XML 59 R45.htm IDEA: XBRL DOCUMENT v3.8.0.1
Property and Equipment, Net - Additional Information (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Property, Plant and Equipment [Line Items]      
Depreciation expense $ 5,300 $ 2,400 $ 1,000
Property and equipment 17,405 14,779  
Accumulated depreciation 8,903 3,705  
Capitalized Software Development      
Property, Plant and Equipment [Line Items]      
Depreciation expense $ 400 400 $ 400
Installment payment period 4 years    
Property and equipment $ 1,800 1,800  
Accumulated depreciation $ 1,200 $ 900