Consolidated Statements Of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 133,355	$ 110,080	$ 221,689	$ 315,434
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	0	(245)	0	(432)
Net unrealized gains (losses) on other securities	330	21,030	165,464	171,421
Pension loss amortization	327	389	1,038	1,166
Unrealized gains (losses) on cash flow hedge derivatives	(6,483)	14,101	66,489	36,687
Other comprehensive income (loss), net of tax	(5,826)	35,275	232,991	208,842
Comprehensive income	127,529	145,355	454,680	524,276
Non-controlling interest expense (income)	907	838	(2,479)	1,083
Comprehensive income attributable to Commerce Bancshares, Inc	$ 126,622	$ 144,517	$ 457,159	$ 523,193