Parent Company Condensed Financial Statements (Condensed Statements Of Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest and dividends on investment securities	$ 278,755	$ 313,892	$ 236,278
Salaries and employee benefits	584,063	554,047	525,248
Data processing fees paid to affiliates	118,758	110,692	101,792
Other	77,890	63,051	64,519
Total non-interest expense	930,982	848,777	805,901
Income tax expense (benefit)	134,549	132,358	145,711
NET INCOME ATTRIBUTABLE TO COMMERCE BANCSHARES, INC.	477,060	488,399	530,765
Commerce Bancshares, Inc. (Parent) [Member]
Dividends received from consolidated subsidiary banks	280,000	300,001	340,001
Earnings of consolidated subsidiaries, net of dividends	203,570	203,965	200,461
Interest and dividends on investment securities	2,905	2,480	2,162
Management fees charged subsidiaries	47,773	38,632	36,310
Investment securities gains (losses)	(621)	(872)	79
Net interest income on advances and note to subsidiaries	2,636	1,403	51
Other	2,842	3,709	2,927
Total income	539,105	549,318	581,991
Salaries and employee benefits	41,549	44,352	37,362
Professional fees	3,580	2,740	2,006
Data processing fees paid to affiliates	3,347	3,173	2,834
Other	16,264	15,595	12,973
Total non-interest expense	64,740	65,860	55,175
Income tax expense (benefit)	(2,695)	(4,941)	(3,949)
NET INCOME ATTRIBUTABLE TO COMMERCE BANCSHARES, INC.	$ 477,060	$ 488,399	$ 530,765