XML 107 R132.htm IDEA: XBRL DOCUMENT v2.4.1.9

Subsequent events Subsequent events (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended	41 Months Ended	2 Months Ended
	Dec. 31, 2012	Dec. 31, 2014	Feb. 27, 2015	Feb. 26, 2015
Subsequent Event [Line Items]
Treasury stock acquired, Aggregate purchase price	$ 4,033us-gaap_TreasuryStockValueAcquiredCostMethod	$ 49,924us-gaap_TreasuryStockValueAcquiredCostMethod
Stock repurchase program, Remaining authorized repurchase amount		10,076us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Share repurchase program expansion [Member]
Subsequent Event [Line Items]
Stock Repurchase Program, Additional authorized amount				20,000cenx_StockRepurchaseProgramAdditionalAuthorizedAmount / us-gaap_SubsequentEventTypeAxis = cenx_SharerepurchaseprogramexpansionMember
Treasury stock acquired, Aggregate purchase price			5,840us-gaap_TreasuryStockValueAcquiredCostMethod / us-gaap_SubsequentEventTypeAxis = cenx_SharerepurchaseprogramexpansionMember
Stock repurchase program, Remaining authorized repurchase amount				$ 24,276us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1 / us-gaap_SubsequentEventTypeAxis = cenx_SharerepurchaseprogramexpansionMember

X

- Definition

Amount of additional stock repurchase plan authorization.

+ References

No definition available.

+ Details

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

X

- Definition

Amount remaining of a stock repurchase plan authorized.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

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

X

- Definition

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

+ Details

Name:	us-gaap_TreasuryStockValueAcquiredCostMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	us-gaap_SubsequentEventTypeAxis=cenx_SharerepurchaseprogramexpansionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: