Retirement Benefits (Schedule Of Asset Allocations) (Details)	Dec. 31, 2020
DB Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	100.00%
DB Pension Plans | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	55.00%
DB Pension Plans | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	34.00%
DB Pension Plans | Multi-asset investments
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	11.00%
OPEB Plan
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	100.00%
OPEB Plan | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	50.00%
OPEB Plan | Fixed-income securities
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	30.00%
OPEB Plan | Multi-asset investments
Defined Benefit Plan Disclosure [Line Items]
Asset allocation	20.00%