| Document and Entity Information | Sep. 27, 2019 |
| Cover page. | |
| Entity Registrant Name | OLIN CORPORATION |
| Entity Central Index Key | 0000074303 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Sep. 27, 2019 |
| Entity Incorporation, State or Country Code | VA |
| Entity File Number | 1-1070 |
| Entity Tax Identification Number | 13-1872319 |
| Entity Address, Address Line One | 190 Carondelet Plaza, |
| Entity Address, Address Line Two | Suite 1530 |
| Entity Address, City or Town | Clayton, |
| Entity Address, State or Province | MO |
| Entity Address, Postal Zip Code | 63105 |
| City Area Code | 314 |
| Local Phone Number | 480-1400 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $1.00 par value per share |
| Trading Symbol | OLN |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
