Document And Entity Information (USD $)
 9 Months Ended
Sep. 30, 2012
Jun. 30, 2012
Entity Registrant Name Olin Corporation  
Entity Central Index Key 0000074303  
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   $ 1,658,588,540
Entity Common Stock, Shares Outstanding 80,150,713  
Document Fiscal Year Focus 2012  
Document Fiscal Period Focus Q3  
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2012