Net Loss Per Share (Tables)

3 Months Ended

Mar. 31, 2013

Net Loss Per Share [Abstract]

Antidilutive Securities Excluded

The following number of shares outstanding, prior to the application of the treasury stock method, were excluded from the computation of diluted net loss per common share for the periods presented because including them would have had an anti-dilutive effect (in thousands):

	Three Months Ended
	March 31,
	2013		2012
Options to purchase common stock		3,738		3,664
Restricted stock units		149		55
Employee stock purchase plan shares		32		25
Total		3,919		3,744