Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share ) (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
Earnings Per Share [Abstract]
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
Average shares used in basic computation	106,041	105,941	105,791	106,929	105,705	106,796	108,779	107,550	106,174	107,997	107,679
Dilutive effect of stock options and units									8,399	9,881	14,303
Average shares used in diluted computation	116,828	113,775	111,581	114,929	116,720	117,216	118,619	118,815	114,573	117,878	121,982
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