Retirement, Other Postretirement Benefits, And Defined Contribution Plans (Actuarial Assumptions Used In Determining Net Periodic And Other Postretirement Benefit Obligation) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Periodic Pension And Other Postretirement Benefit Costs [Member]
Weighted-average rate of increase in future compensation levels	3.98%	4.23%	4.23%
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	6.55%	6.75%	7.10%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate	2026	2024	2023
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Post - 65 Retirees [Member]
Assumed health care cost trend rate	7.25%	7.55%	7.70%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate	2026	2024	2023
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Qualified Pension Plans [Member] | Service Cost [Member]
Weighted-average discount rate	4.75%	5.00%	4.27%
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Qualified Pension Plans [Member] | Interest Cost [Member]
Weighted-average discount rate	3.73%	3.90%	4.27%
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Other Postretirement Benefit Plan [Member] | Service Cost [Member]
Weighted-average discount rate	4.60%	4.92%	4.23%
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Other Postretirement Benefit Plan [Member] | Interest Cost [Member]
Weighted-average discount rate	3.61%	3.78%	4.23%
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Non-Qualified Pension Plans [Member] | Service Cost [Member]
Weighted-average discount rate	3.65%	3.65%	3.61%
Net Periodic Pension And Other Postretirement Benefit Costs [Member] | Non-Qualified Pension Plans [Member] | Interest Cost [Member]
Weighted-average discount rate	3.10%	3.10%	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%	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	6.95%	6.55%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate	2027	2026
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Post - 65 Retirees [Member]
Assumed health care cost trend rate	7.25%	7.25%
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate	2027	2026
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Qualified Pension Plans [Member]
Blended weighted-average discount rate	3.78%	4.39%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Other Postretirement Benefit Plan [Member]
Weighted-average discount rate	3.72%	4.30%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Non-Qualified Pension Plans [Member]
Weighted-average discount rate	3.34%	3.63%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Minimum [Member] | Qualified Pension Plans [Member]
Weighted-average discount rate	3.70%	4.30%
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member] | Maximum [Member] | Qualified Pension Plans [Member]
Weighted-average discount rate	3.82%	4.49%
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 Return on Assets	7.50%	7.75%	8.25%
Other Postretirement Non Taxable Assets [Member] | Net Periodic Pension And Other Postretirement Benefit Costs [Member]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets		7.75%	8.05%
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 Return on Assets	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 Return on Assets	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 Return on Assets	5.75%	6.00%	6.25%