Net Income Per Share - Reconciliation of Numerator and Denominator of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Numerator
Net income	$ 3,335	$ 21,198
Denominator
Weighted average shares outstanding, basic	134,168	134,777
Effect of dilutive potential common shares	3,124	4,456
Weighted average shares outstanding, diluted	137,292	139,233
Basic net income per share	$ 0.02	$ 0.16
Diluted net income per share	$ 0.02	$ 0.15
Antidilutive employee stock-based awards, excluded	793	330