Fair Value Of Financial Instruments (Estimated Fair Values Of Financial Instruments Not Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities purchased under agreements to resell	[1]	$ 669,002	$ 512,220
Held-to-maturity securities	[2]	3,825,399	3,710,478
Securities sold under agreements to repurchase	[3]	346,202	233,704
Bank deposits		13,329,623	13,411,935
Borrowings		316,000	256,000
Senior notes		1,015,195	1,014,940
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		432,946	618,842
Cash segregated for regulatory purposes		26,611	90,802
Securities purchased under agreements to resell		669,002	512,220
Held-to-maturity securities		3,825,399	3,710,478
Loans held for sale		261,467	226,068
Bank loans		7,005,857	6,953,328
Securities sold under agreements to repurchase		346,202	233,704
Bank deposits		12,570,404	12,702,746
Federal Home Loan Bank advances		827,000	745,000
Borrowings		316,000	256,000
Senior notes		1,028,534	1,044,768
Debentures to Stifel Financial Capital Trusts		57,718	64,962
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		432,946	618,842
Cash segregated for regulatory purposes		26,611	90,802
Securities purchased under agreements to resell		602,359	428,740
Securities sold under agreements to repurchase		94,608	92,278
Federal Home Loan Bank advances		827,000	745,000
Borrowings		316,000	256,000
Senior notes		1,028,534	1,044,768
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		66,643	83,480
Held-to-maturity securities		3,664,272	3,517,781
Loans held for sale		261,467	226,068
Bank loans		7,005,857	6,953,328
Securities sold under agreements to repurchase		251,594	141,426
Bank deposits		12,570,404	12,702,746
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		161,127	192,697
Debentures to Stifel Financial Capital Trusts		$ 57,718	$ 64,962

[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 $667.0 million and $509.4 million at March 31, 2018 and December 31, 2017, respectively.

[2] 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.

[3] Collateral pledged includes the fair value of securities pledged by our company to the counter party. These securities are included on the consolidated statements of financial condition unless we default. Collateral pledged by our company to the counter party includes U.S. government agency securities, U.S. government securities, and corporate fixed income securities with market values of $360.9 million and $241.4 million at March 31, 2018 and December 31, 2017, respectively.