Earnings Per Common Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net earnings	$ 10,973	$ 13,198	$ 23,673	$ 24,125
Less earnings attributable to RSUs outstanding	(318)	(246)	(635)	(491)
Net earnings attributable to common stockholders used in basic and diluted earnings per share calculation	$ 10,655	$ 12,952	$ 23,038	$ 23,634
Basic	41,456	41,024	41,420	40,949
Incremental shares from stock-based compensation	11	25	25	19
Diluted	41,467	41,049	41,445	40,968
Basic earnings per common share	$ 0.26	$ 0.32	$ 0.56	$ 0.58
Diluted earnings per common share	$ 0.26	$ 0.32	$ 0.56	$ 0.58