| Cover Page | Dec. 31, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Dec. 31, 2020 |
| Entity Registrant Name | Compass Minerals International, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-31921 |
| Entity Tax Identification Number | 36-3972986 |
| Entity Address, Address Line One | 9900 West 109th Street |
| Entity Address, Address Line Two | Suite 100 |
| Entity Address, City or Town | Overland Park |
| Entity Address, State or Province | KS |
| Entity Address, Postal Zip Code | 66210 |
| City Area Code | 913 |
| Local Phone Number | 344-9200 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common stock, $0.01 par value |
| Trading Symbol | CMP |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001227654 |
| Amendment Flag | false |
