Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2017

Earnings Per Share [Abstract]

Schedule of reconciliation of numerator and denominator used in calculation of basic and diluted net loss per share

A reconciliation of the numerator and denominator used in the calculation of the basic and diluted net loss per share is as follows (in thousands, except per share data):

	December 31,
	2017			2016			2015
Historical net loss per share
Numerator:
Net loss, basic and diluted	$	(89,490	)	$	(60,058	)	$	(51,802	)
Denominator:
Weighted average common shares outstanding, basic and diluted	22,558			21,711			18,116
Less: weighted average unvested common shares subject to repurchase	—			—			(5		)
Weighted average common shares used in calculating net loss per share, basic and diluted	22,558			21,711			18,111
Net loss per share, basic and diluted	$	(3.97	)	$	(2.77	)	$	(2.86	)

Schedule of outstanding shares of potentially dilutive securities excluded from the computation of diluted net loss per share of common stock, because including them would have been anti-dilutive

The following shares of potentially dilutive securities were excluded from the computation of diluted net loss per share for the periods presented, because including them would have been anti-dilutive (in thousands):

	December 31,
	2017	2016	2015
Options to purchase common stock	5,940	5,523	5,249
Total	5,940	5,523	5,249