Short-Term Borrowings (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Daily borrowings under credit arrangements	$ 414,900,000		$ 414,900,000
Uncommitted secured lines of credit			680,000,000
Committed revolving credit facility	100,000,000		100,000,000
Interest rate percentage over one-month Eurocurrency rate			1.00%
Compensating balances	0		0
Outstanding on our revolving credit facility	0		0
Short-term borrowings from banks	368,000,000		368,000,000		55,700,000
Company-owned securities collateralized value	847,320,000		847,320,000		686,997,000
Weighted average daily interest rates	1.18%		1.18%		1.22%
Debt instrument interest rate during period	1.12%	1.33%	1.13%	1.25%
Average outstanding securities	252,300,000	414,700,000	175,400,000	312,600,000
Stock loan balance	25,136,000		25,136,000		40,101,000
Stifel Nicolaus [Member]
Short-term borrowings from banks	368,000,000		368,000,000
Debt instrument interest rate during period	0.19%	0.13%	0.18%	0.13%
Average outstanding securities	68,100,000	81,000,000	70,500,000	72,900,000
Company Owned Securities [Member]
Company-owned securities collateralized value	573,600,000		573,600,000		440,800,000
Stock Loan Balance [Member] | Stifel Nicolaus [Member]
Weighted average daily interest rates	0.22%		0.22%		0.16%
Stock loan balance	$ 25,100,000		$ 25,100,000		$ 40,100,000