Parent Company Condensed Financial Statements (Condensed Balance Sheets) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale	$ 9,684,760	$ 12,238,316
Equity Securities, FV-NI and without Readily Determinable Fair Value	12,701	12,304
Other assets	938,077	909,590
Total assets	31,701,061	31,875,931
Other liabilities	462,714	355,508
Total liabilities	28,736,831	29,394,354
Stockholders’ equity	2,944,116	2,465,291
Total liabilities and equity	31,701,061	31,875,931
Commerce Bancshares, Inc. (Parent) [Member]
Investment in consolidated subsidiary, Banks	2,390,595	2,008,454
Investment in consolidated subsidiaries, Non-banks	160,244	138,501
Cash	322,573	233,261
Debt Securities, Available-for-sale	5,081	5,207
Equity Securities, FV-NI and without Readily Determinable Fair Value	11,396	11,129
Note receivable due from bank subsidiary	50,000	50,000
Advances to subsidiaries, net of borrowings	1,800	20,529
Income tax receivable and deferred tax assets	10,263	11,987
Other assets	30,486	26,539
Total assets	2,982,438	2,505,607
Pension obligation	4,107	7,446
Other liabilities	34,215	32,870
Total liabilities	38,322	40,316
Stockholders’ equity	2,944,116	2,465,291
Total liabilities and equity	$ 2,982,438	$ 2,505,607