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Concentration of Credit Risk - Additional Information (Details) - Vendor
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 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% 10.00% 10.00%
Customer Concentration Risk | Net Revenue | China        
Concentration Risk [Line Items]        
Concentration risk percentage 75.00% 76.00% 73.00% 70.00%
Customer Concentration Risk | Trade Accounts Receivable        
Concentration Risk [Line Items]        
Concentration risk percentage 10.00% 10.00% 10.00% 10.00%