Pension And Other Postretirement Benefits (Schedule Of Allocation Of Plan Assets) (Details)	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Actual Allocation	100.00%	100.00%
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%	100.00%
Equity Securities - U.S.
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Actual Allocation	7.00%	6.00%
Equity Securities - International
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Actual Allocation	10.00%	9.00%
Fixed Income Investments
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Actual Allocation	66.00%	68.00%
Hedge Funds
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Actual Allocation	5.00%	5.00%
Private Markets
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Actual Allocation	4.00%	4.00%
Other
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Actual Allocation	7.00%	8.00%
Short-term Investments
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Actual Allocation	1.00%	0.00%
Minimum | Equity Securities - U.S.
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	3.00%	3.00%
Minimum | Equity Securities - International
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	2.00%	2.00%
Minimum | Fixed Income Investments
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	40.00%	40.00%
Minimum | Hedge Funds
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	2.00%	2.00%
Minimum | Private Markets
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%	0.00%
Minimum | Other
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%	0.00%
Minimum | Short-term Investments
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	1.00%	1.00%
Maximum | Equity Securities - U.S.
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10.00%	10.00%
Maximum | Equity Securities - International
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10.00%	10.00%
Maximum | Fixed Income Investments
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	80.00%	80.00%
Maximum | Hedge Funds
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	8.00%	8.00%
Maximum | Private Markets
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	15.00%	15.00%
Maximum | Other
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	14.00%	14.00%
Maximum | Short-term Investments
Defined Benefit Plan, Assets, Target Allocations [Abstract]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	10.00%	10.00%