Annual report pursuant to Section 13 and 15(d)

Contingencies Contingencies - Sales to Major Customers (Details)

v3.8.0.1
Contingencies Contingencies - Sales to Major Customers (Details) - Customer concentration risk - Sales Revenue, Net
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Company A      
Product Information [Line Items]      
Percentage of sales to major customers 40.00% 59.00% 62.00%
Company B      
Product Information [Line Items]      
Percentage of sales to major customers 5.00% 12.00% 23.00%
Company C      
Product Information [Line Items]      
Percentage of sales to major customers 7.00% 10.00% 12.00%
All others      
Product Information [Line Items]      
Percentage of sales to major customers 48.00% 19.00% 3.00%