Short-Term Borrowings (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Daily borrowings under credit arrangements	$ 364,000,000
Uncommitted secured lines of credit	680,000,000
Short-term borrowings from banks	187,400,000		199,400,000
Company-owned securities collateralized value	425,845,000		392,395,000
Weighted average daily interest rates	1.13%	1.00%	1.17%
Average outstanding securities	185,300,000	168,500,000
Stock loan balance	141,101,000		124,711,000
Stifel Nicolaus [Member]
Weighted average daily interest rates	0.14%		0.17%
Debt Instrument, Interest Rate During Period	2.09%	1.34%
Average outstanding securities	156,000,000	98,400,000
Stock loan balance	141,100,000		124,700,000
Company Owned Securities [Member]
Company-owned securities collateralized value	$ 283,700,000		$ 293,000,000