Stockholders' Equity - Summary of Reserved Shares of Common Stock for Future Issuance (Details) - shares	Jun. 30, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	3,617,179	3,075,500
Options to purchase common stock
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	1,975,620	1,526,346
Shares available for future issuance
Class of Stock [Line Items]
Common stock, shares reserved for future issuance	1,641,559	1,549,154