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Business acquisitions Acquisition of Mt. Holly aluminum smelter additional (Details) (Mt. Holly Smelter [Member])	Dec. 01, 2014 t
Mt. Holly Smelter [Member]
Business Acquisition [Line Items]
Percentage of voting interests acquired (percentage)	50.30%us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeIncludingSubsequentAcquisitionPercentage / us-gaap_BusinessAcquisitionAxis = cenx_Mt.HollySmelterMember
Percentage of ownership after acquisition (percentage)	100.00%cenx_BusinessAcquisitionPercentageofOwnershipAfterAcquisition / us-gaap_BusinessAcquisitionAxis = cenx_Mt.HollySmelterMember
Employees	600dei_EntityNumberOfEmployees / us-gaap_BusinessAcquisitionAxis = cenx_Mt.HollySmelterMember
Primary aluminum capacity (in tonnes)	231,000cenx_Primaryaluminumcapacity / us-gaap_BusinessAcquisitionAxis = cenx_Mt.HollySmelterMember
Equity interest in acquiree (percentage)	49.70%us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireePercentage / us-gaap_BusinessAcquisitionAxis = cenx_Mt.HollySmelterMember

X

- Definition

Percentage of ownership at the acquisition date as a result of the business combination.

+ References

No definition available.

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X

- Definition

Annual production capacity of primary aluminum (in tonnes).

+ References

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- Definition

Number of persons employed by the Entity

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X

- Definition

Percentage of voting equity interests acquired in a business combination achieved in stages, including equity interests in the acquiree held by the acquirer immediately before the acquisition date and acquired at the acquisition date.

+ References

No definition available.

+ Details

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X

- Definition

Percentage of equity in the acquiree held by the acquirer immediately before the acquisition date in a business combination.

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No definition available.

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