Earnings Per Share - Basic and Diluted Weighted Average Shares Outstanding Used to Compute Earnings Per Share (Detail) - $ / shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share Basic And Diluted [Abstract]
Basic weighted average shares outstanding	37,529	37,386	37,502	37,343
Dilutive effect of stock options and restricted stock	555	774	612	786
Diluted weighted average shares outstanding	38,084	38,160	38,114	38,129
Basic earnings per share	$ 1.54	$ 1.81	$ 5.49	$ 6.06
Diluted earnings per share	$ 1.52	$ 1.78	$ 5.40	$ 5.94