Summary of Significant Accounting Policies - Computation of Weighted Average Number of Common Shares Outstanding for Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted average common shares	2,980,602	2,980,602
Average treasury shares	(300,700)	(266,557)
Total weighted average common shares outstanding basic	2,679,902	2,714,045
Total weighted average common shares outstanding diluted	2,679,902	2,714,045
Net income	$ 14,756	$ 13,313
Earnings per share basic	$ 5.51	$ 4.91
Earnings per share diluted	$ 5.51	$ 4.91