Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 319,900	$ 276,854	$ 266,975
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	(341)	(518)
Net unrealized gains (losses) on other securities	3,022	(22,422)	(31,517)
Change in pension loss	(301)	1,268	2,412
Other comprehensive income (loss)	3,133	(21,495)	(29,623)
Comprehensive income	323,033	255,359	237,352
Non-controlling interest expense	517	1,463	3,245
Comprehensive income attributable to Commerce Bancshares, Inc.	$ 322,516	$ 253,896	$ 234,107