Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 74,226	$ 69,150	$ 224,917	$ 204,480
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	286	46	457	(352)
Net unrealized gains (losses) on other securities	24,356	(13,747)	54,599	87,887
Pension loss amortization	349	359	1,030	1,077
Other comprehensive income (loss), net of tax	24,991	(13,342)	56,086	88,612
Comprehensive income	99,217	55,808	281,003	293,092
Non-controlling interest expense (income)	(338)	605	(111)	668
Comprehensive income attributable to Commerce Bancshares, Inc	$ 99,555	$ 55,203	$ 281,114	$ 292,424