Stockholders' Equity - Amended and Restated Certificate of Incorporation (Details 2)	May. 29, 2014 class shares	May. 29, 2014 series class shares	May. 07, 2014 USD ($)	Dec. 31, 2015 shares	Dec. 31, 2014 shares
Sale of stock
Number of shares of common stock authorized | shares	150,000,000	150,000,000		150,000,000	150,000,000
Authorized shares of preferred stock | shares	10,000,000	10,000,000
Number of classes of Board | class	3
Term of Board member		3 years
Number of classes elected at each annual meeting | class		1
Minimum
Sale of stock
Number of series of preferred stock that may be issued | series		1
Affirmative vote of all then-outstanding shares of capital stock for removal of directors (as a percent)		75.00%
Series C Convertible Preferred Stock | Automatic conversion, underwritten public offering | Minimum
Sale of stock
Gross proceeds from sale of common stock			$ 45,000,000
Series B Convertible Preferred Stock | Automatic conversion, underwritten public offering | Minimum
Sale of stock
Gross proceeds from sale of common stock			45,000,000
Series A-1 Convertible Preferred Stock | Automatic conversion, underwritten public offering | Minimum
Sale of stock
Gross proceeds from sale of common stock			45,000,000
Series A-2 Convertible Preferred Stock | Automatic conversion, underwritten public offering | Minimum
Sale of stock
Gross proceeds from sale of common stock			$ 45,000,000