v3.26.1
Cover Page - shares
 9 Months Ended
Jun. 30, 2026
Aug. 03, 2026
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Entity File Number 001-31921  
Entity Registrant Name Compass Minerals International, Inc.  
Entity Incorporation, State or Country Code DE  
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  
Title of 12(b) Security Common stock, $0.01 par value  
Trading Symbol CMP  
Security Exchange Name NYSE  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   41,980,874
Entity Central Index Key 0001227654  
Current Fiscal Year End Date --09-30  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q3  
Amendment Flag false