Quarterly report pursuant to Section 13 or 15(d)

Stock-based Compensation - Options (Details)

v3.8.0.1
Stock-based Compensation - Options (Details)
$ / shares in Units, $ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2017
USD ($)
shares
Sep. 30, 2016
USD ($)
Sep. 30, 2017
USD ($)
item
$ / shares
shares
Sep. 30, 2016
USD ($)
Stock Based Compensation        
Share-based compensation | $ $ 873 $ 1,714 $ 2,928 $ 5,166
Additional disclosures        
Shares of common stock available for future grant | shares 11,450,149   11,450,149  
Employee stock option        
Stock Based Compensation        
Number of homogenous groups for purposes of determining fair values of options | item     3  
Contractual term of the option     10 years  
Weighted-average assumptions relating to options granted        
Risk-free interest rate (as a percent) 2.10%   2.20% 1.70%
Expected term (in years) 6 years 2 months 12 days   6 years 8 months 12 days 6 years 4 months 24 days
Dividend yield (as a percent) 0.00%   0.00% 0.00%
Expected volatility (as a percent) 64.40%   63.20% 63.30%
Additional disclosures        
Total unrecognized compensation costs | $ $ 7,400   $ 7,400  
Options exercised during the period (in shares) | shares     526,281  
Employee stock option | Granted 2017        
Additional disclosures        
Options granted (in shares) | shares     3,485,175  
Grant-date weighted-average fair value (in dollars per share) | $ / shares     $ 1.36  
Employee stock option | Consultant        
Stock Based Compensation        
Contractual term of the option     10 years  
Employee stock option | Recipient of performance shares | Granted 2017        
Stock Based Compensation        
Share-based compensation | $     $ 0  
Additional disclosures        
Options granted (in shares) | shares     1,385,000  
Employee stock option | Recipient of performance shares | Vesting upon achievement of corporate performance-based milestones | Granted 2017        
Additional disclosures        
Grant date fair value of performance stock options awards | $     $ 2,000