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, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 69,781	$ 62,964	$ 56,276	$ 51,348	$ 44,001	$ 47,983	$ 189,021	$ 143,332
Basic Net Income Per Share, Weighted average common shares outstanding	170,746			151,930			172,807	151,844
Basic Net Income Per Share	$ 0.41			$ 0.34			$ 1.10	$ 0.95
Effect of dilutive securities: Restricted stock	761			790			672	701
Effect of dilutive securities: Stock options	44			64			48	71
Diluted Net Income Per Share, Weighted average shares outstanding	171,551			152,784			173,527	152,616
Diluted Net Income Per Share	$ 0.41			$ 0.34			$ 1.09	$ 0.94