Pension Plans and Other Postretirement Benefits - Assumed Weighted-Average Rates Used to Determine Benefit Obligations (Detail)	Dec. 31, 2021	Dec. 31, 2020
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	2.75%	2.50%
Pension Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	2.75%	2.50%
Rate of increase in future compensation levels	3.35%	3.37%
Other Postretirement Benefits [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	2.75%	2.50%