Summary Of Significant Accounting Policies (Schedule Of Estimated Useful Lives Of Assets) (Details)	12 Months Ended
	Dec. 31, 2019
Plant, Buildings And Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years
Plant, Buildings And Improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Production Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years
Production Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Other Machinery and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Other Machinery and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
Railroad Track and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	20 years
Computer Hardware And Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Computer Hardware And Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Office Furniture and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	7 years
Office Furniture and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years