Employee Retirement Plans and Postretirement Benefits Weighted Average Assumptions (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement discount rate	2.55%	3.44%	3.01%
Rate of compensation increase (as a percent)	2.00%	2.00%	2.00%
Expected return on plan assets (as a percent)	3.24%	4.38%	4.10%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	1.84%	2.55%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase	2.00%	2.00%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement discount rate	2.91%	3.92%	3.34%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	2.10%	2.91%
Other Postretirement Benefits Plan [Member] | Maximum
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate	6.25%	6.50%	6.75%
Other Postretirement Benefits Plan [Member] | Maximum | Determining PBO
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate	6.00%	6.25%
Other Postretirement Benefits Plan [Member] | Minimum
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate	3.57%	4.50%	4.50%
Other Postretirement Benefits Plan [Member] | Minimum | Determining PBO
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate	3.57%	3.57%