Earnings Per Share - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net income	$ 12,572	$ 7,449	$ 29,049	$ 24,575
Denominator:
Weighted-average shares outstanding for basic earnings per share	11,302	11,672	11,572	11,649
Effect of dilutive securities	375	461	352	452
Weighted-average shares adjusted for dilutive securities	11,677	12,133	11,924	12,101
Basic	$ 1.11	$ 0.64	$ 2.51	$ 2.11
Diluted	$ 1.08	$ 0.61	$ 2.44	$ 2.03