Net Income Per Share - Summary of Table Reconciling Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net income	$ 37,669	$ 29,134	$ 84,731	$ 74,417
Basic Earnings Per Share, Weighted average common shares outstanding	114,590	111,428	116,272	105,086
Basic Earnings Per Share	$ 0.33	$ 0.26	$ 0.73	$ 0.71
Effect of dilutive securities: Restricted stock	477	446	435	428
Effect of dilutive securities: Stock options	86	73	93	45
Diluted Earnings Per Share, Weighted average shares outstanding	115,153	111,947	116,800	105,559
Diluted earnings per share	$ 0.33	$ 0.26	$ 0.73	$ 0.70