Entity Information (USD $)	6 Months Ended
	Jun. 30, 2011	Jul. 31, 2011	Jun. 30, 2010
Entity Registrant Name	CENTURY ALUMINUM CO
Entity Central Index Key	0000949157
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 495,000,000
Entity Common Stock, Shares Outstanding		93,214,667
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q2