Postretirement Benefit Plans - Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
United States [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net actuarial (gain) loss	$ (9,793)	$ 336	$ (5,174)
Amortization of net actuarial loss	(4,444)	(4,262)	(2,490)
Total recognized in other comprehensive income	(14,237)	(3,926)	(7,664)
Total recognized in net periodic benefit cost and other comprehensive income	(15,470)	(3,743)	(8,008)
United Kingdom [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Net actuarial (gain) loss	(757)	272	(1,144)
Amortization of net actuarial loss	(129)	(79)	(244)
Total recognized in other comprehensive income	(886)	193	(1,388)
Total recognized in net periodic benefit cost and other comprehensive income	$ (720)	$ 169	$ (1,377)