Earnings Per Share - Basic and Diluted Weighted Average Shares Outstanding Used to Compute Earnings Per Share (Detail) - $ / shares shares in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share Basic And Diluted [Abstract]
Basic weighted average shares outstanding	37,470	37,303
Dilutive effect of stock options and restricted stock	685	772
Diluted weighted average shares outstanding	38,155	38,075
Basic earnings per share	$ 2.15	$ 2.01
Diluted earnings per share	$ 2.11	$ 1.96