Document and Entity Information Document - USD ($)	12 Months Ended
	Dec. 31, 2022	Feb. 16, 2023	Jun. 30, 2022
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 7,329,000,000
Entity Common Stock, Shares Outstanding		124,801,957
Documents Incorporated by Reference [Text Block]	Portions of the Registrant’s definitive proxy statement for its 2023 annual meeting of shareholders, which will be filed within 120 days of December 31, 2022, are incorporated by reference into Part III of this Report.
Entity Central Index Key	0000022356
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false