Investment Securities - Additional Information (Detail)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025 USD ($) Securities	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) Securities	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) Securities
Debt Securities, Available-for-Sale [Line Items]
Allowance for credit losses on available for sale debt securities	$ 0		$ 0		$ 0
Number of debt securities with unrealized losses | Securities	181		181		210
Proceeds from sales	$ 0	$ 0	$ 0	$ 1,691,000
Accrued interest receivable on available for sale debt securities	1,183,000		$ 1,183,000
Held to maturity debt securities with unrealized losses | Securities			9		10
Accrued interest receivable on held-to-maturity debt securities	165,000		$ 165,000
Tax (provision) benefit		$ 1,000		$ 1,000
Pledged debt securities with a carrying value	$ 55,778,000		$ 55,778,000		$ 57,852,000