XML 240 R89.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Pension and Other Postretirement Benefits - Participation in Multi-Employer Pension Plans (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Retirement Benefits [Abstract] |  |  |  |
EIN | 236648508 |  |  |
PN | 499 |  |  |
Pension protection act zone status |  |  | Green | Green
Subject to financial improvement/rehabilitation plan | No |  |  |
Contributions of century aluminum company | $ 40 | $ 200 | $ 1,600 |
Withdrawal from Plan Probable | No |  |  |
Surcharge Imposed | No |  |  |
Expiration date of collective bargaining agreement | Mar. 31, 2026 |  |  |

X
- Definition Whether withdrawal from the multi-employer pension plan is probable. + References No definition available. + Details
Name: | cenx_MultiemployerPlanPensionSignificantWithdrawalFromPlanProbable
Namespace Prefix: | cenx_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_CompensationAndRetirementDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Indicates certified zone status of multiemployer pension plan determined to be individually significant. Acceptable values are "Green", "Yellow", "Orange", "Red", "Other", and "NA". + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480547/715-80-55-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (c) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480576/715-80-50-5 + Details
Name: | us-gaap_MultiemployerPlanPensionSignificantCertifiedZoneStatusFixedList
Namespace Prefix: | us-gaap_
Data Type: | us-types:zoneStatusItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expiration date of collective-bargaining arrangement (CBA) requiring contribution to multiemployer pension plan determined to be individually significant, in YYYY-MM-DD format. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480547/715-80-55-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480576/715-80-50-5 + Details
Name: | us-gaap_MultiemployerPlanPensionSignificantCollectiveBargainingArrangementExpirationDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cost for employer contribution to multiemployer pension plan determined to be individually significant. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480547/715-80-55-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (e)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480576/715-80-50-5 + Details
Name: | us-gaap_MultiemployerPlanPensionSignificantEmployerContributionCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Employer Identification Number (EIN) or Tax Identification Number (TIN) assigned by Internal Revenue Service (IRS) for multiemployer pension plan determined to be individually significant, in nine-digit numeric format. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480547/715-80-55-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480576/715-80-50-5 + Details
Name: | us-gaap_MultiemployerPlanPensionSignificantEmployerIdentificationNumber
Namespace Prefix: | us-gaap_
Data Type: | us-types:nineDigitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Indicates whether funding improvement plan or rehabilitation plan was implemented or pending for multiemployer pension plan, determined to be individually significant. Acceptable values are "No", "Pending", "Implemented", "Other", and "NA". + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480547/715-80-55-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (f)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480576/715-80-50-5 + Details
Name: | us-gaap_MultiemployerPlanPensionSignificantFundingImprovementOrRehabilitationPlanImplementationStatusFixedList
Namespace Prefix: | us-gaap_
Data Type: | us-types:fundingImprovementAndRehabilitationPlanItemType
Balance Type: | na
Period Type: | duration

X
- Definition Plan number for multiemployer pension plan determined to be individually significant, in three-digit numeric format. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480547/715-80-55-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480576/715-80-50-5 + Details
Name: | us-gaap_MultiemployerPlanPensionSignificantPlanNumber
Namespace Prefix: | us-gaap_
Data Type: | us-types:threeDigitItemType
Balance Type: | na
Period Type: | duration

X
- Definition Indicates whether employer paid surcharge to multiemployer pension plan determined to be individually significant. Acceptable values are "No", "Yes", and "NA". + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480547/715-80-55-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 80 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (f)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480576/715-80-50-5 + Details
Name: | us-gaap_MultiemployerPlanPensionSignificantSurchargeFixedList
Namespace Prefix: | us-gaap_
Data Type: | us-types:surchargeItemType
Balance Type: | na
Period Type: | duration