Regulatory Capital Requirements (Schedule Of Total Risk-Based, Tier 1 Risk-Based, And Tier 1 Leverage Ratios) (Details) $ in Thousands	Jun. 30, 2018 USD ($)
Stifel Bank [Member]
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 capital, Actual Amount	$ 1,111,891
Tier 1 capital, Actual Ratio	14.40%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 461,917
Tier 1 capital For Capital Adequacy Purposes, Ratio	6.00%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 615,890
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%
Total capital, Actual Amount	$ 1,185,666
Total capital, Actual Ratio	15.40%
Total capital For Capital Adequacy Purposes, Amount	$ 615,890
Total capital For Capital Adequacy Purposes, Ratio	8.00%
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 769,862
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%
Tier 1 leverage, Actual Amount	$ 1,111,891
Tier 1 leverage, Actual Ratio	7.20%
Tier 1 leverage For Capital Adequacy Purposes, Amount	$ 620,834
Tier 1 leverage For Capital Adequacy Purposes, Ratio	4.00%
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 776,042
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	$ 1,111,891
Tier 1 capital, Actual Ratio	14.40%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 346,438
Tier 1 capital For Capital Adequacy Purposes, Ratio	4.50%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 500,410
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	$ 1,977,651
Tier 1 capital, Actual Ratio	18.40%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 644,710
Tier 1 capital For Capital Adequacy Purposes, Ratio	6.00%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 859,614
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	8.00%
Total capital, Actual Amount	$ 2,051,426
Total capital, Actual Ratio	19.10%
Total capital For Capital Adequacy Purposes, Amount	$ 859,614
Total capital For Capital Adequacy Purposes, Ratio	8.00%
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 1,074,517
Total capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%
Tier 1 leverage, Actual Amount	$ 1,977,651
Tier 1 leverage, Actual Ratio	9.50%
Tier 1 leverage For Capital Adequacy Purposes, Amount	$ 831,539
Tier 1 leverage For Capital Adequacy Purposes, Ratio	4.00%
Tier 1 leverage To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 1,039,424
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	$ 1,762,240
Tier 1 capital, Actual Ratio	16.40%
Tier 1 capital For Capital Adequacy Purposes, Amount	$ 483,533
Tier 1 capital For Capital Adequacy Purposes, Ratio	4.50%
Tier 1 capital To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 698,436
Tier 1 To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.50%