Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement of Other Comprehensive Income [Abstract]
Net income	$ 68,445	$ 66,786	$ 195,292	$ 204,836
Available for sale debt securities for which a portion of an other-than-temporary impairment (OTTI) has been recorded in earnings:
Net unrealized gains (losses) on OTTI securities	(130)	3,695	887	7,592
Other available for sale investment securities:
Net unrealized gains on other securities	3,815	25,160	(112,632)	46,552
Prepaid pension cost:
Pension loss amortization	476	453	1,426	1,358
Other comprehensive income	4,161	29,308	(110,319)	55,502
Comprehensive income	72,606	96,094	84,973	260,338
Non-controlling interest expense	221	780	246	2,298
Comprehensive income attributable to Commerce Bancshares, Inc	$ 72,385	$ 95,314	$ 84,727	$ 258,040

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