Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost (income)	$ (330)	$ (392)	$ (663)	$ (784)
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1,731	1,235	3,462	2,469
Expected return on plan assets	(2,133)	(2,201)	(4,266)	(4,401)
Amortization of net actuarial loss	(6)	577	(12)	1,154
Net periodic benefit cost (income)	(408)	(389)	(816)	(778)
United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	169	95	333	196
Expected return on plan assets	(175)	(100)	(345)	(207)
Amortization of net actuarial loss	84	2	165	5
Net periodic benefit cost (income)	$ 78	$ (3)	$ 153	$ (6)