v3.25.2
Document and Entity Information Document - shares
6 Months Ended
Jun. 30, 2025
Aug. 04, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2025  
Document Transition Report false  
Entity File Number 001-36502  
Entity Registrant Name COMMERCE BANCSHARES, INC.  
Entity Incorporation, State or Country Code MO  
Entity Tax Identification Number 43-0889454  
Entity Address, Address Line One 1000 Walnut  
Entity Address, City or Town Kansas City,  
Entity Address, State or Province MO  
Entity Address, Postal Zip Code 64106  
City Area Code 816  
Local Phone Number 234-2000  
Title of 12(b) Security $5 Par Value Common Stock  
Trading Symbol CBSH  
Security Exchange Name NASDAQ  
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  
Entity Common Stock, Shares Outstanding   133,438,915
Entity Central Index Key 0000022356  
Document Fiscal Year Focus --12-31  
Document Fiscal Year Focus 2025  
Document Fiscal Period Focus Q2  
Amendment Flag false