Quarterly report pursuant to Section 13 or 15(d)

Capitalization and Equity Structure - Warrants (Details)

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Capitalization and Equity Structure - Warrants (Details) - $ / shares
shares in Thousands
 1 Months Ended 2 Months Ended 3 Months Ended 12 Months Ended
Jun. 30, 2020
Dec. 31, 2019
Feb. 28, 2021
Mar. 31, 2021
Dec. 31, 2020
May 31, 2019
Class Of Warrant Or Right, Outstanding [Roll Forward]            
Beginning balance (in shares)     1,325 1,325    
Warrants issued (in shares)       0    
Expired (in shares)       358    
Ending balance (in shares)       1,240 1,325  
2021 Warrants            
Schedule of Capitalization, Equity [Line Items]            
Exercise price (in dollars per share)     $ 12.81 $ 12.81    
Term (Years)     5 years 5 years    
Class Of Warrant Or Right, Outstanding [Roll Forward]            
Beginning balance (in shares)     0 0    
Warrants issued (in shares)     273 273    
Expired (in shares)       0    
Ending balance (in shares)       273 0  
June 2020 Investor Warrants            
Schedule of Capitalization, Equity [Line Items]            
Exercise price (in dollars per share) $ 5.18     $ 5.18    
Term (Years)       5 years 6 months    
Class Of Warrant Or Right, Outstanding [Roll Forward]            
Beginning balance (in shares)     397 397    
Warrants issued (in shares)       0    
Expired (in shares)       270 477  
Ending balance (in shares) 874     127 397  
June 2020 Placement Agent Warrants            
Schedule of Capitalization, Equity [Line Items]            
Exercise price (in dollars per share)       $ 5.64    
Term (Years)       5 years    
Class Of Warrant Or Right, Outstanding [Roll Forward]            
Beginning balance (in shares)     122 122    
Warrants issued (in shares) 122     0    
Expired (in shares)       83    
Ending balance (in shares)       39 122  
December 2019 Warrants            
Schedule of Capitalization, Equity [Line Items]            
Exercise price (in dollars per share)   $ 8.10   $ 8.10    
Term (Years)   5 years   5 years    
Class Of Warrant Or Right, Outstanding [Roll Forward]            
Beginning balance (in shares)         556  
Warrants issued (in shares)       0    
Expired (in shares)       0    
Ending balance (in shares)   556   556    
December 2019 Placement Agent Warrants            
Schedule of Capitalization, Equity [Line Items]            
Exercise price (in dollars per share)   $ 8.44   $ 8.44    
Term (Years)       5 years    
Class Of Warrant Or Right, Outstanding [Roll Forward]            
Beginning balance (in shares)     52 52 52  
Warrants issued (in shares)       0    
Expired (in shares)       0    
Ending balance (in shares)   52   52 52  
May 2019 Warrants            
Schedule of Capitalization, Equity [Line Items]            
Exercise price (in dollars per share) $ 3.52     $ 3.52   $ 3.52
Term (Years)       5 years    
Class Of Warrant Or Right, Outstanding [Roll Forward]            
Beginning balance (in shares)     198 198    
Warrants issued (in shares)       0    
Expired (in shares)       5 246  
Ending balance (in shares)       193 198