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Segment, Customer Concentration and Geographical Information - Additional Information (Detail)
12 Months Ended
Dec. 31, 2018
Business_Unit
Location
Dec. 31, 2017
Location
Revenue, Major Customer [Line Items]    
Number of primary business units | Business_Unit 2  
Number of geographic locations | Location 3 3
Customer Concentration Risk [Member] | Accounts Receivable [Member]    
Revenue, Major Customer [Line Items]    
Concentration percentage 82.00% 72.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Sprint and Fast Spring [Member]    
Revenue, Major Customer [Line Items]    
Concentration percentage 84.00% 72.00%