Quarterly report pursuant to Section 13 or 15(d)

Capitalization and Equity Structure - Valuation Assumptions (Details)

v3.20.1
Capitalization and Equity Structure - Valuation Assumptions (Details)
 3 Months Ended 12 Months Ended
Mar. 31, 2020
$ / shares
Dec. 31, 2019
$ / shares
Dec. 31, 2016
$ / shares
Schedule of Capitalization, Equity [Line Items]      
Current share price (in dollars per share)     $ 120.00
December 2019 Warrants | Current share price      
Schedule of Capitalization, Equity [Line Items]      
Current share price (in dollars per share) $ 2.83 $ 5.86  
December 2019 Warrants | Conversion price      
Schedule of Capitalization, Equity [Line Items]      
Conversion price (in dollars per share) $ 8.10 $ 8.10  
December 2019 Warrants | Risk-free interest rate      
Schedule of Capitalization, Equity [Line Items]      
Measurement input percentage 0.0041 0.0173  
December 2019 Warrants | Expected term (years)      
Schedule of Capitalization, Equity [Line Items]      
Term (years) 5 years 2 months 12 days 5 years 6 months  
December 2019 Warrants | Volatility of stock      
Schedule of Capitalization, Equity [Line Items]      
Measurement input percentage 0.9526 0.957  
December 2019 Placement Agent Warrants | Current share price      
Schedule of Capitalization, Equity [Line Items]      
Current share price (in dollars per share) $ 2.83 $ 5.86  
December 2019 Placement Agent Warrants | Conversion price      
Schedule of Capitalization, Equity [Line Items]      
Conversion price (in dollars per share) $ 8.44 $ 8.44  
December 2019 Placement Agent Warrants | Risk-free interest rate      
Schedule of Capitalization, Equity [Line Items]      
Measurement input percentage 0.0037 0.0169  
December 2019 Placement Agent Warrants | Expected term (years)      
Schedule of Capitalization, Equity [Line Items]      
Term (years) 4 years 8 months 12 days 5 years  
December 2019 Placement Agent Warrants | Volatility of stock      
Schedule of Capitalization, Equity [Line Items]      
Measurement input percentage 0.9579 0.931  
May 2019 Warrants | Current share price      
Schedule of Capitalization, Equity [Line Items]      
Current share price (in dollars per share) $ 2.83 $ 5.86  
May 2019 Warrants | Conversion price      
Schedule of Capitalization, Equity [Line Items]      
Conversion price (in dollars per share) $ 5.70 $ 5.70  
May 2019 Warrants | Risk-free interest rate      
Schedule of Capitalization, Equity [Line Items]      
Measurement input percentage 0.0034 0.0167  
May 2019 Warrants | Expected term (years)      
Schedule of Capitalization, Equity [Line Items]      
Term (years) 4 years 2 months 12 days 4 years 4 months 24 days  
May 2019 Warrants | Volatility of stock      
Schedule of Capitalization, Equity [Line Items]      
Measurement input percentage 0.993 0.939  
2015 Warrants | Current share price      
Schedule of Capitalization, Equity [Line Items]      
Current share price (in dollars per share) $ 2.83 $ 5.86  
2015 Warrants | Conversion price      
Schedule of Capitalization, Equity [Line Items]      
Conversion price (in dollars per share) $ 41.25 $ 41.25  
2015 Warrants | Risk-free interest rate      
Schedule of Capitalization, Equity [Line Items]      
Measurement input percentage 0.0016 0.0159  
2015 Warrants | Expected term (years)      
Schedule of Capitalization, Equity [Line Items]      
Term (years) 9 months 11 months 26 days  
2015 Warrants | Volatility of stock      
Schedule of Capitalization, Equity [Line Items]      
Measurement input percentage 1.0345 0.9846