XML 108 R119.htm IDEA: XBRL DOCUMENT v2.4.1.9

Commitments and contingencies Legal Contingencies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended	45 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2016	Dec. 31, 2014
PBGC Agreement [Member]
Loss Contingencies [Line Items]
Pension Contributions	$ 6,700us-gaap_PensionContributions / us-gaap_LossContingenciesByNatureOfContingencyAxis = cenx_PBGCAgreementMember
Scenario, Forecast [Member] | PBGC Agreement [Member]
Loss Contingencies [Line Items]
Pension Contributions Above Required Minimum, Total		17,400cenx_PensionContributionsAboveRequiredMinimumTotal / us-gaap_LossContingenciesByNatureOfContingencyAxis = cenx_PBGCAgreementMember / us-gaap_StatementScenarioAxis = us-gaap_ScenarioForecastMember
Grundartangi Power Agreement [Member]
Loss Contingencies [Line Items]
Litigation Settlement, Amount			$ 3,600us-gaap_LitigationSettlementAmount / us-gaap_LitigationCaseAxis = cenx_GrundartangiPowerAgreementMember

X

- Definition

Pursuant to the terms of the settlement agreement with the Pension Benefit Guaranty Corporation, we will make additional contributions (above any minimum required contributions) to our defined benefit pension plans.

+ References

No definition available.

+ Details

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

X

- Definition

Amount of judgment or settlement awarded to (against) the entity in respect of litigation.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

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

X

- Definition

The amount of cash or cash equivalents contributed by the entity to fund its pension plans.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

+ Details

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

X

- Details

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

X

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=cenx_PBGCAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: