Customer Concentration (Details Textual)	12 Months Ended
	Dec. 31, 2011 customer	Dec. 31, 2010 customer	Dec. 31, 2009 customer
Customer Concentration (Textual) [Abstract]
Concentration risk number of customer	0	0	0
Total revenue, accounted for single client	More than 10%	More than 10%	More than 10%
Percentage of trading volumes by single client	14.60%	15.80%	12.10%