Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.2
Fair Value Measurements - Contingently Issuable Warrants with option pricing model (Details) - Caelum Warrant Liabilities [Member]
12 Months Ended
Dec. 31, 2018
Measurement Input, Risk Free Interest Rate [Member] | Minimum [Member]  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Risk-free interest rate 2.905%
Measurement Input, Risk Free Interest Rate [Member] | Maximum [Member]  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Risk-free interest rate 2.909%
Measurement Input, Expected Dividend Rate [Member]  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Expected dividend yield 0.00%
Measurement Input, Expected Term [Member] | Minimum [Member]  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Expected term in years 3 years 10 months 2 days
Measurement Input, Expected Term [Member] | Maximum [Member]  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Expected term in years 3 years 11 months 16 days
Measurement Input, Price Volatility [Member]  
Fair Value Measurement Inputs and Valuation Techniques [Line Items]  
Expected volatility 70.00%