Earnings Per Share - Calculation of Basic Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net income	$ 4,983	$ 4,909	$ 4,804	$ 4,105	$ 9,892	$ 8,909
Less: distributed earnings allocated to participating securities	(14)		(13)		(29)	(26)
Less: undistributed earnings allocated to participating securities	(23)		(22)		(46)	(40)
Net earnings available to common shareholders	$ 4,946		$ 4,769		$ 9,817	$ 8,843
Weighted average common shares outstanding including participating securities	11,191,043		11,129,341		11,194,011	11,132,105
Less: average unvested restricted shares	(84,125)		(80,062)		(85,353)	(82,397)
Weighted average common shares outstanding	11,106,918		11,049,279		11,108,658	11,049,708
Basic and diluted earnings per share	$ 0.44		$ 0.43		$ 0.88	$ 0.80