XML 64 R52.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Derivative instruments (Details) | Sep. 30, 2016 t
--- | ---
LME Swap [Member] |
Derivative [Line Items] |
Primary aluminum capacity | 45,000
Price Swap [Member] |
Derivative [Line Items] |
Primary aluminum capacity | 8,200

X
- Definition Annual production capacity of primary aluminum (in tonnes). + References No definition available. + Details
Name: | cenx_Primaryaluminumcapacity
Namespace Prefix: | cenx_
Data Type: | num:massItemType
Balance Type: | na
Period Type: | instant

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

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=cenx_FixedtoVariableLondonMetalsExchangeSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=cenx_FixedtoFloatingSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |