Quarterly report pursuant to Section 13 or 15(d)

Fair value measurements (Schedule of Changes in Level 3 Liabilities Measured at Fair Value) (Details)

v3.19.2
Fair value measurements (Schedule of Changes in Level 3 Liabilities Measured at Fair Value) (Details) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2019
Mar. 31, 2019
Jun. 30, 2019
Jun. 30, 2018
Conversion of convertible notes to common stock $ (10,225,959)   $ (10,225,959)  
Recalssification of warrant liability to equity     5,438,660
Convertible Notes [Member] | Fair Value, Inputs, Level 3 [Member]        
Issuance of senior secured convertible notes   $ 6,330,726    
Issuance of warrants in connection with convertible notes      
Balance Beginning 7,975,907 6,330,726 6,330,726  
Change in fair value 2,250,651 1,644,582    
Conversion of convertible notes to common stock (10,225,959)      
Recalssification of warrant liability to equity      
Balance Ending 7,975,907  
Warrant [Member] | Fair Value, Inputs, Level 3 [Member]        
Issuance of senior secured convertible notes      
Issuance of warrants in connection with convertible notes   2,568,934    
Balance Beginning 5,322,162 2,568,934 2,568,934  
Change in fair value 116,498 2,753,228    
Conversion of convertible notes to common stock      
Recalssification of warrant liability to equity (5,438,660)      
Balance Ending $ 5,322,162