Parent Company Condensed Financial Statements (Condensed Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale	$ 9,136,853	$ 9,684,760
Equity Securities, FV-NI and without Readily Determinable Fair Value	57,442	12,701
Other assets	837,288	938,077
Total assets	31,996,627	31,701,061
Other liabilities	443,694	462,714
Total liabilities	28,664,152	28,736,831
Stockholders’ equity	3,309,881	2,944,116
Total liabilities and equity	31,996,627	31,701,061
Commerce Bancshares, Inc. (Parent) [Member]
Investment in consolidated subsidiary, Banks	2,697,961	2,390,595
Investment in consolidated subsidiaries, Non-banks	187,404	160,244
Cash	357,046	322,573
Debt Securities, Available-for-sale	5,381	5,081
Equity Securities, FV-NI and without Readily Determinable Fair Value	12,750	11,396
Note receivable due from bank subsidiary	50,000	50,000
Advances to subsidiaries, net of borrowings	1,500	1,800
Income tax receivable and deferred tax assets	9,131	10,263
Other assets	31,164	30,486
Total assets	3,352,337	2,982,438
Pension obligation	3,220	4,107
Other liabilities	39,236	34,215
Total liabilities	42,456	38,322
Stockholders’ equity	3,309,881	2,944,116
Total liabilities and equity	$ 3,352,337	$ 2,982,438