Employee Benefit Plans (Schedule of Assumptions Used to Determine Benefit Obligations and Net Periodic Benefit Cost) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Executive Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligation	2.50%	3.20%	4.20%
Discount rate for net periodic benefit cost	3.20%	4.20%	3.60%
Rate of compensation increase for benefit obligation	3.00%	3.00%	3.00%
Rate of compensation increase for net periodic benefit cost	3.00%	3.00%	3.00%
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligation	2.40%	3.20%	4.20%
Discount rate for net periodic benefit cost	3.20%	4.20%	3.60%
Other Postretirement Benefits Plan [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for future years	4.50%	4.50%	5.00%
Other Postretirement Benefits Plan [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Health care cost trend rate assumed for future years	6.50%	7.00%	6.00%