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Retirement Plans (Weighted-Average Actuarial Assumptions Used To Determine Benefit Expense) (Details)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Pension [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Discount rate for benefit obligations 4.23% 3.62% 4.09%
Discount rate for interest on benefit obligations 3.94% 3.27% 3.47%
Discount rate for service cost 4.33% 3.77% 4.41%
Discount rate for interest on service cost 4.30% 3.72% 4.27%
Expected return on plan assets - expense 7.00% 7.00% 7.00%
Compensation increase - expense 4.10% 4.19% 4.13%
OPEB [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Discount rate for benefit obligations 3.79% 3.54% 3.89%
Discount rate for interest on benefit obligations 3.40% 3.14% 3.25%
Discount rate for service cost 3.92% 3.71% 4.25%
Discount rate for interest on service cost 3.85% 3.64% 4.11%
Health care cost trend rate for next year (employees under 65) - expense 5.87% 6.09% 6.31%
Ultimate health care cost trend rate - expense 4.50% 4.50% 4.50%
Year ultimate trend rate reached - expense 2038 2038 2038