Employee Benefit Plans and Other Postretirement Benefits - Schedule Of Assumptions Used To Determine Net Periodic Benefit Cost (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension and SERPA Benefits
Assumptions for benefit obligations:
Discount rate	2.62%	3.49%	4.38%
Rate of compensation increase	3.34%	3.39%	3.38%
Assumptions for net periodic benefit cost:
Discount rate	3.49%	4.38%	3.71%
Expected return on plan assets	6.70%	7.10%	7.25%
Rate of compensation increase	3.39%	3.38%	3.43%
Postretirement Health Coverage
Assumptions for benefit obligations:
Discount rate	2.11%	3.26%	4.23%
Assumptions for net periodic benefit cost:
Discount rate	3.26%	4.23%	3.52%
Expected return on plan assets	7.00%	7.25%	7.25%