12.	Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding during the period and giving effect to all potentially dilutive common shares using the treasury-stock method. For purposes of this calculation, outstanding stock options and stock awards are considered to be potentially dilutive common shares and are only included in the calculation of diluted net loss per share when their effect is dilutive.

	December 31,
	2017			2016			2015
Basic and diluted net loss per share (in thousands, except per share amounts):
Numerator:
Net loss	$	(95,154	)	$	(112,444	)	$	(106,794	)
Denominator for basic and diluted net loss per share:
Weighted-average common shares outstanding		52,613			38,506			32,881
Basic and diluted net loss per share	$	(1.81	)	$	(2.92	)	$	(3.25	)

Outstanding stock options and stock awards were excluded from the calculation of net loss per share allocable to common stockholders as the effect of their inclusion would have been anti-dilutive.

	December 31,
	2017		2016		2015
Outstanding securities not included in diluted net loss per share calculation (in thousands):
Stock options and stock awards		5,981		4,673		3,086
Total		5,981		4,673		3,086