Net Loss Per Share of Common Stock - Antidilutive Securities (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Securities excluded from the calculation of weighted average common shares outstanding
Total anti-dilutive securities (shares)	9,470,657	10,103,336	9,470,657	10,103,336
Stock option awards
Securities excluded from the calculation of weighted average common shares outstanding
Total anti-dilutive securities (shares)	2,482,505	5,738,480	2,482,505	5,738,480
Restricted stock unit awards
Securities excluded from the calculation of weighted average common shares outstanding
Total anti-dilutive securities (shares)	6,988,152	4,364,856	6,988,152	4,364,856