Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 111,324	$ 78,989	$ 213,385	$ 150,691
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	(123)	76	(78)	171
Net unrealized gains (losses) on other securities	(19,489)	11,241	(93,210)	30,243
Pension loss amortization	394	341	787	681
Other comprehensive income (loss), net of tax	(19,218)	11,658	(92,501)	31,095
Comprehensive income	92,106	90,647	120,884	181,786
Non-controlling interest expense (income)	994	29	2,071	227
Comprehensive income attributable to Commerce Bancshares, Inc	$ 91,112	$ 90,618	$ 118,813	$ 181,559