Postretirement Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ (392)	$ (241)
United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1,235	1,177
Expected return on plan assets	(2,201)	(2,586)
Amortization of net actuarial loss	577	1,144
Net periodic benefit cost	(389)	(265)
United Kingdom [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	101	88
Expected return on plan assets	(107)	(81)
Amortization of net actuarial loss	3	17
Net periodic benefit cost	$ (3)	$ 24