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, 2024	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities purchased under agreements to resell		$ 665,067	$ 349,849
Held-to-maturity securities	[1]	6,626,453	5,852,176
Securities sold under agreements to repurchase		657,984	417,644
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		1,913,999	3,357,095
Cash segregated for regulatory purposes		29,519	162,048
Securities purchased under agreements to resell		665,067	349,849
Held-to-maturity securities		6,626,453	5,852,176
Bank loans		19,447,489	18,259,923
Loans held for sale		465,739	423,999
Securities sold under agreements to repurchase		657,984	417,644
Bank deposits		26,182,382	25,326,174
Senior notes		592,839	1,041,217
Debentures to Stifel Financial Capital Trusts		55,508	55,507
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		1,913,999	3,357,095
Cash segregated for regulatory purposes		29,519	162,048
Senior notes		592,839	1,041,217
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		665,067	349,849
Held-to-maturity securities		6,555,074	5,758,130
Bank loans		19,447,489	18,259,923
Loans held for sale		465,739	423,999
Securities sold under agreements to repurchase		657,984	417,644
Bank deposits		26,182,382	25,326,174
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		71,379	94,046
Debentures to Stifel Financial Capital Trusts		$ 55,508	$ 55,507

[1] Held-to-maturity securities are carried in the consolidated statements of financial condition at amortized cost, and the changes in the value of these securities, other than impairment charges, are not reported on the consolidated financial statements.