Annual report pursuant to Section 13 and 15(d)

Stock options, warrants and restricted common stock (Other Common Stock Purchase Warrants) (Narrative) (Details)

v3.19.1
Stock options, warrants and restricted common stock (Other Common Stock Purchase Warrants) (Narrative) (Details) - USD ($)
 1 Months Ended 12 Months Ended
Feb. 14, 2018
Mar. 31, 2018
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Share-based compensation, operating expense     $ 4,660,406 $ 2,589,812  
Proceeds from issuance of common stock     38,451,052  
Proceeds from warrants exercised     $ 350,000 1,860,000  
Common Stock [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Proceeds from warrants exercised $ 350,000        
Common shares issued 100,000 100,000 3,215    
Warrant [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Options forfeited     160,773    
Proceeds from warrants exercised     $ 350,000    
Number of warrants exercised     13,009    
Private Placement [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Proceeds from issuance of common stock       $ 1,000,000  
Expiration date       Dec. 31, 2020  
Common shares issued       400,000  
Nonqualified [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Awards outstanding     1,671,113 1,944,895 527,003
Options granted     4,451,113  
Options granted, exercise price     $ 17.03  
Options forfeited       169,074  
Lapsed shares       60,000  
Number of lapsed options vested       15,000  
Number of lapsed options unvested       45,000  
Expired options       71,574  
Remaining forfeited options       37,500  
Proceeds from warrants exercised       $ 1,860,000  
Number of warrants exercised       620,000  
Warrants issued price per share       $ 3.00  
Number of common shares hold by warrant holders       2,244,147  
Shares issued of common stock in exchange for termination of warrants       1,335,408  
Nonqualified [Member] | May 2013 private offering [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Exercise price       $ 10.88  
Shares surrendered for issuance of common stock       184,147  
Common shares issued       106,719  
Nonqualified [Member] | March 2017 private offering [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Exercise price       $ 3.50  
Shares surrendered for issuance of common stock       360,000  
Common shares issued       214,851  
Nonqualified [Member] | March 2017 private offering of convertible notes [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares surrendered for issuance of common stock       1,700,000  
Common shares issued       1,013,838  
Nonqualified [Member] | Compensatory Arrangements [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Exercise price     $ 3.78    
Stock Incentive Plan [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Awards outstanding     62,000 119,533 566,747
Options granted     62,000 120,000  
Options granted, exercise price     $ 15.71 $ 9.00  
Share-based compensation, operating expense     $ 58,000    
Stock Incentive Plan [Member] | March 2017 private offering of convertible notes [Member]          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Exercise price       $ 3.56