Securities - Schedule of Allowance for Credit Losses on Held-to-maturity Securities (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Debt Securities Heldtomaturity Allowance For Credit Loss [Line Items]
Beginning balance	$ 268
Ending balance	225
ASU 2016-13 [Member]
Debt Securities Heldtomaturity Allowance For Credit Loss [Line Items]
Beginning balance	268	$ 326
Current period provision	(43)	(69)
Ending balance	225	257
ASU 2016-13 [Member] | Obligations of State and Political Subdivisions [Member]
Debt Securities Heldtomaturity Allowance For Credit Loss [Line Items]
Beginning balance	174	130
Current period provision	(2)	35
Ending balance	172	165
ASU 2016-13 [Member] | Corporate Debt Securities [Member]
Debt Securities Heldtomaturity Allowance For Credit Loss [Line Items]
Beginning balance	94	196
Current period provision	(41)	(104)
Ending balance	$ 53	$ 92