Investment Securities - Summary of Fixed Maturity Securities Available for Sale (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 61,222	$ 54,301
Gross Unrealized Gains	12	13
Gross Unrealized Losses	(8,059)	(5,822)
Fair Value	53,175	48,492
Mortgage-backed Securities, Principally Obligations of US Federal Agencies [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	45,300	43,286
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(6,344)	(4,933)
Fair Value	38,956	38,353
State and Municipalities [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	13,733	11,015
Gross Unrealized Gains	12	13
Gross Unrealized Losses	(1,650)	(889)
Fair Value	12,095	$ 10,139
Agency Bonds [Member]
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,189
Gross Unrealized Gains	0
Gross Unrealized Losses	(65)
Fair Value	$ 2,124