Fair Value of Financial Instruments (Estimated Fair Values and Fair Value Hierarchy of Financial Instruments not Recorded or Measured at Fair Value on a Nonrecurring Basis) (Details) - USD ($) $ in Thousands		Mar. 31, 2025	Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities purchased under agreements to resell		$ 642,850	$ 528,976
Held-to-maturity securities	[1]	6,713,101	6,547,647
Securities sold under agreements to repurchase		684,561	580,170
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		2,707,643	2,646,376
Cash segregated for regulatory purposes		28,065	29,895
Securities purchased under agreements to resell		642,850	528,976
Held-to-maturity securities		6,713,101	6,547,647
Bank loans		19,634,492	20,229,458
Loans held for sale		1,016,127	578,980
Securities sold under agreements to repurchase		684,561	580,170
Bank deposits		27,838,167	27,164,580
Senior notes		563,406	561,851
Debentures to Stifel Financial Capital Trusts		57,063	58,788
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		2,707,643	2,646,376
Cash segregated for regulatory purposes		28,065	29,895
Senior notes		563,406	561,851
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		642,850	528,976
Held-to-maturity securities		6,641,005	6,474,140
Bank loans		19,489,586	20,104,756
Loans held for sale		1,016,127	578,980
Securities sold under agreements to repurchase		684,561	580,170
Bank deposits		27,838,167	27,164,580
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		72,096	73,507
Bank loans		144,906	124,702
Debentures to Stifel Financial Capital Trusts		$ 57,063	$ 58,788

[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.