Employee Benefit Plans (Schedule of Assumptions Used to Calculate Benefit Obligations) (Details)	Dec. 31, 2020	Dec. 31, 2019
Other postretirement benefits plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	2.17%	3.09%
Excess Plan | Defined benefit pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	1.96%	2.90%
Cash Balance | Defined benefit pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	2.19%	3.09%