Quarterly report pursuant to Section 13 or 15(d)

Stockholders' equity (Details)

v3.19.2
Stockholders' equity (Details) - USD ($)
6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Class of Stock [Line Items]    
Proceeds from the sale of stock $ 19,671,712
Restricted Stock [Member]    
Class of Stock [Line Items]    
Issuance of common stock 106,251  
Restricted Stock [Member] | Director [Member]    
Class of Stock [Line Items]    
Issuance of common stock 93,751  
Restricted Stock [Member] | Consultant [Member]    
Class of Stock [Line Items]    
Issuance of common stock 12,500  
Series B Preferred Stock [Member]    
Class of Stock [Line Items]    
Preferred stock converted into common shares 8,001  
Series B Preferred Stock [Member] | H.C. Wainwright [Member]    
Class of Stock [Line Items]    
Maximum amount of sales shares $ 100,000,000  
Proceeds from the sale of stock $ 18,900,000  
Percentage of commission 3.00%  
Weighted average price $ 3.26