Quarterly report pursuant to Section 13 or 15(d)

Share-based compensation - Options (Details)

v3.8.0.1
Share-based compensation - Options (Details) - $ / shares
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Share-based compensation          
Number of options granted (in shares) 8,756,211 2,414,576 28,959,363 17,758,373  
Weighted average fair value (in dollars per share) $ 0.34 $ 0.74 $ 0.34 $ 0.74  
Number of options outstanding (in share) 74,145,505   74,145,505   49,237,290