v3.25.2

Document and Entity Information Document	Jun. 16, 2025
Cover [Abstract]
Document Type	8-K
Document Period End Date	Jun. 16, 2025
Entity Registrant Name	Century Aluminum Company
Entity Incorporation, State or Country Code	DE
Entity File Number	001-34474
Entity Tax Identification Number	13-3070826
Entity Address, Address Line One	One South Wacker Drive
Entity Address, Address Line Two	Suite 1000
Entity Address, City or Town	Chicago
Entity Address, State or Province	IL
Entity Address, Postal Zip Code	60606
City Area Code	(312)
Local Phone Number	696-3101
Written Communications	false
Soliciting Material	false
Pre-commencement Tender Offer	false
Pre-commencement Issuer Tender Offer	false
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	CENX
Security Exchange Name	NASDAQ
Entity Emerging Growth Company	false
Entity Central Index Key	0000949157
Amendment Flag	false

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

+ References

No definition available.

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- Definition

Area code of city

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No definition available.

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- Definition

Cover page.

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No definition available.

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- Definition

For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

+ References

No definition available.

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Period Type:	duration

- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

+ References

No definition available.

+ Details

Name:	dei_DocumentType
Namespace Prefix:	dei_
Data Type:	dei:submissionTypeItemType
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- Definition

Address Line 1 such as Attn, Building Name, Street Name

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No definition available.

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Data Type:	xbrli:normalizedStringItemType
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Period Type:	duration

- Definition

Address Line 2 such as Street or Suite number

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No definition available.

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Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
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- Definition

Name of the City or Town

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No definition available.

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Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
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- Definition

Code for the postal or zip code

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No definition available.

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Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
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- Definition

Name of the state or province.

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No definition available.

+ Details

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Namespace Prefix:	dei_
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Balance Type:	na
Period Type:	duration

- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

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Namespace Prefix:	dei_
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Period Type:	duration

- Definition

Indicate if registrant meets the emerging growth company criteria.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

+ Details

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Balance Type:	na
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- Definition

Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Two-character EDGAR code representing the state or country of incorporation.

+ References

No definition available.

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Name:	dei_EntityIncorporationStateCountryCode
Namespace Prefix:	dei_
Data Type:	dei:edgarStateCountryItemType
Balance Type:	na
Period Type:	duration

- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

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Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
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- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b-2

+ Details

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Namespace Prefix:	dei_
Data Type:	dei:employerIdItemType
Balance Type:	na
Period Type:	duration

- Definition

Local phone number for entity.

+ References

No definition available.

+ Details

Name:	dei_LocalPhoneNumber
Namespace Prefix:	dei_
Data Type:	xbrli:normalizedStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 13e
-Subsection 4c

+ Details

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Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 14d
-Subsection 2b

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Data Type:	xbrli:booleanItemType
Balance Type:	na
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- Definition

Title of a 12(b) registered security.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection b

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Namespace Prefix:	dei_
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Period Type:	duration

- Definition

Name of the Exchange on which a security is registered.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 12
-Subsection d1-1

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Namespace Prefix:	dei_
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Period Type:	duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Exchange Act
-Number 240
-Section 14a
-Subsection 12

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Name:	dei_SolicitingMaterial
Namespace Prefix:	dei_
Data Type:	xbrli:booleanItemType
Balance Type:	na
Period Type:	duration

- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

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Namespace Prefix:	dei_
Data Type:	dei:tradingSymbolItemType
Balance Type:	na
Period Type:	duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Securities Act
-Number 230
-Section 425

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Period Type:	duration

CENTURY ALUMINUM CO 8-K