Regulatory Capital Requirements (Schedule Of Total Risk-Based, Tier 1 Risk-Based, And Tier 1 Leverage Ratios) (Details) $ in Thousands	Sep. 30, 2018 USD ($)
Stifel Financial Corp. [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 2,081,840
Tier 1 capital, Actual Ratio	18.00%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 695,439
Tier 1 capital For Capital Adequacy Purposes, Ratio	6.00%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 927,252
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%
Total capital, Actual Amount	$ 2,232,951
Total capital, Actual Ratio	19.30%
Total capital For Capital Adequacy Purposes, Amount	$ 927,252
Total capital For Capital Adequacy Purposes, Ratio	8.00%
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 1,159,066
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%
Tier 1 leverage, Actual Amount	$ 2,081,840
Tier 1 leverage, Actual Ratio	9.60%
Tier 1 leverage For Capital Adequacy Purposes, Amount	$ 864,465
Tier 1 leverage For Capital Adequacy Purposes, Ratio	4.00%
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 1,080,581
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%
Stifel Financial Corp. [Member] | Common Stock [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 1,931,840
Tier 1 capital, Actual Ratio	16.70%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 521,580
Tier 1 capital For Capital Adequacy Purposes, Ratio	4.50%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 753,393
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%
Stifel Bank & Trust [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 1,142,936
Tier 1 capital, Actual Ratio	14.20%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 481,939
Tier 1 capital For Capital Adequacy Purposes, Ratio	6.00%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 642,585
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%
Total capital, Actual Amount	$ 1,223,636
Total capital, Actual Ratio	15.20%
Total capital For Capital Adequacy Purposes, Amount	$ 642,585
Total capital For Capital Adequacy Purposes, Ratio	8.00%
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 803,231
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%
Tier 1 leverage, Actual Amount	$ 1,142,936
Tier 1 leverage, Actual Ratio	7.00%
Tier 1 leverage For Capital Adequacy Purposes, Amount	$ 651,837
Tier 1 leverage For Capital Adequacy Purposes, Ratio	4.00%
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 814,797
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%
Stifel Bank & Trust [Member] | Common Stock [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 1,142,936
Tier 1 capital, Actual Ratio	14.20%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 361,454
Tier 1 capital For Capital Adequacy Purposes, Ratio	4.50%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 522,100
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%
Stifel Bank [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 75,385
Tier 1 capital, Actual Ratio	13.80%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 32,888
Tier 1 capital For Capital Adequacy Purposes, Ratio	6.00%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 43,851
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%
Total capital, Actual Amount	$ 82,246
Total capital, Actual Ratio	15.00%
Total capital For Capital Adequacy Purposes, Amount	$ 43,851
Total capital For Capital Adequacy Purposes, Ratio	8.00%
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 54,814
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%
Tier 1 leverage, Actual Amount	$ 75,385
Tier 1 leverage, Actual Ratio	12.50%
Tier 1 leverage For Capital Adequacy Purposes, Amount	$ 24,137
Tier 1 leverage For Capital Adequacy Purposes, Ratio	4.00%
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 30,171
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%
Stifel Bank [Member] | Common Stock [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 75,385
Tier 1 capital, Actual Ratio	13.80%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 24,666
Tier 1 capital For Capital Adequacy Purposes, Ratio	4.50%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 35,629
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%