Stockholders' Equity (Details 1) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Stockholders Equity [Line Items]    
Outstanding Number of Options, at January 1, 2013 14,787,287  
Granted Number of Options 3,840,962  
Exercised Number of Options 0  
Forfeited/Expired Number of Options (51,042)  
Outstanding Number of Options, at December 31, 2013 18,577,207 14,787,287
Exercisable Number of Options, at December 31, 2013 12,659,353  
Vested and expected to vest Number of Options 18,577,207  
Outstanding Weighted-Average Exercise Price, at January 1, 2013 $ 1.98  
Granted Weighted-Average Exercise Price $ 1.11  
Exercised Weighted-Average Exercise Price $ 0  
Forfeited Weighted-Average Exercise Price $ 2.72  
Outstanding Weighted-Average Exercise Price, at December 31, 2013 $ 1.79 $ 1.98
Exercisable Weighted-Average Exercise Price, at December 31, 2013 $ 2.14  
Vested and expected to vest Weighted-Average Exercise Price $ 1.79  
Outstanding Weighted-Average Remaining Contractual Life (in Years) 5 years 9 months 18 days 6 years 1 month 6 days
Exercisable Weighted-Average Remaining Contractual Life (in Years), at December 31, 2013 4 years 6 months  
Vested and expected to vest Weighted-Average Remaining Contractual Life (in Years) 5 years 9 months 18 days  
Outstanding Aggregate Intrinsic Value, at January 1, 2013 $ 1,926,000  
Outstanding Aggregate Intrinsic Value, at December 31, 2013 24,000,710 1,926,000
Exercisable Aggregate Intrinsic Value, at December 31, 2013 12,938,385  
Vested and expected to vest Aggregate Intrinsic Value $ 24,000,710