Annual report pursuant to Section 13 and 15(d)

Convertible Preferred Stock and Stockholders' Equity - Warrants for shares of common stock (Details)

v3.20.4
Convertible Preferred Stock and Stockholders' Equity - Warrants for shares of common stock (Details)
 1 Months Ended 12 Months Ended
Oct. 16, 2020
shares
Jul. 27, 2020
USD ($)
shares
May 21, 2020
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Apr. 23, 2020
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$ / shares
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Apr. 30, 2020
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$ / shares
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Mar. 31, 2020
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$ / shares
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Aug. 31, 2019
$ / shares
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Jul. 31, 2019
$ / shares
shares
May 31, 2019
$ / shares
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Apr. 30, 2019
$ / shares
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Dec. 31, 2020
USD ($)
$ / shares
shares
Dec. 31, 2019
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Jan. 31, 2021
$ / shares
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Nov. 09, 2020
$ / shares
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Apr. 18, 2019
USD ($)
shares
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares                           45,534 12,756
Exercise price of warrants | $ / shares                           $ 2.55  
Fair value of warrant | $                             $ 250,000
Deemed dividend from warrant repricing | $                     $ 134,000 $ 0      
Shares issued on exercise of warrants | shares 75,000   122,272                        
Number of shares available for grant | shares                     352        
Alexander Capital, LP.                              
Class of Stock [Line Items]                              
Option To Purchase Additional Shares Or Warrants | shares                     20,722        
Common Shares                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares                           236,369  
LTSI                              
Class of Stock [Line Items]                              
Common stock authorized for issuance | shares                     672,180        
LTSI | Mr. Oliva                              
Class of Stock [Line Items]                              
Accelerated vesting | shares   7,500                          
LTSI | Restricted stock units                              
Class of Stock [Line Items]                              
Accelerated vesting | shares   39,429                          
Stock based compensation charge in connection with acceleration of vesting | $   $ 649,000                          
Bonus expense | $   $ 57,000                          
June 4th Purchase Agreement                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares                     2,275,000        
Exercise price of warrants | $ / shares                     $ 2.55        
Fair value of warrant | $                     $ 3,153,000        
Common Stock Price | $ / shares                     $ 2.52        
June 9th Purchase Agreement                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares                     2,040,000        
Exercise price of warrants | $ / shares                     $ 2.61        
Fair value of warrant | $                     $ 2,375,000        
Common Stock Price | $ / shares                     $ 2.25        
April 2020 public offering                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares       1,525,000 1,525,000                    
Exercise price of warrants | $ / shares         $ 3.25                    
Fair value of warrant | $         $ 2,606,000                    
Common Stock Price | $ / shares         $ 2.50                    
Proceeds from Issuance of Warrants | $       $ 6.50                      
Option To Purchase Additional Shares Or Warrants | shares       300,000                      
April 2020 public offering | Common Shares                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares       2,000,000                      
Warrant [Member] | Lippert Heishorn Associates Inc [Member]                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares               2,000              
Exercise price of warrants | $ / shares               $ 24.80              
Common Stock Price | $ / shares               $ 23.20              
Warrant [Member] | DFC Advisory Services, LLC [Member]                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares             2,500                
Exercise price of warrants | $ / shares             $ 26.20                
Common Stock Price | $ / shares             $ 20.20                
Warrant [Member] | Walsh [Member]                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares                   12,756          
Exercise price of warrants | $ / shares                   $ 39.60          
Common Stock Price | $ / shares                   $ 2.08          
Warrant [Member] | Alexander Capital, LP.                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares                 6,114 2,041          
Exercise price of warrants | $ / shares                 $ 33.20 $ 43.60          
Common Stock Price | $ / shares                 $ 27.20 $ 41.60 15.80        
Combined shares price | $ / shares                     $ 0.20        
Warrant [Member] | Subsequent Events                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares                         1,221,675    
Exercise price of warrants | $ / shares                         $ 4.20    
March 2020 Warrant                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares           227,679                  
Exercise price of warrants | $ / shares           $ 6.40                  
Fair value of warrant | $           $ 625,000                  
Common Stock Price | $ / shares           $ 5.40                  
March 2020 Maxim Warrant                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares           20,400                  
Prefunded common stock purchase warrants | April 2020 public offering                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares       475,000 475,000                    
Exercise price of warrants | $ / shares         $ 0.01                    
Fair value of warrant | $         $ 475,000                    
Combined shares price | $ / shares       $ 3.24                      
Proceeds from Issuance of Warrants | $         $ 4,750                    
Common stock purchase warrants                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares                           236,369  
Common stock purchase warrants | April 2020 public offering                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares       229,100                      
Exercise price of warrants | $ / shares       $ 3.25                      
Combined shares price | $ / shares       $ 3.25                      
Option To Purchase Additional Shares Or Warrants | shares       300,000                      
April 2020 Maxim Warrant                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares         100,000                    
Exercise price of warrants | $ / shares         $ 3.90                    
Fair value of warrant | $         $ 106,000                    
Common Stock Price | $ / shares         $ 2.50                    
April 2020 Maxim Warrant | April 2020 public offering                              
Class of Stock [Line Items]                              
Warrants to purchase shares of Common Stock | shares       100,000.00 291,000                    
Exercise price of warrants | $ / shares       $ 3.90                      
Dividend Yield | June 4th Purchase Agreement                              
Class of Stock [Line Items]                              
Measurement input                     0.0        
Dividend Yield | June 9th Purchase Agreement                              
Class of Stock [Line Items]                              
Measurement input                     0.0        
Dividend Yield | April 2020 public offering                              
Class of Stock [Line Items]                              
Measurement input         0.0                    
Dividend Yield | Warrant [Member] | Lippert Heishorn Associates Inc [Member]                              
Class of Stock [Line Items]                              
Measurement input               0              
Dividend Yield | Warrant [Member] | DFC Advisory Services, LLC [Member]                              
Class of Stock [Line Items]                              
Measurement input             0                
Dividend Yield | Warrant [Member] | Walsh [Member]                              
Class of Stock [Line Items]                              
Measurement input                   0          
Dividend Yield | Warrant [Member] | Alexander Capital, LP.                              
