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, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities purchased under agreements to resell	[1]	$ 622,361	$ 512,220
Held-to-maturity securities	[2]	4,506,385	3,710,478
Securities sold under agreements to repurchase	[3]	495,484	233,704
Bank deposits		14,502,952	13,411,935
Borrowings		140,030	256,000
Senior notes		1,015,714	1,014,940
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		675,606	618,842
Cash segregated for regulatory purposes		21,585	90,802
Securities purchased under agreements to resell		622,361	512,220
Held-to-maturity securities		4,506,385	3,710,478
Loans held for sale		262,063	226,068
Bank loans		8,330,974	6,953,328
Securities sold under agreements to repurchase		495,484	233,704
Bank deposits		13,711,447	12,702,746
Federal Home Loan Bank advances		1,064,000	745,000
Borrowings		140,030	256,000
Senior notes		1,012,374	1,044,768
Debentures to Stifel Financial Capital Trusts		68,839	64,962
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		675,606	618,842
Cash segregated for regulatory purposes		21,585	90,802
Securities purchased under agreements to resell		586,829	428,740
Securities sold under agreements to repurchase		126,378	92,278
Federal Home Loan Bank advances		1,064,000	745,000
Borrowings		140,030	256,000
Senior notes		1,012,374	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		35,532	83,480
Held-to-maturity securities		4,345,021	3,517,781
Loans held for sale		262,063	226,068
Bank loans		8,330,974	6,953,328
Securities sold under agreements to repurchase		369,106	141,426
Bank deposits		13,711,447	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		161,364	192,697
Debentures to Stifel Financial Capital Trusts		$ 68,839	$ 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 $621.5 million and $509.4 million at September 30, 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 $522.4 million and $241.4 million at September 30, 2018 and December 31, 2017, respectively.