Postretirement Benefit Plans - The Weighted Average Assumptions Used to Determine Net Periodic Benefit Costs (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
United States [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	5.50%	2.90%	2.60%
Expected long-term return on plan assets	5.50%	5.50%	6.75%
United Kingdom [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	5.00%	1.80%	1.40%
Expected long-term return on plan assets	4.47%	1.61%	1.13%