Quarterly report pursuant to Section 13 or 15(d)

Share-based compensation - Fair Value Assumptions (Details)

v3.5.0.2
Share-based compensation - Fair Value Assumptions (Details) - company
9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Assumptions used to estimate the fair values of the share options granted using the Black-Scholes option-pricing model    
Expected term (in years) 5 years 5 years
Expected volatility, minimum (as a percent) 68.00%  
Expected volatility (as a percent)   60.00%
Expected volatility, maximum (as a percent) 73.00%  
Risk free rate, minimum (as a percent) 0.17% 1.03%
Risk free rate, maximum (as a percent) 1.07% 1.39%
Expected dividend yield (as a percent) 0.00% 0.00%
Number of companies with similar public securities, considered for expected volatility rate computation 7