Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Stock-Based Compensation Plan Activity (Details)

v3.20.1
Stockholders' Equity - Stock-Based Compensation Plan Activity (Details) - $ / shares
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Number of Shares Available for Grant          
Available for future grants (in shares) 805,749 1,065,003 2,402,326 805,749 1,065,003
Granted (in shares) (3,468,296) (640,275)      
Forfeited (in shares) 564,873 381,021      
Authorized (in shares) 4,500,000        
Beginning balance, number of shares available for grant 805,749 1,065,003      
Number of Shares          
Beginning balance (in shares) 1,694,068 578,813      
Options granted (in shares) 2,197,074 1,269,925      
Exercise of options to purchase common stock (in shares) 0 0      
Options forfeited (in shares) (427,450) (154,670)      
Ending balance (in shares) 3,463,692 1,694,068      
Weighted-average exercise (dollars per share)     $ 3.71 $ 4.57 $ 6.51
Options granted, weighted average exercise price (in usd per share) $ 3.19 $ 3.99      
Options exercised, weighted average exercise price (in usd per share) 0 0      
Options forfeited, weighted-average price (in usd per share) $ 4.46 7.00      
Number of options granted 840,000        
Weighted-average grant-date fair value (dollars per share) $ 1.49 $ 1.71      
Restricted Stock (in shares)          
Number of Shares          
Beginning balance (in shares) 96,623 180,951      
Options granted (in shares) 1,271,222 207,623      
Exercise of options to purchase common stock (in shares) (970,630) (65,600)      
Options forfeited (in shares) (137,423) (226,351)      
Ending balance (in shares) 259,792 96,623      
Weighted-average exercise (dollars per share)     $ 1.83 $ 4.01 $ 7.40
Options granted, weighted average exercise price (in usd per share) $ 1.52 $ 2.42      
Options exercised, weighted average exercise price (in usd per share) 1.63 5.78      
Options forfeited, weighted-average price (in usd per share) $ 1.85 $ 4.74