Consolidated Balance Sheets (Parenthetical) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Mortgage Loans:
Mortgages Held-for-sale, Fair Value Disclosure	$ 6,854,000	$ 9,181,000
Investment Securities:
Debt Securities, Available-for-sale, Amortized Cost	9,961,155,000	8,435,531,000
Debt Securities, Available-for-sale, Allowance for Credit Loss	$ 0	$ 0
Commerce Bancshares, Inc. stockholders' equity:
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	6,000	6,000
Common stock, par value	$ 5	$ 5
Common Stock, Shares Authorized	140,000,000	140,000,000
Common stock, shares issued	112,795,605	112,795,605
Treasury stock, shares	1,040,898	445,952