Quarterly report pursuant to Section 13 or 15(d)

Stock options and warrants (Schedule of Nonvested Awards) (Details)

v3.5.0.2
Stock options and warrants (Schedule of Nonvested Awards) (Details) - Stock Incentive Plan [Member] - $ / shares
6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Nonvested Shares Underlying Options    
Beginning balance 33,336  
Granted 227,000  
Vested (54,028)  
Forfeited (3,620) (20,614)
Ending balance 202,688  
Weighted Average Exercise Price    
Beginning balance $ 15.54  
Granted 2.89  
Vested 6.67  
Forfeited 15.13 $ 16.48
Ending balance 3.75  
Weighted Average Grant Date Fair Value    
Beginning balance 11.41  
Granted 2.13  
Vested 5.02  
Forfeited 10.75  
Ending balance $ 2.73