Customer Concentration	3 Months Ended
Mar. 31, 2012
Customer Concentration [Abstract]
Customer Concentration	11. Customer Concentration During both the three months ended March 31, 2012 and 2011, no single client accounted for more than 10% of total revenue. One client accounted for 14.3% and 15.7% of trading volumes during the three months ended March 31, 2012 and 2011, respectively.

The entire disclosure for any concentrations existing at the date of the financial statements that make an entity vulnerable to a reasonably possible, near-term, severe impact. This disclosure informs financial statement users about the general nature of the risk associated with the concentration, and may indicate the percentage of concentration risk as of the balance sheet date.

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+ Details