Short-Term Borrowings (Details) (USD $)	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Jun. 30, 2011	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Daily borrowings under credit arrangements	$ 401,200,000			$ 401,200,000
Compensating balance requirements			NO
Short-term borrowings from banks						109,600,000
Weighted average daily interest rates	1.09%			1.09%		1.05%
Debt Instrument, Interest Rate During Period	1.15%	1.28%		1.11%	1.09%
Average outstanding securities	212,400,000	91,900,000		196,000,000	108,300,000
Stock loan balance	119,533,000			119,533,000		27,907,000
Company Owned Securities [Member]
Company-owned securities collateralized value	302,200,000			302,200,000		162,600,000
Stifel Nicolaus [Member]
Weighted average daily interest rates	0.31%			0.31%		0.26%
Debt Instrument, Interest Rate During Period	1.36%	1.31%		1.36%	1.48%
Average outstanding securities	121,200,000	99,500,000		113,900,000	66,300,000
Stock loan balance	$ 119,500,000			$ 119,500,000		$ 27,900,000