Retirement, Other Postretirement Benefits, And Defined Contribution Plans (Actuarial Assumptions Used In Determining Pension And Other Postretirement Benefit Obligation) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Postretirement Benefit Obligations And Other Postretirement Accumulated Postretirement Benefit Obligations [Member]
Defined Benefit Plan Disclosure [Line Items]
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]
Defined Benefit Plan Disclosure [Line Items]
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]
Defined Benefit Plan Disclosure [Line Items]
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]
Defined Benefit Plan Disclosure [Line Items]
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]
Defined Benefit Plan Disclosure [Line Items]
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]
Defined Benefit Plan Disclosure [Line Items]
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]
Defined Benefit Plan Disclosure [Line Items]
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]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average discount rate	3.82%	4.49%
Net Periodic Pension And Other Postretirement Benefit Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
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]
Defined Benefit Plan Disclosure [Line Items]
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]
Defined Benefit Plan Disclosure [Line Items]
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
Other Postretirement Non Taxable Assets [Member] | Net Periodic Pension And Other Postretirement Benefit Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
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 Disclosure [Line Items]
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 Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets	7.50%