Securities - Schedule of Allowance for Credit Losses on Held-to-maturity Securities (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Debt Securities Heldtomaturity Allowance For Credit Loss [Line Items]
Beginning balance	$ 268
Ending balance	265
ASU 2016-13 [Member]
Debt Securities Heldtomaturity Allowance For Credit Loss [Line Items]
Beginning balance	268	$ 326
Current period provision	(3)	(99)
Ending balance	265	227
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	8	(13)
Ending balance	182	117
ASU 2016-13 [Member] | Corporate Debt Securities [Member]
Debt Securities Heldtomaturity Allowance For Credit Loss [Line Items]
Beginning balance	94	196
Current period provision	(11)	(86)
Ending balance	$ 83	$ 110