Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($)
shares in Thousands, $ in Thousands
Total
Secondary public offering
Employee stock purchase plan
Common Shares
Common Shares
Secondary public offering
Common Shares
Employee stock purchase plan
Preferred Shares
Preferred Shares
Secondary public offering
Additional Paid-In Capital
Additional Paid-In Capital
Secondary public offering
Additional Paid-In Capital
Employee stock purchase plan
Accumulated Deficit
Balance - Stockholders' Equity (Deficit) at Dec. 31, 2017 $ (6,050)     $ 3         $ 258,140     $ (264,193)
Balance - Stockholders' Equity (Deficit) (in shares) at Dec. 31, 2017       3,592     0          
Increase (Decrease) in Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity                        
Issuance of common stock   $ 38,786 $ 67   $ 8         $ 38,077 $ 67  
Issuance of common stock (in shares)         7,230 25   701        
Stock-based compensation expense 2,153               2,153      
Issuance of warrants in connection with debt modification 190               190      
Net loss (27,811)                     (27,811)
Balance - Stockholders' Equity (Deficit) at Dec. 31, 2018 7,335     $ 11         298,627     (292,004)
Balance - Stockholders' Equity (Deficit) (in shares) at Dec. 31, 2018       10,847     701          
Increase (Decrease) in Redeemable Convertible Preferred Stock and Stockholders' (Deficit) Equity                        
Issuance of common stock   $ 54,669 $ 130   $ 16         $ 54,653 $ 130  
Issuance of common stock (in shares)         16,530 71            
Exercise of stock options 21               21      
Exercise of stock options (in shares)       5                
Stock-based compensation expense 1,837               1,837      
Net loss (38,950)                     (38,950)
Balance - Stockholders' Equity (Deficit) at Dec. 31, 2019 $ 25,042     $ 27         $ 355,268     $ (330,954)
Balance - Stockholders' Equity (Deficit) (in shares) at Dec. 31, 2019       27,453     701