Quarterly report pursuant to Section 13 or 15(d)

Convertible Preferred Stock and Stockholders' Equity - Equity Transactions (Details)

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Convertible Preferred Stock and Stockholders' Equity - Equity Transactions (Details) - USD ($)
$ / shares in Units, $ in Millions
 1 Months Ended 3 Months Ended 12 Months Ended
Nov. 09, 2020
May 18, 2020
Apr. 23, 2020
Apr. 30, 2020
Mar. 31, 2021
Dec. 31, 2020
Feb. 06, 2020
Apr. 18, 2019
Class of Stock [Line Items]                
Issuance of common stock and warrants, net of offering costs (in shares) 236,375 60,250            
Warrants to purchase shares of Common Stock             4,553 12,756
Exercise price of warrants $ 2.55              
April 2020 Maxim Warrant                
Class of Stock [Line Items]                
Warrants to purchase shares of Common Stock       100,000 15,000 15,000    
Combined shares price         $ 0.20 $ 0.20    
Exercise price of warrants       $ 3.90        
April 2020 public offering                
Class of Stock [Line Items]                
Issuance of common stock and warrants, net of offering costs (in shares)     1,525,000          
Warrants to purchase shares of Common Stock       1,525,000        
Combined shares price     $ 3.24 $ 3.25        
Exercise price of warrants     $ 3.25 $ 0.01        
Consideration     $ 6.5          
Option to purchase additional shares or warrants, days     45 days          
Option to purchase additional shares or warrants, shares     300,000          
Warrant term     5 years          
April 2020 public offering | Prefunded common stock purchase warrants                
Class of Stock [Line Items]                
Warrants to purchase shares of Common Stock       291,000        
April 2020 public offering | Common stock purchase warrants                
Class of Stock [Line Items]                
Warrants to purchase shares of Common Stock     475,000          
Warrants to purchase shares ( per share)     2,000,000          
Exercise price of warrants       $ 3.25        
Option to purchase additional shares or warrants, shares     229,100          
April 2020 public offering | April 2020 Maxim Warrant                
Class of Stock [Line Items]                
Warrants to purchase shares of Common Stock     100,000 475,000        
Exercise price of warrants       $ 3.90