Basic and Diluted Net Loss Per Share - Schedule of Common Equivalent Shares were Excluded From Diluted Net Loss Per Share Calculation because their Inclusion would have been Anti-Dilutive (Details) - shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss per share	6,796,608	2,106,111
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss per share	2,717,533	2,106,111
Convertible Senior Notes
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss per share	3,411,199
Non-vested Market-Based Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss per share	222,626
Non-vested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss per share	445,250