Investment Securities - Summary of Amortized Cost and Estimated Market Value of Investment Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Available-for-sale Securities, Debt Maturities [Abstract]
Amortized Cost, due in one year or less	$ 2,429
Amortized Cost, due after one year through five years	7,373
Amortized Cost, due after five years through ten years	8,938
Amortized Cost, due after ten years	42,482
Amortized Cost	61,222	$ 54,301
Market Value, due in one year or less	2,341
Market Value, due after one year through five years	6,970
Market Value, due after five years through ten years	7,558
Market Value, due after ten years	36,306
Market Value, total	$ 53,175	$ 48,492