Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Summary of Basic and Diluted Net Loss Per Share of Common Stock

The following table summarizes the computation of basic and diluted net loss per share of our common stock for 2018, 2017 and 2016:

	Year Ended December 31,
	2018			2017			2016
	(in thousands, except share and per share data)
Numerator:
Net loss	$	(55,545	)	$	(45,470	)	$	(49,000	)
Denominator:
Weighted-average common shares outstanding, basic and diluted	46,456,825			42,952,950			41,248,473
Net loss per share, basic and diluted	$	(1.20	)	$	(1.06	)	$	(1.19	)

Anti-Dilutive Securities Excluded from Computation Diluted Weighted Average Shares Outstanding

The following potentially dilutive securities outstanding, prior to the use of the treasury stock method or if-converted method, have been excluded from the computation of diluted weighted-average shares outstanding for the respective periods below because they would have been anti-dilutive:

	Year Ended December 31,
	2018	2017	2016
Options to purchase common stock	3,713,179	4,684,954	4,580,375
Unvested restricted stock	21,677	210,083	585,004
Unvested restricted stock units	2,773,773	1,988,509	734,577
Shares to be issued under ESPP	74,634	79,551	91,815
Total	6,583,263	6,963,097	5,991,771