Retirement Benefits (Schedule Of Asset Allocations) (Details)	Dec. 31, 2017
DB Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	100.00%
DB Pension Plans [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	55.00%
DB Pension Plans [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	30.00%
DB Pension Plans [Member] | Alternative Strategy Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	15.00%
OPEB Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	100.00%
OPEB Plan [Member] | Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	52.00%
OPEB Plan [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	25.00%
OPEB Plan [Member] | Alternative Strategy Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	23.00%