Quarterly report pursuant to Section 13 or 15(d)

Subsequent events (Details)

v3.20.2
Subsequent events (Details) - USD ($)
$ / shares in Units, $ in Millions
 1 Months Ended
Oct. 01, 2020
Oct. 31, 2020
Sep. 30, 2020
Jun. 24, 2020
Jun. 23, 2020
Dec. 31, 2019
Dec. 12, 2018
Subsequent Event [Line Items]              
Unit price (in dollars per share)             $ 1.95
Common stock, par value (in dollars per share)     $ 0.001     $ 0.001  
Warrants, exercise price (in dollars per share)       $ 4.25 $ 5.00    
Number of warrants included in each unit (in shares)             1
Series F private placement              
Subsequent Event [Line Items]              
Common stock, par value (in dollars per share)     $ 0.001        
Subsequent events              
Subsequent Event [Line Items]              
Units issued upon conversion (in shares)   3,500          
Number of options repriced (in shares) 6,077,731            
Options repriced, exercise price premium 20.00%            
Options repriced, exercise price (in dollars per share) $ 0.60            
Subsequent events | Series F private placement              
Subsequent Event [Line Items]              
Unit price (in dollars per share)   $ 1,000          
Preferred stock, conversion terms, value of common stock per share (in dollars per share)   $ 0.50          
Term of warrants   6 years          
Warrants, exercise price (in dollars per share)   $ 0.75          
Gross cash proceeds   $ 21.7          
Number of warrants included in each unit (in shares)   1          
Subsequent events | Officers and directors | Series F private placement              
Subsequent Event [Line Items]              
Gross cash proceeds   $ 11.5          
Subsequent events | Series F Preferred Stock              
Subsequent Event [Line Items]              
Preferred stock, authorized (in shares) 30,000            
Subsequent events | Series F Preferred Stock | Series F private placement              
Subsequent Event [Line Items]              
Preferred stock, par value (in dollars per share)   $ 0.001          
Number of shares of stock included in each unit (in shares)   1