Quarterly report pursuant to Section 13 or 15(d)

Off-Balance-Sheet Risk and Concentration of Credit Risk - Additional Information (Detail)

v3.3.0.814
Off-Balance-Sheet Risk and Concentration of Credit Risk - Additional Information (Detail) - USD ($)
$ in Thousands
Sep. 30, 2015
Dec. 31, 2014
Off-Balance-Sheet Risk and Concentration of Credit Risk [Abstract]    
Receivables from clearing broker $ 51,273 $ 38,760