Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 262,784us-gaap_ProfitLoss	$ 261,117us-gaap_ProfitLoss	$ 271,439us-gaap_ProfitLoss
Other comprehensive income (loss):
Net unrealized gains (losses) on securities for which a portion of an other-than-temporary impairment has been recorded in earnings	(412)	958	7,566
Net unrealized gains on other securities	60,007	(138,960)	24,126
Change in pension loss	(7,233)	11,389	(5,886)
Other comprehensive income	52,362	(126,613)	25,806
Comprehensive income	315,146	134,504	297,245
Non-controlling interest expense	1,030	156	2,110
Comprehensive income attributable to Commerce Bancshares, Inc.	$ 314,116us-gaap_ComprehensiveIncomeNetOfTax	$ 134,348us-gaap_ComprehensiveIncomeNetOfTax	$ 295,135us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

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Amount after tax of other than temporary impairment (OTTI) loss on investments in available-for-sale and held-to-maturity debt securities, recognized in other comprehensive loss.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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