Quarterly report pursuant to Section 13 or 15(d)

STOCKHOLDERS' EQUITY, Common Stock (Details)

v3.21.2
STOCKHOLDERS' EQUITY, Common Stock (Details) - USD ($)
 3 Months Ended 6 Months Ended
May 28, 2021
Feb. 03, 2021
Aug. 05, 2020
Feb. 21, 2020
Feb. 11, 2020
Jun. 30, 2021
Mar. 31, 2021
Mar. 31, 2020
Jun. 30, 2021
Jun. 30, 2020
Dec. 31, 2020
Common Stock [Abstract]                      
Common stock, shares authorized (in shares)           300,000,000     300,000,000   150,000,000
Common stock, par value (in dollars per share)           $ 0.0001     $ 0.0001   $ 0.0001
Common stock, shares outstanding (in shares)           131,872,026     131,872,026   104,902,888
Warrants outstanding (in shares)           17,073,357     17,073,357    
Common stock, available for issuance (in shares)           151,054,617     151,054,617    
Common stock issuable under agreement           $ 17,189,560 $ 41,912,515 $ 88,704,039      
Proceeds from issuance of common stock                 $ 59,102,075 $ 88,704,039  
Underwritten Public Offering [Member]                      
Common Stock [Abstract]                      
Proceeds from issuance of common stock                   $ 88,700,000  
Gross proceeds from issuance of common stock       $ 12,300,000 $ 82,300,000            
2020 Sale Agreement [Member] | Jefferies LLC [Member]                      
Common Stock [Abstract]                      
Proceeds from issuance of common stock                 $ 59,100,000    
2020 Sale Agreement [Member] | Jefferies LLC [Member] | Maximum [Member]                      
Common Stock [Abstract]                      
Common stock issuable under agreement     $ 50,000,000                
2020 Sale Agreement, As Amended [Member] | Jefferies LLC [Member] | Maximum [Member]                      
Common Stock [Abstract]                      
Common stock issuable under agreement   $ 105,400,000                  
2021 Sale Agreement [Member] | Jefferies LLC [Member] | Maximum [Member]                      
Common Stock [Abstract]                      
Common stock issuable under agreement $ 50,000,000                    
Common Stock [Member]                      
Common Stock [Abstract]                      
Warrants outstanding (in shares)           4,528,160     4,528,160   4,528,160
Common stock issuable under agreement           $ 883 $ 1,808 $ 2,703      
Common stock shares sold during the period (in shares)           8,827,045 18,080,708 27,025,000      
Common Stock [Member] | Underwritten Public Offering [Member]                      
Common Stock [Abstract]                      
Common stock shares sold during the period (in shares)       3,525,000 23,500,000            
Common Stock [Member] | 2020 Sale Agreement [Member] | Jefferies LLC [Member]                      
Common Stock [Abstract]                      
Common stock shares sold during the period (in shares)                 26,907,753    
Common Stock [Member] | 2021 Sale Agreement [Member] | Jefferies LLC [Member]                      
Common Stock [Abstract]                      
Common stock shares sold during the period (in shares) 0