Quarterly report pursuant to Section 13 or 15(d)

Major Customers and Vendors (Details)

v3.10.0.1
Major Customers and Vendors (Details)
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2018
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Jun. 30, 2017
customer
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Jun. 30, 2018
customer
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Jun. 30, 2017
customer
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Dec. 31, 2017
customer
Purchases | Vendor concentration risk          
Significant Customers and Vendors          
Number of vendors | item 2 2 2 2  
Purchases | Vendor concentration risk | Major vendor one          
Significant Customers and Vendors          
Percentage of concentration risk 20.80% 22.00% 26.50% 26.60%  
Purchases | Vendor concentration risk | Major vendor two          
Significant Customers and Vendors          
Percentage of concentration risk 14.60% 14.90% 14.60% 14.10%  
Net sales | Customer concentration risk          
Significant Customers and Vendors          
Number of customers 2 2 2 2  
Net sales | Customer one | Customer concentration risk          
Significant Customers and Vendors          
Percentage of concentration risk 18.40% 21.00% 22.00% 20.00%  
Net sales | Customer two | Customer concentration risk          
Significant Customers and Vendors          
Percentage of concentration risk 16.10% 16.10% 17.10% 18.20%  
Net accounts receivable | Customer concentration risk          
Significant Customers and Vendors          
Number of customers     2   2
Net accounts receivable | Customer one | Customer concentration risk          
Significant Customers and Vendors          
Percentage of concentration risk     32.30%   28.60%
Net accounts receivable | Customer two | Customer concentration risk          
Significant Customers and Vendors          
Percentage of concentration risk     8.40%   15.10%