Earnings Per Share - Computation of Earnings Per Share (Detail) - USD ($) shares in Thousands, $ 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 income	$ 27,422	$ 17,606	$ 89,433	$ 41,157
Average number of common shares outstanding (in shares)	29,714	29,764	29,720	29,971
Effect of dilutive stock options and restricted stock (in shares)	137	80	167	112
Average number of common shares outstanding used to calculate diluted earnings per share (in shares)	29,851	29,844	29,887	30,083
Options excluded from diluted earnings per share because of their antidilutive effect (in shares)	0	0	0	0