Pensions and Postretirement Benefits (Summary of Assumptions Used in the Valuation of Pension and Postretirement Benefit Obligations) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Assumptions used to determine benefit obligation at year-end
Rate of compensation increase	3.00%	3.00%	3.00%
Assumptions used to determine expense
Rate of compensation increase	3.00%	3.00%	3.00%
Rate of compensation increase	3.00%	3.00%	3.00%
Pension Benefits
Assumptions used to determine benefit obligation at year-end
Discount rate	3.22%	4.24%	3.52%
Assumptions used to determine expense
Discount rate for benefit obligations	4.11%	3.51%	3.90%
Discount rate for service costs	4.14%	3.60%	3.98%
Discount rate for interest costs	3.72%	3.08%	3.20%
Expected return on plan assets	8.25%	8.25%	8.25%
Postretirement Benefits
Assumptions used to determine benefit obligation at year-end
Discount rate	2.94%	4.06%	3.32%
Health care cost trend rate	6.25%	6.50%	6.50%
Ultimate health care cost trend rate	5.00%	5.00%	5.00%
Assumptions used to determine expense
Discount rate for benefit obligations	4.06%	3.35%	3.61%
Discount rate for service costs	4.34%	3.70%	4.24%
Discount rate for interest costs	3.72%	2.92%	2.90%
Medical health care benefits rate increase	6.50%	6.50%	6.50%
Medical drug benefits rate increase	6.50%	6.50%	6.50%
Ultimate health care cost trend rate	5.00%	5.00%	5.00%