Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ (253)	$ (417)	$ (508)	$ (827)
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1,700	1,652	3,400	3,303
Expected return on plan assets	(2,003)	(2,124)	(4,005)	(4,240)
Amortization of net actuarial (gain) loss	(19)	(3)	(38)	(6)
Net periodic benefit cost	(322)	(475)	(643)	(943)
United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	178	160	346	321
Expected return on plan assets	(206)	(182)	(400)	(365)
Amortization of net actuarial (gain) loss	97	80	189	160
Net periodic benefit cost	$ 69	$ 58	$ 135	$ 116