Fair Value Of Financial Instruments (Estimated Fair Values Of Financial Instruments Not Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities purchased under agreements to resell	$ 598,535	$ 217,930
Held-to-maturity securities	5,354,129	4,107,960
Securities sold under agreements to repurchase	195,451	190,955
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash	2,052,634	2,245,082
Cash segregated for regulatory purposes	26,095	172,932
Securities purchased under agreements to resell	598,535	217,930
Held-to-maturity securities	5,354,129	4,107,960
Bank loans	13,584,900	11,088,058
Loans held for sale	156,110	551,248
Securities sold under agreements to repurchase	195,451	190,955
Bank deposits	20,161,189	17,192,722
Federal Home Loan Bank advances	52,000
Senior notes	1,243,147	1,265,669
Debentures to Stifel Financial Capital Trusts	46,130	41,071
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash	2,052,634	2,245,082
Cash segregated for regulatory purposes	26,095	172,932
Securities purchased under agreements to resell	393,097	164,094
Federal Home Loan Bank advances	52,000
Senior notes	1,243,147	1,265,669
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities purchased under agreements to resell	205,438	53,836
Held-to-maturity securities	5,212,387	3,943,944
Bank loans	13,584,900	11,088,058
Loans held for sale	156,110	551,248
Securities sold under agreements to repurchase	195,451	190,955
Bank deposits	20,161,189	17,192,722
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Held-to-maturity securities	141,742	164,016
Debentures to Stifel Financial Capital Trusts	$ 46,130	$ 41,071