Retirement Plans - Actuarial Assumptions Used for Pension Plans & Postretirement Medical Plan (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension Plans
Benefit Obligations:
Discount rate	2.50%	2.20%	2.90%
Rate of compensation increase	3.80%	3.80%	3.80%
Net Periodic Benefit Cost:
Expected return on plan assets	6.60%	6.70%	7.10%
Rate of compensation increase	3.80%	3.80%	3.80%
Pension Plans | Service Cost
Net Periodic Benefit Cost:
Discount rate, Service cost	2.60%	3.20%	3.90%
Pension Plans | Interest Cost
Net Periodic Benefit Cost:
Discount rate, Service cost	1.70%	2.60%	3.40%
Postretirement Medical Plan
Benefit Obligations:
Discount rate	2.40%	1.90%	2.80%
Initial health care trend rate	5.50%	6.00%	6.50%
Ultimate trend rate	4.00%	4.50%	4.50%
Year in which ultimate trend rate is reached	2046	2038	2038