Bank Loans (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at lower of cost or market	$ 262,063		$ 262,063		$ 226,068
Gains (losses) recognized from sale of loans	2,600	$ 3,200	7,800	$ 9,400
Impaired loans more than 90 days past due	24,200		24,200		29,200
Troubled debt restructurings	9,100		9,100		9,100
Specific allowance	$ 8,701		$ 8,701		$ 9,105
Collateralized loan portfolio	98.60%		98.60%		97.20%
Stifel Financial Corp. [Member] | Executive Officers Directors and Their Affiliates [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding amount	$ 25,200		$ 25,200		$ 8,400
Stifel Bancorp [Member] | Executive Officers Directors and Their Affiliates [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding amount	$ 4,000		$ 4,000		$ 4,000