Litigation Settlement, Annual Installment

No definition available.

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

- Definition

Litigation Settlement Installment Period

+ References

No definition available.

+ Details

Name:	cenx_LitigationSettlementInstallmentPeriod
Namespace Prefix:	cenx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Litigation Settlement Payment Period

+ References

No definition available.

+ Details

Name:	cenx_LitigationSettlementPeriod
Namespace Prefix:	cenx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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

- Definition

Pension Contributions, Amended Term, Annual Contribution

+ References

No definition available.

+ Details

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

- Definition

Pension Contributions, Amended Term, Total Contribution

+ References

No definition available.

+ Details

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

- Definition

Pension Contributions, Term

+ References

No definition available.

+ Details

Name:	cenx_PensionContributionsTerm
Namespace Prefix:	cenx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Power Supply Agreement, Increase Production At Full Capacity, Percentage

+ References

No definition available.

+ Details

Name:	cenx_PowerSupplyAgreementIncreaseProductionAtFullCapacityPercentage
Namespace Prefix:	cenx_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Short-term Power Agreement, Supply Percentage

+ References

No definition available.

+ Details

Name:	cenx_ShortTermPowerAgreementSupplyPercentage
Namespace Prefix:	cenx_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The power currently available under the power purchase agreement.

+ References

No definition available.

+ Details

Name:	cenx_UnderlyingDerivativePowerAvailable
Namespace Prefix:	cenx_
Data Type:	dtr-types:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

Underlying, Derivative Power, Available, Extension

+ References

No definition available.

+ Details

Name:	cenx_UnderlyingDerivativePowerAvailableExtension
Namespace Prefix:	cenx_
Data Type:	dtr-types:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

Underlying, Derivative Power, Available, Requested

+ References

No definition available.

+ Details

Name:	cenx_UnderlyingDerivativePowerAvailableRequested
Namespace Prefix:	cenx_
Data Type:	dtr-types:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

Underlying, Derivative Power, Rate

+ References

No definition available.

+ Details

Name:	cenx_UnderlyingDerivativePowerRate
Namespace Prefix:	cenx_
Data Type:	dtr-types:powerItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of gain (loss) recognized in settlement of litigation and insurance claims. Excludes claims within an insurance entity's normal claims settlement process.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

+ Details

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

- Definition

Amount awarded to other party in judgment or settlement of litigation.

+ References

No definition available.

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=121557415&loc=d3e14615-108349

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of loss contingency liability expected to be resolved within one year or the normal operating cycle, if longer.

+ References

+ Details

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

- Definition

Amount of liabilities classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15)
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

+ Details

Name:	us-gaap_OtherLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of cash paid for the settlement of litigation or for other legal issues during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (g)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3536-108585

+ Details

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

- Definition

Amount of cash outflow for pension benefit. Includes, but is not limited to, employer contribution to fund plan asset and payment to retiree. Excludes other postretirement benefit.

+ References

+ Details

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

- Details

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Namespace Prefix:
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Period Type:

- Details

Name:	srt_CounterpartyNameAxis=cenx_PensionBenefitGuaranteeCorporationMember
Namespace Prefix:
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Balance Type:
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- Details

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Namespace Prefix:
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- Details

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- Details

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Commitments and Contingencies - Legal Contingencies (Details)				1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Oct. 01, 2021 USD ($)	Apr. 01, 2021	Aug. 18, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2022 USD ($) MW	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) MW	Sep. 30, 2021 USD ($)	Dec. 31, 2022 USD ($) MW	Dec. 31, 2013 USD ($)	Jul. 31, 2021 MW
Ravenswood Retiree Medical Benefits Changes
Loss Contingencies [Line Items]
Litigation settlement amount			$ 23,000,000
Litigation settlement period									10 years
Ravenswood retiree legal settlement				$ 5,000,000
Gain (loss) related to litigation settlement				5,500,000
Loss contingency accrual				$ 12,500,000
Litigation settlement, annual installment									$ 2,000,000
Litigation settlement installment period									9 years
Loss contingency, accrual, current									$ 2,000,000
Other liabilities									4,800,000
Pension Benefit Guarantee Corporation
Loss Contingencies [Line Items]
Required pension contributions above minimum										$ 17,400,000
Pension contributions					$ 0	$ 0	$ 0	$ 0	$ 2,400,000
Pension contributions, amended term, annual contribution	$ 2,400,000
Pension contributions, amended term, total contribution	$ 9,600,000
Pension contributions, term	4 years
Mt. Holly
Loss Contingencies [Line Items]
Short-term power agreement, supply percentage		100.00%
Power supply agreement, increase production at full capacity, percentage		75.00%
Grundartangi - HS, Landsvirkjun
Loss Contingencies [Line Items]
Underlying, derivative power, available \| MW									545
Grundartangi - Landsvirkjun
Loss Contingencies [Line Items]
Underlying, derivative power, available \| MW					25		25
Underlying, derivative power, available, extension \| MW					42		42				161
Underlying, derivative power, rate \| MW					119		119
Underlying, derivative power, available, requested \| MW											182