v2.4.0.6
Document and Entity Information (USD $)
In Millions, except Share data, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Feb. 13, 2013
Jun. 30, 2012
Document and Entity Information [Abstract]      
Entity Registrant Name Kaiser Aluminum Corp    
Entity Central Index Key 0000811596    
Document Type 10-K    
Document Period End Date Dec. 31, 2012    
Amendment Flag false    
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus FY    
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 Large Accelerated Filer    
Entity Public Float     $ 974.3
Entity Common Stock, Shares Outstanding   19,313,235