Pension Benefits, Other Postretirement Benefits and Employee Savings and Investment Plans (Assumptions Used) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Pension Benefits
Weighted average assumptions used in benefit obligations:
Discount rate	2.50%	3.25%
Weighted average assumptions used in net periodic benefit costs:
Discount rate	3.25%	4.25%
Expected long-term rate of return on assets	4.53%	4.69%
Other Postretirement Benefits
Weighted average assumptions used in benefit obligations:
Discount rate	1.75%	2.75%
Weighted average assumptions used in net periodic benefit costs:
Discount rate	2.75%	3.75%
Expected long-term rate of return on assets	0.00%	0.00%