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		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Abstract]
Net income	$ 1,983	$ 8,036	$ 446	$ 23,105
Weighted-average shares outstanding — basic (in shares)	36,332	35,806	36,020	35,983
Effect of dilutive securities from stock award plans (in shares)	747	807	675	887
Weighted-average shares outstanding — diluted (in shares)	37,079	36,613	36,695	36,870
Net (loss) income per share — basic (in dollars per share)	$ 0.05	$ 0.22	$ 0.01	$ 0.64
Net (loss) income per share — diluted (in dollars per share)	$ 0.05	$ 0.22	$ 0.01	$ 0.63
Anti-dilutive weighted-average shares related to stock award plans (in shares)	326	478	1,255	0