Parent Company Financial Information (Schedule Of Parent Company Statements Of Cash Flows) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net income	$ 106,472	$ 91,002	$ 89,484
Net (increase) decrease in trading securities	(15,662)	(4,266)	266
Other	(255)	14,464	(37,102)
Net cash provided by operating activities	213,043	179,994	146,690
Net capital expenditures for premises and equipment	(35,557)	(32,592)	(23,426)
Net cash used in investing activities	(722,372)	(979,217)	(363,652)
Cash dividends paid	(31,801)	(30,328)	(28,792)
Net purchase of treasury stock	(9,142)	(8,879)	(26,894)
Net cash provided by financing activities	935,343	603,195	559,048
Increase (decrease) in cash and due from banks	426,014	(196,028)	342,086
Cash and due from banks at beginning of year	1,033,617	1,229,645	887,559
Cash and due from banks at end of year	1,459,631	1,033,617	1,229,645
UMB Financial Corporation [Member]
Net income	106,472	91,002	89,484
Equity in earnings of subsidiaries	(117,066)	(101,225)	(98,708)
Net (increase) decrease in trading securities	(6,629)	1,325	(2,412)
Other	(6,567)	3,683	(3,389)
Net cash provided by operating activities	(23,790)	(5,215)	(15,025)
Net capital investment in subsidiaries	(6,900)	(35,701)	(27,154)
Dividends received from subsidiaries	41,000	56,750	77,600
Net capital expenditures for premises and equipment	(538)	51	90
Net cash used in investing activities	33,562	21,100	50,536
Proceeds from short-term debt	10,000	0	0
Cash dividends paid	(31,801)	(30,460)	(28,792)
Net purchase of treasury stock	129	(369)	(19,284)
Net cash provided by financing activities	(21,672)	(30,829)	(48,076)
Increase (decrease) in cash and due from banks	(11,900)	(14,944)	(12,565)
Cash and due from banks at beginning of year	17,804	32,748	45,313
Cash and due from banks at end of year	$ 5,904	$ 17,804	$ 32,748