Investments - Amortized Cost and Fair Value of Securities Held-to-Maturity (Detail) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Schedule of Held-to-Maturity Securities [Line Items]
Held-to-Maturity, Amortized Cost	$ 5,217	$ 2,209
Held-to-Maturity, Gross Unrecognized Gains	29	41
Held-to-Maturity, Gross Unrecognized Losses	(32)
Held-to-maturity securities	5,214	2,250
Government-Sponsored Residential Mortgage-Backed Securities [Member]
Schedule of Held-to-Maturity Securities [Line Items]
Held-to-Maturity, Amortized Cost	3,932	1,094
Held-to-Maturity, Gross Unrecognized Gains	3	3
Held-to-Maturity, Gross Unrecognized Losses	(26)
Held-to-maturity securities	3,909	1,097
State and Political Subdivisions [Member]
Schedule of Held-to-Maturity Securities [Line Items]
Held-to-Maturity, Amortized Cost	1,285	1,115
Held-to-Maturity, Gross Unrecognized Gains	26	38
Held-to-Maturity, Gross Unrecognized Losses	(6)
Held-to-maturity securities	$ 1,305	$ 1,153