Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ (333)	$ (392)
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1,731	1,235
Expected return on plan assets	(2,133)	(2,201)
Amortization of net actuarial (gain) loss	(6)	577
Net periodic benefit cost	(408)	(389)
United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	164	101
Expected return on plan assets	(170)	(107)
Amortization of net actuarial (gain) loss	81	3
Net periodic benefit cost	$ 75	$ (3)