Annual report pursuant to Section 13 and 15(d)

Stock options, warrants and restricted common stock (Schedule of Restricted Stock Activity) (Details)

v3.19.1
Stock options, warrants and restricted common stock (Schedule of Restricted Stock Activity) (Details) - Restricted common stock [Member] - $ / shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Number of shares    
Beginning balance 496,152
Granted 431,000 863,000
Vested (530,065) (326,848)
Forfeited (301,148) (40,000)
Ending balance 95,939 496,152
Weighted Average Grant Date Fair value    
Beginning balance $ 5.97
Granted 10.46 5.39
Vested 7.61 4.87
Forfeited 7.68 3.13
Ending balance $ 12.49 $ 5.97