Earnings per Share - Schedule of Earnings per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Basic earnings per share, Net Income	$ 98,028	$ 95,988	$ 113,659	$ 55,841
Diluted earnings per share, Net Income	$ 98,028	$ 95,988	$ 113,659	$ 55,841
Basic earnings per share, Shares	78,164	86,616	81,003	86,410
Effect of dilutive incentive-based awards, Shares	640	926	735	619
Diluted earnings per share, Shares	78,804	87,542	81,738	87,029
Basic earnings per share, Per Share Amount	$ 1.25	$ 1.11	$ 1.40	$ 0.65
Diluted earnings per share, Per Share Amount	$ 1.24	$ 1.10	$ 1.39	$ 0.64