Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 28	$ 690	$ 302
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	6,949	4,923	4,671
Expected return on plan assets	(8,533)	(8,802)	(10,348)
Amortization of net actuarial (gain) loss	(23)	2,277	4,444
Net periodic benefit cost	(1,607)	(1,602)	(1,233)
United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	669	374	357
Expected return on plan assets	(695)	(399)	(320)
Amortization of net actuarial (gain) loss	334	9	129
Net periodic benefit cost	$ 308	$ (16)	$ 166