Summary of Significant Accounting Policies - Computation of Basic EPS to Dilutive EPS (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Net earnings per share, basic, Net Earnings	$ 58,928	$ 52,857	$ 172,225	$ 143,558
Net earnings per share, diluted, Net Earnings	$ 58,928	$ 52,857	$ 172,225	$ 143,558
Net earnings per share, basic, Weighted Average Shares	142,334,449	141,980,707	142,242,783	142,023,930
Effect of stock options and stock grants, Weighted Average Shares	884,471	548,535	941,009	495,518
Net earnings per share, diluted, Weighted Average Shares	143,218,920	142,529,242	143,183,792	142,519,448
Net earnings per share, basic, Per Share Amount	$ 0.41	$ 0.37	$ 1.21	$ 1.01
Effect of stock options and stock grants, Per Share Amount			(0.01)
Net earnings per share, diluted, Per Share Amount	$ 0.41	$ 0.37	$ 1.20	$ 1.01