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	Dec. 31, 2014	Dec. 10, 2013
Earnings Per Share, Basic and Diluted [Abstract]
Net loss	$ (13,001)	$ (8,993)	$ (24,215)	$ (3,698)
Shares used in computing basic and diluted net loss per share	67,615	62,699	67,441	62,403
Basic and diluted net loss per share	$ (0.19)	$ (0.14)	$ (0.36)	$ (0.06)
Securities Excluded from Calculations of Earnings Per Share Because Impact Would Have Been Anti-Dilutive [Abstract]
Outstanding securities used in calculations	2,220	2,376	2,206	2,541
Convertible notes	$ 72,156		$ 72,156		$ 70,407
Potential Dilutive Effect of Securities [Abstract]
Conversion of the Notes	3,588	3,588	3,588	3,588
Convertible Debt
Securities Excluded from Calculations of Earnings Per Share Because Impact Would Have Been Anti-Dilutive [Abstract]
Convertible notes						$ 86,300
Stated interest rate					2.25%
Common stock options
Securities Excluded from Calculations of Earnings Per Share Because Impact Would Have Been Anti-Dilutive [Abstract]
Outstanding securities used in calculations	1,812	1,813	1,812	1,917
Restricted stock awards
Securities Excluded from Calculations of Earnings Per Share Because Impact Would Have Been Anti-Dilutive [Abstract]
Outstanding securities used in calculations	139	420	137	422
Restricted stock units
Securities Excluded from Calculations of Earnings Per Share Because Impact Would Have Been Anti-Dilutive [Abstract]
Outstanding securities used in calculations	269	143	257	202