Regulatory Capital Requirements (Schedule Of Total Risk-Based, Tier 1 Risk-Based, And Tier 1 Leverage Ratios) (Details) $ in Thousands	Sep. 30, 2020 USD ($)
Stifel Financial Corp. [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 2,732,654
Tier 1 capital, Actual Ratio	0.192
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 853,616
Tier 1 capital For Capital Adequacy Purposes, Ratio	6.0
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 1,138,154
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.0
Total capital, Actual Amount	$ 2,888,681
Total capital, Actual Ratio	0.203
Total capital For Capital Adequacy Purposes, Amount	$ 1,138,154
Total capital For Capital Adequacy Purposes, Ratio	8.0
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 1,422,693
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.0
Tier 1 leverage, Actual Amount	$ 2,732,654
Tier 1 leverage, Actual Ratio	0.113
Tier 1 leverage For Capital Adequacy Purposes, Amount	$ 971,609
Tier 1 leverage For Capital Adequacy Purposes, Ratio	4.0
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 1,214,512
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.0
Stifel Financial Corp. [Member] | Common Stock [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 2,197,654
Tier 1 capital, Actual Ratio	0.154
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 640,212
Tier 1 capital For Capital Adequacy Purposes, Ratio	4.5
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 924,750
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.5
Stifel Bank & Trust [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 1,034,480
Tier 1 capital, Actual Ratio	0.117
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 529,707
Tier 1 capital For Capital Adequacy Purposes, Ratio	6.0
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 706,276
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.0
Total capital, Actual Amount	$ 1,144,843
Total capital, Actual Ratio	0.130
Total capital For Capital Adequacy Purposes, Amount	$ 706,276
Total capital For Capital Adequacy Purposes, Ratio	8.0
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 882,845
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.0
Tier 1 leverage, Actual Amount	$ 1,034,480
Tier 1 leverage, Actual Ratio	0.072
Tier 1 leverage For Capital Adequacy Purposes, Amount	$ 578,347
Tier 1 leverage For Capital Adequacy Purposes, Ratio	4.0
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 722,934
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.0
Stifel Bank & Trust [Member] | Common Stock [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 1,034,480
Tier 1 capital, Actual Ratio	0.117
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 397,280
Tier 1 capital For Capital Adequacy Purposes, Ratio	4.5
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 573,849
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.5
Stifel Bank [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 201,106
Tier 1 capital, Actual Ratio	0.180
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 67,021
Tier 1 capital For Capital Adequacy Purposes, Ratio	6.0
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 89,361
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.0
Total capital, Actual Amount	$ 215,097
Total capital, Actual Ratio	0.193
Total capital For Capital Adequacy Purposes, Amount	$ 89,361
Total capital For Capital Adequacy Purposes, Ratio	8.0
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 111,701
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.0
Tier 1 leverage, Actual Amount	$ 201,106
Tier 1 leverage, Actual Ratio	0.073
Tier 1 leverage For Capital Adequacy Purposes, Amount	$ 110,807
Tier 1 leverage For Capital Adequacy Purposes, Ratio	4.0
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 138,508
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.0
Stifel Bank [Member] | Common Stock [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 201,106
Tier 1 capital, Actual Ratio	0.180
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 50,266
Tier 1 capital For Capital Adequacy Purposes, Ratio	4.5
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 72,606
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.5