Document and Entity Information	12 Months Ended
	Dec. 31, 2011
Document and Entity Information [Abstract]
Entity Registrant Name	Kaiser Aluminum Corp
Entity Central Index Key	0000811596
Document Type	8-K
Document Period End Date	Dec. 31, 2011
Amendment Flag	false
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer