Annual report pursuant to Section 13 and 15(d)

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

v3.7.0.1
Stock options and warrants (Schedule of Nonvested Awards) (Details) - Stock Incentive Plan [Member] - $ / shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Nonvested Shares Underlying Options    
Beginning balance 33,336  
Granted 259,666 136,813
Vested (191,644)  
Forfeited (3,620) (28,205)
Ending balance 97,738 33,336
Weighted Average Exercise Price    
Beginning balance $ 15.54  
Granted 2.90 $ 15.12
Vested 4.56  
Forfeited 15.13 16.48
Ending balance 3.51 15.54
Weighted Average Grant Date Fair Value    
Beginning balance 11.41  
Granted 2.15  
Vested 3.37  
Forfeited 10.75  
Ending balance $ 2.58 $ 11.41