Significant Accounting Policies, Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings (loss) per share [Abstract]
Net loss	$ (6,026)	$ (15,609)	$ (10,338)	$ (18,040)
Basic [Abstract]
Weighted-average shares of common stock outstanding (in shares)	55,120	54,441	55,003	54,380
Shares used in computing basic loss per share (in shares)	55,120	54,441	55,003	54,380
Basic loss per share (in dollars per share)	$ (0.11)	$ (0.29)	$ (0.19)	$ (0.33)
Diluted [Abstract]
Weighted-average shares of common stock outstanding (in shares)	55,120	54,441	55,003	54,380
Add: Common equivalent shares outstanding (in shares)	0	0	0	0
Shares used in computing diluted loss per share (in shares)	55,120	54,441	55,003	54,380
Diluted loss per share (in dollars per share)	$ (0.11)	$ (0.29)	$ (0.19)	$ (0.33)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares outstanding excluded from computation of diluted loss per share (in shares)			6,498	6,076
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares outstanding excluded from computation of diluted loss per share (in shares)			4,770	3,738
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares outstanding excluded from computation of diluted loss per share (in shares)			1,238	1,848
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares outstanding excluded from computation of diluted loss per share (in shares)			490	490