Consolidated Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
INTEREST INCOME
Interest and fees on loans	$ 446,331	$ 463,511	$ 507,666
Interest on loans held for sale	361	1,115	6,091
Interest on investment securities	211,682	219,348	212,697
Interest on short-term federal funds sold and securities purchased under agreements to resell	82	55	48
Interest on long-term securities purchased under agreements to resell	19,174	13,455	2,549
Interest on deposits with banks	339	487	427
Total interest income	677,969	697,971	729,478
INTEREST EXPENSE
Savings, interest checking and money market	18,682	25,856	29,298
Time open and C.D.’s of less than $100,000	7,918	11,352	22,871
Time open and C.D.’s of $100,000 and over	7,174	9,272	13,847
Interest on federal funds purchased and securities sold under agreements to repurchase	808	1,741	2,584
Interest on other borrowings	3,481	3,680	14,946
Total interest expense	38,063	51,901	83,546
Net interest income	639,906	646,070	645,932
Provision for loan losses	27,287	51,515	100,000
Net interest income after provision for loan losses	612,619	594,555	545,932
NON-INTEREST INCOME
Bank card transaction fees	154,197	157,077	148,888
Trust fees	94,679	88,313	80,963
Deposit account charges and other fees	79,485	82,651	92,637
Capital market fees	21,066	19,846	21,098
Consumer brokerage services	10,162	10,018	9,190
Loan fees and sales	6,037	7,580	23,116
Other	34,004	27,432	29,219
Total non-interest income	399,630	392,917	405,111
INVESTMENT SECURITIES GAINS (LOSSES), NET
Impairment reversals on securities	11,223	2,190	13,058
Noncredit-related reversals on securities not expected to be sold	(12,713)	(4,727)	(18,127)
Net impairment losses	(1,490)	(2,537)	(5,069)
Realized gains on sales and fair value adjustments	6,318	13,349	3,284
Investment securities gains (losses), net	4,828	10,812	(1,785)
NON-INTEREST EXPENSE
Salaries and employee benefits	360,899	345,325	346,550
Net occupancy	45,534	46,434	46,987
Equipment	20,147	22,252	23,324
Supplies and communication	22,321	22,448	27,113
Data processing and software	73,798	68,103	67,935
Marketing	15,106	16,767	18,161
Deposit insurance	10,438	13,123	19,246
Debit overdraft litigation	0	18,300	0
Debt extinguishment	0	0	11,784
Other	70,226	64,497	70,034
Total non-interest expense	618,469	617,249	631,134
Income before income taxes	398,608	381,035	318,124
Less income taxes	127,169	121,412	96,249
Net income	271,439	259,623	221,875
Less non-controlling interest expense	2,110	3,280	165
NET INCOME ATTRIBUTABLE TO COMMERCE BANCSHARES, INC.	$ 269,329	$ 256,343	$ 221,710
Net income per common share - basic (in dollars per share)	$ 2.91	$ 2.70	$ 2.30
Net income per common share - diluted (in dollars per share)	$ 2.90	$ 2.69	$ 2.29