Bank Loans (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage loans held for sale	$ 394,017		$ 394,017		$ 551,248
Gains (losses) recognized from sale of loans	7,500	$ 10,500	21,400	$ 13,000
Accrued interest receivable	22,600		22,600		20,800
Provision for credit losses	(4,204)	13,168	(7,631)	32,146
Impaired loans more than 90 days past due	9,700		9,700		13,800
Troubled debt restructurings	200		200		200
Specific allowance	$ 4,100		$ 4,100		$ 8,200
Collateralized loan portfolio	99.00%		99.00%		98.80%
Residential Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans pledged as collateral	$ 4,200,000		$ 4,200,000		$ 4,200,000
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans pledged as collateral	3,800,000		3,800,000		3,800,000
Provision for credit losses	(1,157)	2,482	3,323	6,292
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage loans held for sale	394,000		394,000		551,200
Unfunded Commitment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	5,500	$ 6,000	7,300	$ 3,100
Stifel Bancorp [Member] | Executive Officers and Directors [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding amount	25,500		25,500		23,600
Stifel Bancorp [Member] | Executive Officers and Directors of Certain Affiliated Entities [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans outstanding amount	$ 25,500		$ 25,500		$ 23,600