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Fixed Assets, Net - Additional Information (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Property, Plant and Equipment [Line Items]    
Depreciation expense $ 168 $ 181
General and Administrative [Member]    
Property, Plant and Equipment [Line Items]    
Depreciation expense $ 81 $ 178