Bank Loans (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for sale, at lower of cost or market	$ 210,611		$ 210,611		$ 226,068
Gains (losses) recognized from sale of loans	2,700	$ 3,400	5,200	$ 6,200
Impaired loans more than 90 days past due	24,100		24,100		29,200
Troubled debt restructurings	9,100		9,100		9,100
Specific allowance	$ 9,156		$ 9,156		$ 9,105
Collateralized loan portfolio	98.30%		98.30%		97.20%
Stifel Financial Corp. [Member] | Executive Officers Directors and Their Affiliates [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding amount	$ 12,900		$ 12,900		$ 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		$ 4,000