Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Stock Option Activity (Details)

v3.19.2
Stock-Based Compensation - Stock Option Activity (Details) - Employee Stock Option - USD ($)
$ / shares in Units, $ in Thousands
6 Months Ended 12 Months Ended
Jun. 30, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]    
Number of shares, beginning outstanding (in shares) 2,364,823  
Number of shares, released (106,397)  
Number of shares, forfeited (329,350)  
Number of shares, ending outstanding (in shares) 1,929,076 2,364,823
Number of shares, exercisable (in shares) 1,258,784  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]    
Weighted average exercise price, beginning outstanding (in dollars per share) $ 0.9  
Weighted average exercise price, released (in dollars per share) 0.68  
Weighted average exercise price, forfeited (in dollars per share) 1.69  
Weighted average exercise price, ending outstanding (in dollars per share) 0.78 $ 0.9
Weighted average exercise price, exercisable (in dollars per share) $ 0.67  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]    
Weighted average remaining contractual term 7 years 26 days 8 years 1 month 13 days
Weighted average remaining contractual term, exercisable (in years) 6 years 3 months 22 days  
Share-Based Compensation Arrangement by Share-based Payment Award, Options, Aggregate Intrinsic Value [Abstract]    
Aggregate intrinsic value $ 4,492 $ 71,332
Aggregate intrinsic value, exercisable $ 3,067