Parent Company Condensed Financial Statements (Condensed Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale	$ 12,238,316	$ 14,450,027
Equity Securities, FV-NI and without Readily Determinable Fair Value	12,304	9,202
Other assets	909,590	506,862
Total assets	31,875,931	36,689,088
Other liabilities	355,508	392,164
Total liabilities	29,394,354	33,240,764
Stockholders’ equity	2,465,291	3,437,298
Total liabilities and equity	31,875,931	36,689,088
Commerce Bancshares, Inc. (Parent) [Member]
Investment in consolidated subsidiary, Banks	2,008,454	2,997,775
Investment in consolidated subsidiaries, Non-banks	138,501	100,347
Cash	233,261	245,616
Debt Securities, Available-for-sale	5,207	4,805
Equity Securities, FV-NI and without Readily Determinable Fair Value	11,129	7,977
Note receivable due from bank subsidiary	50,000	50,000
Advances to subsidiaries, net of borrowings	20,529	40,525
Income tax benefits	11,987	8,645
Other assets	26,539	29,393
Total assets	2,505,607	3,485,083
Pension obligation	7,446	11,931
Other liabilities	32,870	35,854
Total liabilities	40,316	47,785
Stockholders’ equity	2,465,291	3,437,298
Total liabilities and equity	$ 2,505,607	$ 3,485,083