Net Loss Per Share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Antidilutive Common Stock Equivalents Excluded from Computation of Diluted Net Loss Per Share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	1,593,606	9,256,898	1,593,606	9,256,898
Convertible preferred stock
Antidilutive Common Stock Equivalents Excluded from Computation of Diluted Net Loss Per Share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)		8,012,987		8,012,987
Options to purchase Common Stock
Antidilutive Common Stock Equivalents Excluded from Computation of Diluted Net Loss Per Share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	1,534,201	1,209,072	1,534,201	1,209,072
Warrants for the purchase of Common Stock
Antidilutive Common Stock Equivalents Excluded from Computation of Diluted Net Loss Per Share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	59,405	34,839	59,405	34,839