Class of Stock [Line Items]                              
Measurement input                 0 0          
Dividend Yield | March 2020 Warrant                              
Class of Stock [Line Items]                              
Measurement input           0.0                  
Dividend Yield | April 2020 Maxim Warrant                              
Class of Stock [Line Items]                              
Measurement input         0                    
Volatility | June 4th Purchase Agreement                              
Class of Stock [Line Items]                              
Measurement input                     64.0        
Volatility | June 9th Purchase Agreement                              
Class of Stock [Line Items]                              
Measurement input                     64.0        
Volatility | April 2020 public offering                              
Class of Stock [Line Items]                              
Measurement input         64.0                    
Volatility | Warrant [Member] | Lippert Heishorn Associates Inc [Member]                              
Class of Stock [Line Items]                              
Measurement input               58              
Volatility | Warrant [Member] | DFC Advisory Services, LLC [Member]                              
Class of Stock [Line Items]                              
Measurement input             58                
Volatility | Warrant [Member] | Alexander Capital, LP.                              
Class of Stock [Line Items]                              
Measurement input                 60 59          
Volatility | March 2020 Warrant                              
Class of Stock [Line Items]                              
Measurement input           61.0                  
Volatility | April 2020 Maxim Warrant                              
Class of Stock [Line Items]                              
Measurement input         64                    
Risk-free rate of interest | June 4th Purchase Agreement                              
Class of Stock [Line Items]                              
Measurement input                     0.45        
Risk-free rate of interest | June 9th Purchase Agreement                              
Class of Stock [Line Items]                              
Measurement input                     0.32        
Risk-free rate of interest | April 2020 public offering                              
Class of Stock [Line Items]                              
Measurement input         0.37                    
Risk-free rate of interest | Warrant [Member] | Lippert Heishorn Associates Inc [Member]                              
Class of Stock [Line Items]                              
Measurement input               1.88              
Risk-free rate of interest | Warrant [Member] | DFC Advisory Services, LLC [Member]                              
Class of Stock [Line Items]                              
Measurement input             1.51                
Risk-free rate of interest | Warrant [Member] | Walsh [Member]                              
Class of Stock [Line Items]                              
Measurement input                   2.38          
Risk-free rate of interest | Warrant [Member] | Alexander Capital, LP.                              
Class of Stock [Line Items]                              
Measurement input                 2.18 2.38          
Risk-free rate of interest | March 2020 Warrant                              
Class of Stock [Line Items]                              
Measurement input           0.38                  
Risk-free rate of interest | April 2020 Maxim Warrant                              
Class of Stock [Line Items]                              
Measurement input         0.37                    
Term (Years) | June 4th Purchase Agreement                              
Class of Stock [Line Items]                              
Measurement input                     5.5        
Term (Years) | June 9th Purchase Agreement                              
Class of Stock [Line Items]                              
Measurement input                     5.5        
Term (Years) | April 2020 public offering                              
Class of Stock [Line Items]                              
Measurement input         5                    
Term (Years) | Warrant [Member] | Lippert Heishorn Associates Inc [Member]                              
Class of Stock [Line Items]                              
Fair Value Expected Term               5 years              
Term (Years) | Warrant [Member] | DFC Advisory Services, LLC [Member]                              
Class of Stock [Line Items]                              
Fair Value Expected Term             5 years                
Term (Years) | Warrant [Member] | Walsh [Member]                              
Class of Stock [Line Items]                              
Fair Value Expected Term                   5 years          
Term (Years) | Warrant [Member] | Alexander Capital, LP.                              
Class of Stock [Line Items]                              
Fair Value Expected Term                 4 years 5 years          
Term (Years) | March 2020 Warrant                              
Class of Stock [Line Items]                              
Fair Value Expected Term           5 years                  
Term (Years) | April 2020 Maxim Warrant                              
Class of Stock [Line Items]                              
Measurement input         5