Fair Value Of Financial Instruments (Estimated Fair Values Of Financial Instruments Not Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands		Jun. 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]	$ 566,041	$ 512,220
Held-to-maturity securities	[2]	4,478,399	3,710,478
Securities sold under agreements to repurchase	[3]	514,334	233,704
Bank deposits		13,890,849	13,411,935
Borrowings		243,000	256,000
Senior notes		1,015,455	1,014,940
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		454,354	618,842
Cash segregated for regulatory purposes		112,800	90,802
Securities purchased under agreements to resell		566,041	512,220
Held-to-maturity securities		4,478,399	3,710,478
Loans held for sale		210,611	226,068
Bank loans		7,291,212	6,953,328
Securities sold under agreements to repurchase		514,334	233,704
Bank deposits		13,164,993	12,702,746
Federal Home Loan Bank advances		760,000	745,000
Borrowings		243,000	256,000
Senior notes		1,020,200	1,044,768
Debentures to Stifel Financial Capital Trusts		58,204	64,962
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash		454,354	618,842
Cash segregated for regulatory purposes		112,800	90,802
Securities purchased under agreements to resell		502,063	428,740
Securities sold under agreements to repurchase		127,866	92,278
Federal Home Loan Bank advances		760,000	745,000
Borrowings		243,000	256,000
Senior notes		1,020,200	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		63,978	83,480
Held-to-maturity securities		4,317,604	3,517,781
Loans held for sale		210,611	226,068
Bank loans		7,291,212	6,953,328
Securities sold under agreements to repurchase		386,468	141,426
Bank deposits		13,164,993	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		160,795	192,697
Debentures to Stifel Financial Capital Trusts		$ 58,204	$ 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 $562.4 million and $509.4 million at June 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 $540.7 million and $241.4 million at June 30, 2018 and December 31, 2017, respectively.