Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost (income)	$ (392)	$ (236)	$ (784)	$ (477)
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1,235	1,177	2,469	2,354
Expected return on plan assets	(2,201)	(2,586)	(4,401)	(5,171)
Amortization of net actuarial loss	577	1,144	1,154	2,288
Net periodic benefit cost (income)	(389)	(265)	(778)	(529)
United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	95	91	196	179
Expected return on plan assets	(100)	(81)	(207)	(162)
Amortization of net actuarial loss	2	18	5	35
Net periodic benefit cost (income)	$ (3)	$ 28	$ (6)	$ 52