Summary of Significant Accounting Policies - Net Loss Per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
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)	2,510,975	1,771,416	2,510,975	1,771,416
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)	2,486,409	1,712,011	2,486,409	1,712,011
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)	24,566	59,405	24,566	59,405