Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Operating revenues	$ 954,549	$ 782,711	$ 780,533	$ 776,214	$ 808,612	$ 686,932	$ 665,738	$ 628,797
Interest revenue	119,876	114,411	128,368	161,177	167,087	178,784	187,940	191,071	$ 523,832		$ 724,882		$ 646,449
Total revenues	1,074,425	897,122	908,901	937,391	975,699	865,716	853,678	819,868	3,817,839		3,514,961		3,194,957
Interest expense	14,515	13,822	13,084	24,357	31,448	44,144	52,891	49,448	65,778		177,931		170,076
Net revenues	1,059,910	883,300	895,817	913,034	944,251	821,572	800,787	770,420	3,752,061	[1]	3,337,030	[1]	3,024,881	[1]
Total non-interest expenses	825,209	724,907	752,857	797,928	781,658	670,818	652,805	632,611	3,100,901		2,737,892		2,490,519
Income before income tax expense	234,701	158,393	142,960	115,106	162,593	150,754	147,982	137,809	651,160		599,138		534,362
Provision for income taxes	46,232	37,866	35,073	28,517	31,925	40,632	38,225	38,370	147,688		149,152		140,394
Net income	188,469	120,527	107,887	86,589	130,668	110,122	109,757	99,439	503,472		449,986		393,968
Net income applicable to non-controlling interests					(22)	708	672	232			1,590
Net income applicable to Stifel Financial Corp.					130,690	109,414	109,085	99,207	503,472		448,396		393,968
Preferred dividends	7,677	9,897	4,843	4,844	4,843	4,844	5,288	2,344	27,261		17,319		9,375
Net income available to common shareholders	$ 180,792	$ 110,630	$ 103,044	$ 81,745	$ 125,847	$ 104,570	$ 103,797	$ 96,863	$ 476,211		$ 431,077		$ 384,593
Earnings per common share:
Basic	$ 1.70	$ 1.04	$ 0.97	$ 0.76	$ 1.19	$ 0.98	$ 0.95	$ 0.90	$ 4.49		$ 3.99		$ 3.57
Diluted	1.55	0.97	0.92	0.71	1.08	0.89	0.88	0.82	4.16		3.66		3.15
Cash dividends declared per common share	$ 0.11	$ 0.11	$ 0.11	$ 0.11	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.45		$ 0.40		$ 0.32
Weighted-average number of common shares outstanding:
Basic	106,041	105,941	105,791	106,929	105,705	106,796	108,779	107,550	106,174		107,997		107,679
Diluted	116,828	113,775	111,581	114,929	116,720	117,216	118,619	118,815	114,573		117,878		121,982

[1] No individual client accounted for more than 10 percent of total net revenues for the years ended December 31, 2020, 2019, and 2018.