Short-Term Borrowings (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 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	97,900,000		97,900,000		199,400,000
Company-owned securities collateralized value	352,283,000		352,283,000		393,888,000
Weighted average daily interest rates	1.13%		1.13%		1.17%
Debt instrument interest rate during period	1.15%	1.15%	1.15%	1.11%
Average outstanding securities	151,300,000	91,800,000	201,000,000	196,000,000
Stock loan balance	89,634,000		89,634,000		124,711,000
Stifel Nicolaus [Member]
Weighted average daily interest rates	0.15%		0.15%		0.17%
Debt instrument interest rate during period	0.93%	1.36%	1.38%	1.36%
Average outstanding securities	150,600,000	99,500,000	150,000,000	113,900,000
Stock loan balance	89,600,000		89,600,000		124,700,000
Company Owned Securities [Member]
Company-owned securities collateralized value	$ 309,400,000		$ 309,400,000		$ 388,000,000