Net Income (Loss) Per Share - (Basic and Diluted Net Income 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 Per Share [Abstract]
Net (loss) income	$ (1,159)	$ 8,751	$ (1,537)	$ 15,069
Weighted-average shares outstanding — basic (in shares)	35,987	36,120	35,864	36,072
Effect of dilutive securities from stock award plans (in shares)	0	910	0	915
Weighted-average shares outstanding — diluted (in shares)	35,987	37,030	35,864	36,987
Net (loss) income per share — basic (in dollars per share)	$ (0.03)	$ 0.24	$ (0.04)	$ 0.42
Net (loss) income per share — diluted (in dollars per share)	$ (0.03)	$ 0.24	$ (0.04)	$ 0.41
Anti-dilutive weighted-average shares related to stock award plans (in shares)	1,961	377	2,037	0