Common and Preferred Stock (Summary Of Components Used To Calculate Basic And Diluted Income Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to Commerce Bancshares, Inc.	$ 488,399	$ 530,765	$ 354,057
Preferred Stock Dividends, Income Statement Impact	0	0	11,966
Net Income (Loss) Available to Common Stockholders, Basic	$ 488,399	$ 530,765	$ 342,091
Basic income per common share (in dollars per share)	$ 3.86	$ 4.12	$ 2.64
Diluted income per common share (in dollars per share)	$ 3.85	$ 4.11	$ 2.64
Basic Income Per Common Share [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net income attributable to Commerce Bancshares, Inc.	$ 488,399	$ 530,765	$ 354,057
Preferred Stock Dividends, Income Statement Impact	0	0	11,966
Net Income (Loss) Available to Common Stockholders, Basic	488,399	530,765	342,091
Less income allocated to nonvested restricted stockholders	4,450	4,846	3,215
Net income available to common stockholders	$ 483,949	$ 525,919	$ 338,876
Weighted average common shares outstanding	125,275	127,738	128,286
Basic income per common share (in dollars per share)	$ 3.86	$ 4.12	$ 2.64
Diluted Income Per Common Share [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Net Income (Loss) Available to Common Stockholders, Diluted	$ 488,399	$ 530,765	$ 342,091
Less income allocated to nonvested restricted stockholders	4,442	4,838	3,211
Net income available to common stockholders	$ 483,957	$ 525,927	$ 338,880
Weighted average common shares outstanding	125,275	127,738	128,286
Net effect of the assumed exercise of stock-based awards -- based on the treasury stock method using the average market price for the respective periods	285	300	248
Weighted average diluted common shares outstanding	125,560	128,038	128,534
Diluted income per common share (in dollars per share)	$ 3.85	$ 4.11	$ 2.64