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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net income	$ 51,348	$ 39,372	$ 143,332	$ 114,218
Basic Net Income Per Share, Weighted average common shares outstanding	151,930	135,120	151,844	135,040
Basic Net Income Per Share	$ 0.34	$ 0.30	$ 0.95	$ 0.85
Effect of dilutive securities: Restricted stock	790	589	701	558
Effect of dilutive securities: Stock options	64	87	71	95
Diluted Net Income Per Share, Weighted average shares outstanding	152,784	135,796	152,616	135,693
Diluted Net Income Per Share	$ 0.34	$ 0.29	$ 0.94	$ 0.84