Stockholders' Equity and Redeemable Convertible Preferred Stock (Details 2) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Minimum [Member]
Exercise price	$ 0.22	$ 1.34	$ 0.22	$ 1.34
Expected stock price volatility	117.20%	77.70%	117.20%	77.70%
Risk-free rate of interest	0.74%	0.95%	0.74%	0.76%
Term (years)	1 year 10 months 24 days	2 years 6 months	1 year 10 months 24 days	2 years 6 months
Maximum [Member]
Exercise price	$ 1.73	$ 1.79	$ 1.73	$ 1.79
Expected stock price volatility	130.40%	79.00%	130.40%	90.60%
Risk-free rate of interest	1.08%	1.76%	1.08%	1.76%
Term (years)	3 years	5 years 3 months 18 days	3 years	5 years 6 months