Bank Loans (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage loans held for sale	$ 551,248	$ 389,693
Gains (losses) recognized from sale of loans	41,200	13,100	$ 8,200
Impaired loans more than 90 days past due	13,800	14,600
Troubled debt restructurings	200	200
Specific allowance	$ 8,182	$ 8,182
Collateralized loan portfolio	98.80%	98.30%
ASU 2016-13 [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in allowance for credit losses	$ 10,400
Credit Loss Reserves Net	28,300
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans pledged as collateral	3,800,000	$ 3,800,000
Accrued interest receivable	20,800
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans pledged as collateral	3,100,000	3,100,000
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage loans held for sale	551,200	389,700
Stifel Bancorp [Member] | Executive Officers and Directors [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding amount	23,600	24,500
Stifel Bancorp [Member] | Executive Officers and Directors of Certain Affiliated Entities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding amount	$ 23,600	$ 24,500