Investment Securities - Summary of Debt Securities in Unrealized Loss position for Which Allowance for Credit Losses Not Recorded (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 9,362	$ 11,534
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	(76)	(388)
Available-for-sale Securities, 12 Months or Longer, Fair Value	65,103	59,586
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	(4,629)	(5,774)
Available-for-sale Securities, Fair Value, Total	74,465	71,120
Available-for-sale Securities, Unrealized Losses, Total	(4,705)	(6,162)
US Government Agency securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Less than 12 Months, Fair Value		1,995
Available-for-sale Securities, Less than 12 Months, Unrealized Losses		(5)
Available-for-sale Securities, 12 Months or Longer, Fair Value		0
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses		0
Available-for-sale Securities, Fair Value, Total		1,995
Available-for-sale Securities, Unrealized Losses, Total		(5)
Obligations of state and political subdivisions [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Less than 12 Months, Fair Value	5,216	4,836
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	(76)	(247)
Available-for-sale Securities, 12 Months or Longer, Fair Value	32,544	27,736
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	(2,587)	(2,768)
Available-for-sale Securities, Fair Value, Total	37,760	32,572
Available-for-sale Securities, Unrealized Losses, Total	(2,663)	(3,015)
Mortgage-backed securities in government-sponsored entities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Less than 12 Months, Fair Value	4,146	4,703
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	0	(136)
Available-for-sale Securities, 12 Months or Longer, Fair Value	32,078	31,249
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	(2,033)	(2,993)
Available-for-sale Securities, Fair Value, Total	36,224	35,952
Available-for-sale Securities, Unrealized Losses, Total	(2,033)	(3,129)
Other securities [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Securities, Less than 12 Months, Fair Value	0	0
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	0	0
Available-for-sale Securities, 12 Months or Longer, Fair Value	481	601
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	(9)	(13)
Available-for-sale Securities, Fair Value, Total	481	601
Available-for-sale Securities, Unrealized Losses, Total	$ (9)	$ (13)

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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