Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Deficit) - Additional Information (Details)

v3.19.1
Stockholders' Equity (Deficit) - Additional Information (Details) - $ / shares
1 Months Ended 3 Months Ended
Oct. 01, 2018
Aug. 31, 2017
Mar. 31, 2019
Oct. 30, 2018
Temporary Equity [Line Items]        
Voting rights per share     one vote per share  
Preferred stock shares authorized       10,000,000
Preferred stock, par value       $ 0.001
Preferred stock, outstanding       0
Series E Redeemable Convertible Preferred Stock        
Temporary Equity [Line Items]        
Preferred stock, conversion basis 1-for-0.0275      
Series C Redeemable Convertible Preferred Stock        
Temporary Equity [Line Items]        
Preferred stock, conversion basis 1-for-0.0370      
Cancellation of redeemable convertible preferred warrants 1,232,220      
Conversion of warrants to purchase of shares of common stock 687,928      
Oxford Finance LLC and Silicon Valley Bank | Series D Two Redeemable Convertible Preferred Stock | Loan and Security Agreement        
Temporary Equity [Line Items]        
Issuance of warrants to purchase shares   682,230    
Exercise price per share   $ 0.6596    
Oxford Finance LLC and Silicon Valley Bank | Series E Redeemable Convertible Preferred Stock | Loan and Security Agreement        
Temporary Equity [Line Items]        
Issuance of warrants to purchase shares   1,682,871    
Exercise price per share   $ 0.2674    
Term of warrant exercisable   10 years