Common Stock Reserved for Future Issuance (Details) - shares	Jun. 30, 2016	Dec. 31, 2015
Stockholders' equity
Shares reserved for future issuance (in shares)	3,493,157	2,799,213
Warrants for the purchase of Common Stock
Stockholders' equity
Shares reserved for future issuance (in shares)	24,566	59,405
Options to purchase Common stock
Stockholders' equity
Shares reserved for future issuance (in shares)	3,133,107	2,557,456
Employee Stock Purchase Plan
Stockholders' equity
Shares reserved for future issuance (in shares)	335,484	182,352