Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Warrant activities (Details)

v3.19.3
Stockholders' Equity - Warrant activities (Details) - Warrants [Member] - USD ($)
9 Months Ended 12 Months Ended
Sep. 30, 2019
Dec. 31, 2018
Subsidiary or Equity Method Investee [Line Items]    
Number of shares, Outstanding 2,754,189  
Number of shares, Granted 60,000  
Number of shares, Forfeited (73,009)  
Number of shares, Outstanding 2,741,180 2,754,189
Number of shares, Exercisable 776,180  
Weighted average exercise price, Outstanding $ 3.28  
Weighted average exercise price, Granted 1.92  
Weighted average exercise price, Forfeited 5.65  
Weighted average exercise price, Outstanding 3.19 $ 3.28
Weighted average exercise price, Exercisable $ 3.76  
Total intrinsic value, Outstanding $ 2,400 $ 7,800
Total intrinsic value, Exercisable $ 2,400  
Weighted average remaining contractual life (years), Outstanding 2 years 11 months 23 days 3 years 5 months 27 days
Weighted average remaining contractual life, Exercisable (years) 2 years 7 months 13 days