Net Loss Per Share - Schedule of Securities Excluded from Calculation of Net (Loss) per Share (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive excluded from computation of earnings per share amount (shares)	6,465,109	9,442,022	13,896,550
Common Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive excluded from computation of earnings per share amount (shares)	0	138,277	0
Common Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive excluded from computation of earnings per share amount (shares)	4,407,765	3,668,662	1,294,594
Restricted Stock Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive excluded from computation of earnings per share amount (shares)	1,802,130	1,562,918	2,147,157
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive excluded from computation of earnings per share amount (shares)	255,214	217,206	0
2018 Convertible Notes [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive excluded from computation of earnings per share amount (shares)	0	3,854,959	10,454,799