Net Income per Share (Net Income Per Basic and Diluted Share) (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Numerator
Income used to compute net income per diluted share	$ 20,732	$ 13,907	$ 88,412	$ 73,942
Denominator
Total weighted-average shares used to compute net income per basic share (in Shares)	151,146	163,856	156,802	163,771
Diluted (in Shares)	152,317	164,285	157,529	164,075
Basic (in Dollars per Share)	$ 0.14	$ 0.08	$ 0.56	$ 0.45
Net income per diluted share (in Dollars per Share)	$ 0.14	$ 0.08	$ 0.56	$ 0.45
Restricted Stock [Member]
Debt Instrument [Line Items]
Additional shares included in the calculation of diluted EPS (in Shares)	1,171	429	727	304