Earnings Per Share - Calculation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share Basic [Abstract]
Net income	$ 10,800	$ 19,400
Basic weighted average common shares	19,266,016	19,229,134
Basic earnings per common share	$ 0.56	$ 1.01
Net income	$ 10,800	$ 19,400
Weighted average common shares	19,266,016	19,229,134
Stock options and restricted stock	86,229	68,902
Diluted weighted average common shares	19,352,245	19,298,036
Diluted earnings per common share	$ 0.56	$ 1.01