v3.19.3
Cover Page - shares
9 Months Ended
Sep. 30, 2019
Oct. 21, 2019
Cover page.    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Sep. 30, 2019  
Document Transition Report false  
Entity File Number 1-09447  
Entity Registrant Name KAISER ALUMINUM CORPORATION  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 94-3030279  
Entity Address, Address Line One 27422 Portola Parkway  
Entity Address, Address Line Two Suite 200  
Entity Address, City or Town Foothill Ranch  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 92610-2831  
City Area Code (949)  
Local Phone Number 614-1740  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Title of 12(b) Security Common stock, par value $0.01 per share  
Trading Symbol KALU  
Security Exchange Name NASDAQ  
Entity Common Stock, Shares Outstanding   15,878,619
Entity Central Index Key 0000811596  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
Amendment Flag false