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Warrant Liabilities (Tables)
 12 Months Ended
Dec. 31, 2017
Warrant Liabilities [Abstract]  
Schedule of Weighted-Average Assumptions
The following reflects the weighted-average assumptions for each of the periods indicated:
 
  
Year Ended December 31,
 
  
2017
  
2016
  
2015
 
          
Risk-free interest rate
  
1.53
%
  
0.90
%
  
0.57
%
Expected dividend yield
  
0
%
  
0
%
  
0
%
Expected lives
  
0.55
   
1.23
   
0.59
 
  Expected volatility
  
96.7
%
  
119.1
%
  
61.7
%
Number of warrants classified as liabilities
  
2,834,246
   
4,752,512
   
1,061,976
 
Gain on warrant liabilities
 
$
1,367,777
  
$
3,827,617
  
$
4,437,628