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, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities purchased under agreements to resell	[1]	$ 436,860	$ 385,008
Held-to-maturity securities		3,335,033	2,827,883
Securities sold under agreements to repurchase	[2]	182,271	391,634
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		1,610,363	1,116,862
Cash segregated for regulatory purposes		154,374	131,374
Securities purchased under agreements to resell		436,860	385,008
Held-to-maturity securities		3,335,033	2,827,883
Bank loans		10,721,120	9,801,986
Loans held for sale		281,475	389,693
Securities sold under agreements to repurchase		182,271	391,634
Bank deposits		16,198,251	14,467,894
Senior notes		1,560,013	1,069,425
Debentures to Stifel Financial Capital Trusts		39,338	45,847
Federal Home Loan Bank advances			250,000
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		1,610,363	1,116,862
Cash segregated for regulatory purposes		154,374	131,374
Securities purchased under agreements to resell		337,095	342,132
Securities sold under agreements to repurchase			22,205
Senior notes		1,560,013	1,069,425
Federal Home Loan Bank advances			250,000
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		99,765	42,876
Held-to-maturity securities		3,179,239	2,666,773
Bank loans		10,721,120	9,801,986
Loans held for sale		281,475	389,693
Securities sold under agreements to repurchase		182,271	369,429
Bank deposits		16,198,251	14,467,894
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		155,794	161,110
Debentures to Stifel Financial Capital Trusts		$ 39,338	$ 45,847

[1] Collateral received includes securities received by our company from the counterparty. These securities are not included on the consolidated statements of financial condition unless there is an event of default. The fair value of securities pledged as collateral was $433.6 million and $385.3 million at September 30, 2020 and December 31, 2019, respectively.

[2] Collateral pledged includes the fair value of securities pledged by our company to the counterparty. These securities are included in the consolidated statements of financial condition unless we default. Collateral pledged by our company to the counterparty includes U.S. government agency securities, U.S. government securities, and corporate fixed income securities with market values of $188.5 million and $407.3 million at September 30, 2020 and December 31, 2019, respectively