Earnings Per Share - Reconciliation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net income	$ 80,052	$ 61,051	$ 51,537
Shares of common stock and common stock equivalents:
Weighted average shares used in basic computation	137,242	131,770	126,651
Dilutive effect of common stock equivalents	1,583	6,781	13,146
Weighted average shares used in dilutive computation	138,825	138,551	139,797
Basic earnings per share	$ 0.58	$ 0.46	$ 0.41
Diluted earnings per share	$ 0.58	$ 0.44	$ 0.37