Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2013

Computation of Basic and Diluted Net Loss per Common Share

The following table sets forth the reconciliation of the numerator and denominator used in the computation of basic and diluted net loss per common share for the three and nine months ended September 30, 2013, and 2012 (in thousands, except per share amounts):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2013			2012			2013			2012
Numerator:
Net loss used for basic calculation	$	(20,501	)	$	(3,460	)	$	(37,477	)	$	(14,201	)
Effect of revaluation of warrant liability		—			(873	)		—			—
Adjusted net loss used for diluted calculation	$	(20,501	)	$	(4,333	)	$	(37,477	)	$	(14,201	)
Denominator:
Basic weighted average number of common shares outstanding		69,791			54,875			66,464			54,130
Effect of dilutive potential common shares resulting from warrants		—			502			—			—
Diluted weighted average number of common shares outstanding		69,791			55,377			66,464			54,130
Net loss per common share:
Basic	$	(0.29	)	$	(0.06	)	$	(0.56	)	$	(0.26	)
Diluted	$	(0.29	)	$	(0.08	)	$	(0.56	)	$	(0.26	)

Anti-Dilutive Effect of Common Shares

The table below presents common shares underlying stock options, convertible preferred stock, employee stock purchase plan rights, warrants and restricted stock units that are excluded from the calculation of the weighted average number of common shares outstanding used for the calculation of diluted net loss per common share. These are excluded from the calculation due to their anti-dilutive effect for the three and nine months ended September 30, 2013, and 2012 (shares in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2013		2012		2013		2012
Anti-dilutive common shares		16,651		8,704		16,301		14,813