Regulatory Capital Requirements (Schedule Of Total Risk-Based, Tier 1 Risk-Based, And Tier 1 Leverage Ratios) (Details) $ in Thousands	Sep. 30, 2017 USD ($)
Stifel Bank [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 1,007,303
Tier 1 capital, Actual Ratio	14.40%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 419,831
Tier 1 capital For Capital Adequacy Purposes, Ratio	6.00%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 559,774
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%
Total capital, Actual Amount	$ 1,070,198
Total capital, Actual Ratio	15.30%
Total capital For Capital Adequacy Purposes, Amount	$ 559,774
Total capital For Capital Adequacy Purposes, Ratio	8.00%
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 699,718
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%
Tier 1 leverage, Actual Amount	$ 1,007,303
Tier 1 leverage, Actual Ratio	7.10%
Tier 1 leverage For Capital Adequacy Purposes, Amount	$ 567,587
Tier 1 leverage For Capital Adequacy Purposes, Ratio	4.00%
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 709,484
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%
Common Stock [Member] | Stifel Bank [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 1,007,303
Tier 1 capital, Actual Ratio	14.40%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 314,873
Tier 1 capital For Capital Adequacy Purposes, Ratio	4.50%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 454,817
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%
Stifel Financial Corp. [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 1,969,702
Tier 1 capital, Actual Ratio	20.50%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 577,026
Tier 1 capital For Capital Adequacy Purposes, Ratio	6.00%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 769,368
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%
Total capital, Actual Amount	$ 2,031,937
Total capital, Actual Ratio	21.10%
Total capital For Capital Adequacy Purposes, Amount	$ 769,368
Total capital For Capital Adequacy Purposes, Ratio	8.00%
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 961,710
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%
Tier 1 leverage, Actual Amount	$ 1,969,702
Tier 1 leverage, Actual Ratio	10.40%
Tier 1 leverage For Capital Adequacy Purposes, Amount	$ 754,009
Tier 1 leverage For Capital Adequacy Purposes, Ratio	4.00%
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 942,511
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	$ 1,760,021
Tier 1 capital, Actual Ratio	18.30%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 432,769
Tier 1 capital For Capital Adequacy Purposes, Ratio	4.50%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 625,111
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%