Short-Term Borrowings (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Daily borrowings under credit arrangements	$ 473,700,000		$ 473,700,000
Uncommitted secured lines of credit			680,000,000
Committed revolving credit facility	50,000,000		50,000,000
Number of banks	2		2
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	282,000,000		282,000,000		199,400,000
Company-owned securities collateralized value	565,800,000		565,800,000		392,400,000
Weighted average daily interest rates	1.17%		1.17%		1.17%
Debt instrument interest rate during period	1.15%	1.12%	1.14%	1.24%
Average outstanding securities	267,000,000	206,000,000	226,200,000	187,700,000
Stock loan balance	151,313,000		151,313,000		124,711,000
Stifel Nicolaus [Member]
Weighted average daily interest rates	0.14%		0.14%		0.17%
Debt instrument interest rate during period	1.09%	1.36%	1.61%	1.35%
Average outstanding securities	143,400,000	121,800,000	149,700,000	110,200,000
Stock loan balance	151,300,000		151,300,000		124,700,000
Company Owned Securities [Member]
Company-owned securities collateralized value	$ 412,500,000		$ 412,500,000		$ 293,000,000