Quarterly report pursuant to Section 13 or 15(d)

Fair value of financial instruments (Details)

v3.19.3
Fair value of financial instruments (Details) - Fair Value, Measurements, Recurring [Member]
12 Months Ended
Dec. 31, 2018
USD ($)
Valuation Technique, Option Pricing Model [Member] | Notes Receivable [Member]  
Warrants And Rights Outstanding Measurement Inputs Monte Carlo Simulation
Fair Value, Inputs, Level 3 | Notes Receivable [Member]  
Assets, Fair Value $ 837,317
Investment in Warrants [Member] | Valuation Technique, Option Pricing Model [Member]  
Warrants And Rights Outstanding Measurement Inputs Black-Scholes Option Pricing Model
Investment in Warrants [Member] | Fair Value, Inputs, Level 3  
Assets, Fair Value $ 67,000
Measurement Input, Price Volatility [Member] | Notes Receivable [Member]  
Warrants And Rights Outstanding Measurement Inputs Probability of conversion and interest rates on comparable financial instruments
Measurement Input, Price Volatility [Member] | Investment in Warrants [Member]  
Warrants And Rights Outstanding Measurement Inputs Common stock volatility and discount