + References No definition available. + Details
Name: | cenx_PrimaryAluminumSalesContractsPremiumCollarFairValueDisclosure
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Fair values as of the balance sheet date of all surety bonds for workers compensation insurance as of the balance sheet date. + References No definition available. + Details
Name: | cenx_SuretyBondsWorkersCompInsuranceFairValueDisclosure
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value as of the balance sheet date of all trust assets as of the balance sheet date. + References No definition available. + Details
Name: | cenx_TrustAssetsFairValueDisclosure
Namespace Prefix: | cenx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
Name: | us-gaap_AssetsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash -URI http://asc.fasb.org/extlink&oid=6506951 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash Equivalents -URI http://asc.fasb.org/extlink&oid=6507016 + Details
Name: | us-gaap_CashAndCashEquivalentsFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: 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=28364263&loc=d3e13433-108611 Reference 2: 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 3: 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=28364263&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 5: 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 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226008-175313 + Details
Name: | us-gaap_DerivativeAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the amount of the total realized and unrealized gains or losses for the period which are included in the statement of income (or changes in net assets); the fair value of which assets and liabilities was or is measured on a recurring basis using significant unobservable inputs (Level 3). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisGainLossIncludedInEarnings
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Definition Fair value of obligations measured on a recurring basis. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueLiabilitiesMeasuredOnRecurringBasisObligations
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of purchases, (sales), issuances and (settlements) of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph c -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchasesSalesIssuancesSettlements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

X
- Definition Fair value of financial and nonfinancial obligations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
Name: | us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant