Investments - Amortized Cost and Fair Value of Securities Held-to-Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Schedule of Held-to-Maturity Securities [Line Items]
Held-to-Maturity, Amortized Cost	$ 1,944	$ 1,948
Held-to-Maturity, Gross Unrecognized Gains	51	25
Held-to-maturity securities	1,995	1,973
Government-Sponsored Residential Mortgage-Backed Securities [Member]
Schedule of Held-to-Maturity Securities [Line Items]
Held-to-Maturity, Amortized Cost	1,104	1,108
Held-to-Maturity, Gross Unrecognized Gains	14
Held-to-maturity securities	1,118	1,108
State and Political Subdivisions [Member]
Schedule of Held-to-Maturity Securities [Line Items]
Held-to-Maturity, Amortized Cost	840	840
Held-to-Maturity, Gross Unrecognized Gains	37	25
Held-to-maturity securities	$ 877	$ 865