Securities - Summary of Amortized Cost and Estimated Fair Values of Debt Securities Held for Investment (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 1,192	$ 2,383
Estimated Fair Value	1,192	2,383
Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	7	13
Estimated Fair Value	7	13
States and Political Subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	685	1,870
Estimated Fair Value	685	1,870
Other Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	500	500
Estimated Fair Value	$ 500	$ 500