Bank Loans (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at lower of cost or market	$ 261,467		$ 226,068
Gains (losses) recognized from sale of loans	2,500	$ 2,900
Impaired loans more than 90 days past due	24,000		29,200
Troubled debt restructurings	9,100		9,100
Specific allowance	$ 9,109		$ 9,105
Collateralized loan portfolio	97.40%		97.20%
Stifel Financial Corp. [Member] | Executive Officers Directors and Their Affiliates [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding amount	$ 12,300		$ 8,400
Stifel Bank [Member] | Executive Officers Directors and Their Affiliates [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding amount	$ 4,000		$ 4,000