Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Contingently Issuable Warrants with option pricing model (Details)

v3.20.1
Fair Value Measurements - Contingently Issuable Warrants with option pricing model (Details)
3 Months Ended 12 Months Ended
Mar. 31, 2020
Dec. 31, 2019
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Probability of issuance of the warrant 10.00% 5.00%
Caelum Warrant Liabilities [Member] | Measurement Input, Risk Free Interest Rate [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Risk-free interest rate 0.70% 1.92%
Caelum Warrant Liabilities [Member] | Measurement Input, Expected Dividend Rate [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Expected dividend yield 0.00% 0.00%
Caelum Warrant Liabilities [Member] | Measurement Input, Expected Term [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Expected term in years 10 years 10 years
Caelum Warrant Liabilities [Member] | Measurement Input, Price Volatility [Member]    
Fair Value Measurement Inputs and Valuation Techniques [Line Items]    
Expected volatility 93.00% 93.00%