Other Retirement Benefits - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Defined Contribution Plan Disclosure [Line Items]
Contributions to the plan and charged to benefit costs	$ 66,000	$ 65,000
Defined Contribution 401(k) Plan for Non-Union Employees [Member]
Defined Contribution Plan Disclosure [Line Items]
Minimum period of service of employees to be eligible to participate in plan	1 year
Minimum age of employees to be eligible to participate in plan	21 years
Profit Sharing Contribution Component 401(k) Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Contributions to the plan and charged to benefit costs	$ 91,000	$ 80,000