Fair Value Measurements - Assumptions used to record the fair value of the warrants (Details) - Valuation Technique, Option Pricing Model	Dec. 31, 2019	Dec. 31, 2018
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and rights outstanding, measurement input	0.0175	0.0169
Expected life (in years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and rights outstanding, term	5 years	4 years 11 months 23 days
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and rights outstanding, measurement input	0.8729	0.8774