Net (Loss) Income Per Share - Antidilutive Securities (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock equivalents excluded from calculation of diluted net (loss) income per share (in shares)	13,825,984	2,900,906	13,825,984	2,900,906
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock equivalents excluded from calculation of diluted net (loss) income per share (in shares)	4,568,352	1,965,206	4,568,352	1,965,206
Unvested restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock equivalents excluded from calculation of diluted net (loss) income per share (in shares)	0	8,860	0	8,860
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock equivalents excluded from calculation of diluted net (loss) income per share (in shares)	9,257,632	926,840	9,257,632	926,840