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Stock Purchase Warrants (Details) - $ / shares
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Jul. 31, 2015
Sep. 17, 2014
Jul. 09, 2014
Assumptions used in calculating the estimated fair value of the warrants          
Closing stock price (in dollars per share)       $ 2.55  
December 2010 Warrants          
Stock Purchase Warrants          
Total shares issuable on exercise 15,405        
August 2013 warrants          
Stock Purchase Warrants          
Exercise price per share (in dollars per share) $ 4.80       $ 4.80
Total shares issuable on exercise 724,950   226,299   362,500
Assumptions used in calculating the estimated fair value of the warrants          
Closing stock price (in dollars per share) $ 2.58 $ 3.04      
Expected dividend rate 0.00% 0.00%      
Expected stock price volatility 91.37% 83.20%      
Risk-free interest rate 1.31% 1.20%      
Expected life 2 years 7 months 17 days 3 years 7 months 17 days