Shareholders' Equity - Summary of Table Reconciling Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 49,185	$ 69,781	$ 62,964	$ 56,276	$ 47,498	$ 51,348	$ 44,001	$ 47,983	$ 238,206	$ 190,830	$ 95,725
Basic Net Income Per Share, Weighted average common shares outstanding	169,235	170,746	172,985	174,734	167,044	151,930	151,878	151,721	171,907	155,675	137,821
Basic Net Income Per Share	$ 0.29	$ 0.41	$ 0.37	$ 0.32	$ 0.28	$ 0.34	$ 0.29	$ 0.32	$ 1.39	$ 1.23	$ 0.69
Effect of dilutive securities: Restricted stock									733	796	599
Effect of dilutive securities: Stock options									47	68	93
Diluted Net Income Per Share, Weighted average shares outstanding	170,186	171,551	173,675	175,368	167,992	152,784	152,568	152,370	172,687	156,539	138,513
Diluted Net Income Per Share	$ 0.29	$ 0.41	$ 0.36	$ 0.32	$ 0.28	$ 0.34	$ 0.29	$ 0.31	$ 1.38	$ 1.22	$ 0.69