Summary of Significant Accounting Policies - Computation of Basic EPS to Dilutive EPS (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net earnings per share, basic, Net Earnings	$ 56,379	$ 53,470	$ 113,297	$ 90,701
Effect of stock options and stock grants, Net Earnings
Net earnings per share, diluted, Net Earnings	$ 56,379	$ 53,470	$ 113,297	$ 90,701
Net earnings per share, basic, Weighted Average Shares	142,245,555	141,973,522	142,196,190	142,045,779
Effect of stock options and stock grants, Weighted Average Shares	919,056	480,561	906,418	473,529
Net earnings per share, diluted, Weighted Average Shares	143,164,611	142,454,083	143,102,608	142,519,308
Net earnings per share, basic, Per Share Amount	$ 0.40	$ 0.38	$ 0.80	$ 0.64
Effect of stock options and stock grants, Per Share Amount	(0.01)		(0.01)
Net earnings per share, diluted, Per Share Amount	$ 0.39	$ 0.38	$ 0.79	$ 0.64