Employee Benefits And Deferred Compensation Plans (Schedule Of Target Plan Asset Allocations) (Details) - Pension Benefits [Member]	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Weighted average plan asset allocations	100.00%	100.00%
Equity Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average plan asset allocations	25.93%	67.97%
Fixed Income Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average plan asset allocations	72.17%	30.20%
Cash/Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted average plan asset allocations	1.90%	1.83%