Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 110,080	$ 114,069	$ 315,434	$ 327,454
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	(245)	53	(432)	(25)
Net unrealized gains (losses) on other securities	21,030	(32,232)	171,421	(125,442)
Pension loss amortization	389	393	1,166	1,180
Unrealized gains (losses) on cash flow hedge derivatives	14,101	(1,029)	36,687	(1,029)
Other comprehensive income (loss), net of tax	35,275	(32,815)	208,842	(125,316)
Comprehensive income	145,355	81,254	524,276	202,138
Non-controlling interest expense (income)	838	1,493	1,083	3,564
Comprehensive income attributable to Commerce Bancshares, Inc	$ 144,517	$ 79,761	$ 523,193	$ 198,574