Net Loss Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net loss	$ (9,334)	$ (16,703)
Weighted average shares	62,189	57,620
Net loss per share - basic and diluted	$ (0.15)	$ (0.29)
Common stock options	7,817	8,435
Common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock options	2,768	3,748
Restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock options	492	487
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock options	457	0
Common stock issuable in connection with contingent payment
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Common stock options	4,100	4,200