Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost (income)	$ (410)	$ (333)
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1,651	1,731
Expected return on plan assets	(2,116)	(2,133)
Amortization of net actuarial (gain) loss	(3)	(6)
Net periodic benefit cost (income)	(468)	(408)
United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	161	164
Expected return on plan assets	(183)	(170)
Amortization of net actuarial (gain) loss	80	81
Net periodic benefit cost (income)	$ 58	$ 75