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Property, Plant, and Equipment Property, Plant, and Equipment (Detail Textual) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property, plant and equipment — net	$ 1,291,218us-gaap_PropertyPlantAndEquipmentNet	$ 1,247,661us-gaap_PropertyPlantAndEquipmentNet
Construction in progress	182,393us-gaap_ConstructionInProgressGross	221,101us-gaap_ConstructionInProgressGross
Depreciation	70,731us-gaap_Depreciation	66,570us-gaap_Depreciation	62,570us-gaap_Depreciation
Mt. Holly Property, plant and equipment, gross		179,702cenx_EquityMethodInvestmentOwnershipInPropertyPlantAndEquipment
Mt. Holly Property Property, plant and equipment, accumulated depreciation		119,275cenx_EquityMethodInvestmentOwnershipInPropertyPlantAndEquipmentAccumulatedDepreciation
Ravenswood Aluminum Smelter [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment — net	45,683us-gaap_PropertyPlantAndEquipmentNet / us-gaap_PropertyPlantAndEquipmentByTypeAxis = cenx_RavenswoodAluminumSmelterMember
Helguvik Project [Member]
Property, Plant and Equipment [Line Items]
Construction in progress	$ 147,587us-gaap_ConstructionInProgressGross / us-gaap_PropertyPlantAndEquipmentByTypeAxis = cenx_HelguvikProjectMember

X

- Definition

Represents the entity's equity undivided ownership interest in property, plant and equipment in Mt. Holly partnership.

+ References

No definition available.

+ Details

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Namespace Prefix:	cenx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Represents the accumulated depreciation on entity's equity undivided ownership interest in property, plant and equipment in Mt. Holly partnership.

+ References

No definition available.

+ Details

Name:	cenx_EquityMethodInvestmentOwnershipInPropertyPlantAndEquipmentAccumulatedDepreciation
Namespace Prefix:	cenx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.13)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 13

-Subparagraph a

-Article 5



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 8

-Article 7

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	debit
Period Type:	instant

X

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=cenx_RavenswoodAluminumSmelterMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: