Short-Term Borrowings (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Daily borrowings under credit arrangements	$ 473,700,000
Uncommitted secured lines of credit	680,000,000
Committed revolving credit facility	50,000,000
Interest rate percentage over federal funds effective rate	0.50%
Interest rate percentage over one-month Eurocurrency rate	1.00%
Short-term borrowings from banks	304,700,000	199,400,000
Company-owned securities collateralized value	607,586,000	393,888,000
Weighted average daily interest rates	1.14%	1.17%
Debt instrument interest rate during period	1.10%	1.15%	1.01%
Average outstanding securities	184,400,000	199,600,000	108,800,000
Stock loan balance	19,218,000	124,711,000
Stifel Nicolaus [Member]
Weighted average daily interest rates	0.24%	0.17%
Debt instrument interest rate during period	0.16%	0.30%	0.38%
Average outstanding securities	137,300,000	124,100,000	69,500,000
Stock loan balance	19,200,000	124,700,000
Company Owned Securities [Member]
Company-owned securities collateralized value	$ 530,700,000	$ 388,000,000