Stockholders' Equity - Schedule of Shares of Common Stock Reserved for Future Issuance (Details)	Mar. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	4,104,447	3,336,378
Employee Stock [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	324,008	155,220
Stock Options Outstanding [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	2,308,886	1,907,091
Future Stock Grants [Member]
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	1,471,553	1,274,067