Earnings Per Share - Summary of Reconciliation Between Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Numerator:
Net income	$ 13,658	$ 13,944	$ 26,974	$ 27,443
Less dividends and undistributed earnings allocated to participating securities	(43)	(67)	(122)	(126)
Net income applicable to common shareholders	$ 13,615	$ 13,877	$ 26,852	$ 27,317
Denominator:
Weighted average number of shares outstanding, basic	6,981,907	6,930,268	6,959,856	6,918,779
Earnings per common share - basic	$ 1.95	$ 2.00	$ 3.86	$ 3.95
Numerator:
Net income	$ 13,658	$ 13,944	$ 26,974	$ 27,443
Less dividends and undistributed earnings allocated to participating securities	(43)	(67)	(122)	(126)
Net income applicable to common shareholders	$ 13,615	$ 13,877	$ 26,852	$ 27,317
Denominator:
Weighted average number of shares outstanding, basic	6,981,907	6,930,268	6,959,856	6,918,779
Dilutive effect of common stock equivalents	45,000	69,000	54,000	74,000
Weighted average diluted common shares outstanding	7,026,807	6,998,936	7,013,538	6,993,437
Earnings per common share - diluted	$ 1.94	$ 1.98	$ 3.83	$ 3.91