Employee Benefits - Weighted Average Assumptions Used In Determining Net Periodic Cost (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension
Defined Benefit Plan Disclosure [Line Items]
Discount rate in effect for determining service cost	3.20%	3.30%	4.60%
Discount rate in effect for determining interest cost	1.90%	2.40%	3.80%
Expected return on plan assets	6.50%	6.50%	6.80%
Rate of compensation increases	3.00%	3.00%	3.00%
Health Care and Life
Defined Benefit Plan Disclosure [Line Items]
Discount rate in effect for determining service cost	3.00%	3.50%	4.60%
Discount rate in effect for determining interest cost	1.80%	2.80%	4.00%
Expected return on plan assets	4.20%	4.50%	4.30%