Annual report pursuant to Section 13 and 15(d)

Postretirement Benefits Postretirement Benefits - Additional Information (Details)

v3.20.4
Postretirement Benefits Postretirement Benefits - Additional Information (Details)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]      
Health Care Cost Trend Rate for Next Year 5.30% 5.40%  
Rate to Which the Cost Trend Rate is Assumed to Decline (the Ultimate Trend Rate) 4.50% 4.50%  
Year Rate Reaches the Ultimate Trend Rate 2037 2037  
Pension Plans [Member]      
Defined Benefit Plan, Weighted Average Assumptions Used to Determine Pension and Other Postretirement Benefit Obligations [Abstract]      
Discount Rate 2.00% 2.96%  
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]      
Discount Rate [1],[2] 2.55% 4.13% 3.27%
Long-Term Rate of Return on Plan Assets [3]     4.25%
Other Postretirement Benefit Plans [Member]      
Defined Benefit Plan, Weighted Average Assumptions Used to Determine Pension and Other Postretirement Benefit Obligations [Abstract]      
Discount Rate 2.13% 3.07%  
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Net Periodic Benefit Cost [Abstract]      
Discount Rate [1],[2]   3.85% 3.08%
[1] (B) The Company uses a "spot rate approach" in the calculation of pension and postretirement interest costs to provide a more accurate measurement of interest costs. The spot rate approach applies separate discount rates for each projected benefit payment in the calculation of pension and postretirement interest costs.
[2] The Company utilizes a yield curve analysis to calculate the discount rates used to determine pension and other postretirement benefit obligations. The yield curve analysis matches the cash flows of the Company's benefit obligations. The yield curve consisted of spot interest rates at half year increments for each of the next 30 years and was developed based on pricing and yield information for high quality corporate bonds rated Aa by either Moody's or Standard & Poor's, private placement bonds that are traded in reliance with Rule 144A and are at least two years from date of issuance, bonds with make-whole provisions and bonds issued by foreign corporations that are denominated in U.S. dollars, excluding callable bonds and bonds less than a minimum size and other filtering criteria. Additionally, the Company's yield curve methodology includes bonds having a yield that is greater than the regression mean yield curve as the Company believes this methodology represents an appropriate estimate of the rates at which the Company could effectively settle its pension obligations. For the Company's Salaried and Bargaining plans which were terminated during 2018, the discount rate was a blend of the December 31, 2018 yield curve rate associated with those participants electing annuity contracts to cover future benefit payments, and a lump-sum segment rate for those participants electing lump-sum benefit payments.
[3] The Company evaluates its assumption regarding the estimated long-term rate of return on plan assets based on historical experience, future expectations of investment returns, asset allocations, investment strategies and views of investment professionals.