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	3 Months Ended								12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2022	Dec. 31, 2021
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted average common shares									2,980,602	2,980,602
Average treasury shares									(266,557)	(247,476)
Total weighted average common shares outstanding basic									2,714,045	2,733,126
Total weighted average common shares outstanding diluted									2,714,045	2,733,126
Net income	$ 3,753	$ 3,650	$ 3,209	$ 2,701	$ 2,306	$ 2,901	$ 2,745	$ 2,885	$ 13,313	$ 10,837
Basic Earnings Per Share	$ 1.39	$ 1.35	$ 1.18	$ 0.99	$ 0.85	$ 1.06	$ 1.00	$ 1.05	$ 4.91	$ 3.97
Diluted Earnings Per Share	$ 1.39	$ 1.35	$ 1.18	$ 0.99	$ 0.85	$ 1.06	$ 1.00	$ 1.05	$ 4.91	$ 3.97