Derivative Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
DERIVATIVE FINANCIAL INSTRUMENTS-BALANCE SHEET INFORMATION
Derivative Financial Instruments Not Designated as Hedging Instruments, Unrealized Gain/(Loss)	$ 57	$ (16)
Other Investment at Fair Value [Member] | Foreign currency forward contracts [Member]
DERIVATIVE FINANCIAL INSTRUMENTS-BALANCE SHEET INFORMATION
Derivative Financial Instruments Not Designated as Hedging Instruments, Unrealized Gain/(Loss)	66
Investments-trading [Member] | TBAs [Member]
DERIVATIVE FINANCIAL INSTRUMENTS-BALANCE SHEET INFORMATION
Derivative Financial Instruments Not Designated as Hedging Instruments, Unrealized Gain/(Loss)	38
Trading securities sold, not yet purchased [Member] | TBAs [Member]
DERIVATIVE FINANCIAL INSTRUMENTS-BALANCE SHEET INFORMATION
Derivative Financial Instruments Not Designated as Hedging Instruments, Unrealized Gain/(Loss)	$ (47)	$ (16)