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Debt (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015		Dec. 31, 2014
Schedule of Debt Instruments [Line Items]
Industrial revenue bonds	$ 7,815cenx_IndustrialRevenueBonds		$ 7,815cenx_IndustrialRevenueBonds
TOTAL	254,798us-gaap_DebtLongtermAndShorttermCombinedAmount		254,703us-gaap_DebtLongtermAndShorttermCombinedAmount
Industrial revenue bonds due 2028 [Member] | Short-term Debt [Member]
Schedule of Debt Instruments [Line Items]
Debt Instrument, Unamortized Discount	0us-gaap_DebtInstrumentUnamortizedDiscount / us-gaap_DebtInstrumentAxis = cenx_IndustrialRevenueBondsDue2028Member / us-gaap_ShortTermDebtTypeAxis = us-gaap_ShortTermDebtMember	[1]	0us-gaap_DebtInstrumentUnamortizedDiscount / us-gaap_DebtInstrumentAxis = cenx_IndustrialRevenueBondsDue2028Member / us-gaap_ShortTermDebtTypeAxis = us-gaap_ShortTermDebtMember	[1]
Debt Instrument, Maturity Date	Apr. 01, 2028	[1]	Apr. 01, 2028	[1]
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Maximum	12.00%us-gaap_DebtInstrumentInterestRateEffectivePercentageRateRangeMaximum / us-gaap_DebtInstrumentAxis = cenx_IndustrialRevenueBondsDue2028Member / us-gaap_ShortTermDebtTypeAxis = us-gaap_ShortTermDebtMember	[1]	12.00%us-gaap_DebtInstrumentInterestRateEffectivePercentageRateRangeMaximum / us-gaap_DebtInstrumentAxis = cenx_IndustrialRevenueBondsDue2028Member / us-gaap_ShortTermDebtTypeAxis = us-gaap_ShortTermDebtMember	[1]
Industrial revenue bonds	7,815cenx_IndustrialRevenueBonds / us-gaap_DebtInstrumentAxis = cenx_IndustrialRevenueBondsDue2028Member / us-gaap_ShortTermDebtTypeAxis = us-gaap_ShortTermDebtMember	[1]	7,815cenx_IndustrialRevenueBonds / us-gaap_DebtInstrumentAxis = cenx_IndustrialRevenueBondsDue2028Member / us-gaap_ShortTermDebtTypeAxis = us-gaap_ShortTermDebtMember	[1]
Debt Instrument, Interest Rate, Stated Percentage	0.22%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = cenx_IndustrialRevenueBondsDue2028Member / us-gaap_ShortTermDebtTypeAxis = us-gaap_ShortTermDebtMember
Senior secured notes due June 01, 2021 [Member] | Long-term Debt [Member]
Schedule of Debt Instruments [Line Items]
Debt Instrument, Unamortized Discount	3,017us-gaap_DebtInstrumentUnamortizedDiscount / us-gaap_DebtInstrumentAxis = cenx_SeniorsecurednotesdueJune012021Member / us-gaap_LongtermDebtTypeAxis = us-gaap_LongTermDebtMember		3,112us-gaap_DebtInstrumentUnamortizedDiscount / us-gaap_DebtInstrumentAxis = cenx_SeniorsecurednotesdueJune012021Member / us-gaap_LongtermDebtTypeAxis = us-gaap_LongTermDebtMember
Debt Instrument, Maturity Date	Jun. 01, 2021		Jun. 01, 2021
Senior secured notes, noncurrent	$ 246,983us-gaap_SecuredLongTermDebt / us-gaap_DebtInstrumentAxis = cenx_SeniorsecurednotesdueJune012021Member / us-gaap_LongtermDebtTypeAxis = us-gaap_LongTermDebtMember		$ 246,888us-gaap_SecuredLongTermDebt / us-gaap_DebtInstrumentAxis = cenx_SeniorsecurednotesdueJune012021Member / us-gaap_LongtermDebtTypeAxis = us-gaap_LongTermDebtMember
Debt Instrument, Interest Rate, Stated Percentage	7.50%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = cenx_SeniorsecurednotesdueJune012021Member / us-gaap_LongtermDebtTypeAxis = us-gaap_LongTermDebtMember		7.50%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_DebtInstrumentAxis = cenx_SeniorsecurednotesdueJune012021Member / us-gaap_LongtermDebtTypeAxis = us-gaap_LongTermDebtMember
[1] The IRBs are classified as current liabilities because they are remarketed weekly and could be required to be repaid upon demand if there is a failed remarketing. The IRB interest rate at March 31, 2015 was 0.22%.

X

- Definition

Carrying value as of the balance sheet date of the long-term debt associated with industrial revenue bonds. For classified balance sheets, these bonds are considered current assets because they are remarketed weekly and the bonds could be required to be repaid upon demand if there is a failed remarketing.

+ References

No definition available.

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- Definition

When presenting a range of interest rates, the highest effective rate for funds borrowed under the debt agreement as of the balance sheet date.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Represents the aggregate of total long-term debt, including current maturities and short-term debt.

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- Definition

Carrying amount of collateralized debt obligations with maturities initially due after one year or beyond the operating cycle, if longer, excluding the current portion. Obligations include, but not limited to, mortgage loans, chattel loans, and other borrowings secured by assets.

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