Employee Benefit Plans (Summary Of Current Allocation Percentages Of Plan Assets) (Details) - Horizon Defined Benefit Plan	Dec. 31, 2018	Dec. 31, 2017
Common stocks
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets	44.00%	48.00%
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets	21.00%	25.00%
Cash and Cash Equivalents
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets	26.00%	15.00%
Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Percentage of Plan Assets	9.00%	12.00%