Retirement, Other Postretirement Benefits, And Defined Contribution Plans (Actuarial Assumptions Used In Determining Net Periodic And Other Postretirement Benefit Obligation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Non-Qualified Pension Plans [Member]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 143.4	$ 131.9
Qualified Pension Plans [Member]
Defined Benefit Plan, Accumulated Benefit Obligation	$ 7,800.0	$ 6,900.0
Net Periodic Pension And Other Postretirement Benefit Costs [Member]
Weighted-average rate of increase in future compensation levels	3.98%	3.98%	3.98%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	4.75%	4.75%	4.75%
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Pre-65 Retirees [Member]
Assumed health care cost trend rate	6.59%	6.95%	6.55%
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2027	2027	2026
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Post - 65 Retirees [Member]
Assumed health care cost trend rate	7.15%	7.25%	7.25%
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2026	2027	2026
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Non-Qualified Pension Plans [Member] | Service Cost [Member]
Weighted-average discount rate	3.94%	3.35%	3.65%
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Non-Qualified Pension Plans [Member] | Interest Cost [Member]
Weighted-average discount rate	3.46%	2.76%	3.10%
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Qualified Pension Plans [Member] | Service Cost [Member]
Weighted-average discount rate	4.57%	3.89%	4.75%
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Qualified Pension Plans [Member] | Interest Cost [Member]
Weighted-average discount rate	4.15%	3.44%	3.73%
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Other Postretirement Benefits Plan [Member] | Service Cost [Member]
Weighted-average discount rate	4.62%	3.88%	4.60%
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Other Postretirement Benefits Plan [Member] | Interest Cost [Member]
Weighted-average discount rate	4.01%	3.33%	3.61%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member]
Weighted-average rate of increase in future compensation levels		3.98%
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	4.75%	4.75%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Pre-65 Retirees [Member]
Assumed health care cost trend rate	6.13%	6.59%
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2027	2027
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Post - 65 Retirees [Member]
Assumed health care cost trend rate	6.25%	7.15%
Defined Benefit Plan, Year Health Care Cost Trend Rate Reaches Ultimate Trend Rate	2027	2026
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Non-Qualified Pension Plans [Member]
Weighted-average discount rate	2.72%	3.98%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Qualified Pension Plans [Member]
Blended weighted-average discount rate	3.39%	4.47%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Other Postretirement Benefits Plan [Member]
Weighted-average discount rate	3.26%	4.42%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Minimum [Member]
Weighted-average rate of increase in future compensation levels	3.98%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Minimum [Member] | Qualified Pension Plans [Member]
Weighted-average discount rate	3.26%	4.37%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Maximum [Member]
Weighted-average rate of increase in future compensation levels	4.40%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Maximum [Member] | Qualified Pension Plans [Member]
Weighted-average discount rate	3.43%	4.52%
Pension Assets [Member] | Net Periodic Pension And Other Postretirement Benefit Costs [Member]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	7.25%	7.50%	7.50%
Other Postretirement Non Taxable Assets [Member] | Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Minimum [Member]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	6.50%	6.50%	6.50%
Other Postretirement Non Taxable Assets [Member] | Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Maximum [Member]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	7.25%	7.50%	7.50%
Taxable [Member] | Net Periodic Pension And Other Postretirement Benefit Costs [Member]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	5.50%	5.50%	5.75%