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Employee Benefit Plans and Other Postretirement Benefits - Schedule of Assumed Health Care Cost Trend Rates for Postretirement Benefits (Details) - Postretirement Plans
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]      
Health care cost trend rate assumed for next year 6.82% 7.09% 7.24%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) 4.50% 4.50% 4.44%
Year that the rate reaches the ultimate trend rate 2029 2029 2028