Net Loss per Share (Tables)

3 Months Ended

Mar. 31, 2013

Earnings Per Share [Abstract]

Reconciliation of Number of Shares Used in Calculation of Basic and Diluted Net Loss Per Share

A reconciliation of the number of shares used in the calculation of basic and diluted net loss per share is as follows (in thousands):

	Three Months Ended March 31,
	2013		2012
Weighted-average shares of common stock outstanding		28,024		15,901
Less: weighted-average number of unvested restricted common shares outstanding		—		58
Weighted-average number of common shares used in calculating net loss per common share		28,024		15,843

Potentially Dilutive Common Stock Equivalent Shares Excluded from Computation of Weighted-Average Shares Outstanding

The following potentially dilutive common stock equivalent shares have been excluded from the computation of the weighted-average shares outstanding as their effect would have been anti-dilutive (in thousands):

	Three Months Ended March 31,
	2013		2012
Redeemable convertible preferred stock		—		8,696
Options outstanding		3,401		3,971
Restricted stock units outstanding		1,419		—
Unvested restricted shares		—		58
Warrants		28		47
Total		4,848		12,772