Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Income (Loss) (Numerator) [Abstract]
Net loss basic and diluted	$ (11,697)	$ (11,073)	$ (21,951)	$ (20,386)
Weighted Average Common Shares (Denominator) Abstract
Shares outstanding, basic and diluted (in shares)	69,647	69,561	69,642	66,775
Per share amount [Abstract]
Net loss per share, basic and diluted (in dollars per share)	$ (0.17)	$ (0.16)	$ (0.32)	$ (0.31)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted Average Number (in shares)	9,730	10,608	9,449	9,791
Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted Average Number (in shares)	6,705	6,261	6,483	6,066
Weighted Average Exercise Price (in dollars per share)	$ 9.80	$ 10.14	$ 9.93	$ 10.43
Contingent Consideration Liability [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted Average Number (in shares)	3,025	4,347	2,966	3,725