XML 132 R117.htm IDEA: XBRL DOCUMENT v3.22.0.1
Employee Benefits - Weighted Average Assumptions used in Determining Net Periodic Benefit Cost of Health and Welfare Plan (Detail) - Post-Retirement Benefits
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]      
Discount rate 2.00% 2.90% 3.90%
Current medical trend rate 6.50% 6.50% 6.50%
Ultimate trend rate 5.00% 5.00% 5.00%
Year when ultimate trend rate will be reached 2027 2026 2025