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Concentration of Credit Risk - Additional Information (Details) - Vendor
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
China    
Concentration Risk [Line Items]    
Number of vendors 2 2
Customer Concentration Risk | Net Revenue    
Concentration Risk [Line Items]    
Concentration risk percentage 10.00% 10.00%
Customer Concentration Risk | Net Revenue | China    
Concentration Risk [Line Items]    
Concentration risk percentage 71.00% 64.00%
Customer Concentration Risk | Trade Accounts Receivable    
Concentration Risk [Line Items]    
Concentration risk percentage 10.00% 10.00%