Employee Benefits - Weighted Average Assumptions Used to Determine Postretirement Benefit Expense and Obligation (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Liability
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.10%	5.40%
Current medical cost trend rate	7.25%	6.50%
Ultimate medical cost trend rate	4.75%	4.75%
Expense
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.40%	2.90%
Current medical cost trend rate	6.50%	6.75%
Ultimate medical cost trend rate	4.75%	4.75%