Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016

Computation of Basic and Diluted Net Loss per Share

The following table sets forth the reconciliation of the numerator and denominator used in the computation of basic and diluted net loss per share for the years ended December 31, 2016, 2015 and 2014 (in thousands, except per share amounts):

	Year Ended December 31,
	2016			2015			2014
Numerator for Basic and Diluted:
Net loss used for basic calculation	$	(62,906	)	$	(55,868	)	$	(38,755	)
Effect of revaluation of warrant liability		—			(3,566	)		(7,708	)
Adjusted net loss used for dilution calculation	$	(62,906	)	$	(59,434	)	$	(46,463	)
Denominator:
Basic weighted average number of shares outstanding		101,826			96,068			74,767
Effect of dilutive potential shares		—			837			1,767
Diluted weighted average number of shares outstanding		101,826			96,905			76,534
Net loss per share:
Basic	$	(0.62	)	$	(0.58	)	$	(0.52	)
Diluted		(0.62	)		(0.61	)		(0.61	)

Anti-Dilutive Effect of Common Shares

The table below presents shares underlying stock options and restricted stock units that were excluded from the calculation of the weighted average number of shares outstanding used for the calculation of diluted net loss per share. These are excluded from the calculation due to their anti-dilutive effect for the years ended December 31, 2016, 2015 and 2014 (shares in thousands):

	Year Ended December 31,
	2016		2015		2014
Weighted average number of anti-dilutive potential shares:
Stock options		15,592		13,681		11,722
Restricted stock units		576		—		—
Total		16,168		13,681		11,722