Securities - Summary of Amortized Cost and Estimated Fair Values of Debt Securities Held for Investment (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 2,977	$ 2,964
Gross Unrealized Gains	1	21
Gross Unrealized Losses		(1)
Estimated Fair Value	2,978	2,984
Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	32	59
Gross Unrealized Gains	1	3
Estimated Fair Value	33	62
States and Political Subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	2,445	2,405
Gross Unrealized Gains		18
Gross Unrealized Losses		(1)
Estimated Fair Value	2,445	2,422
Other Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	500	500
Estimated Fair Value	$ 500	$ 500