Net Income (Loss) Per Share - Computation of Basic and Diluted Net Income (Loss) Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income (loss)	$ (7,566)	$ 520	$ (18,792)	$ (8,638)
Denominator (basic):
Weighted average number of shares outstanding, basic (in shares)	92,385,195	94,592,297	93,566,920	94,314,192
Denominator (diluted):
Weighted average number of shares outstanding, basic (in shares)	92,385,195	94,592,297	93,566,920	94,314,192
Dilutive stock options outstanding (in shares)	0	3,050,106	0	0
Dilutive restricted stock units and awards (in shares)	0	411,066	0	0
Dilutive shares purchased under ESPP (in shares)	0	7,017	0	0
Weighted average common shares from warrants (in shares)	0	2,228,386	0	0
Weighted average number of shares outstanding, diluted (in shares)	92,385,195	100,288,872	93,566,920	94,314,192
Earnings per share, basic (in dollars per share)	$ (0.08)	$ 0.01	$ (0.20)	$ (0.09)
Earnings per share, diluted (in dollars per share)	$ (0.08)	$ 0.01	$ (0.20)	$ (0.09)