Property, Plant and Equipment (Schedule Of Property, Plant And Equipment) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment, Net [Abstract]
Building and improvements	$ 17,426	$ 17,426
Plant and equipment	1,825,332	1,804,684
Other	97,402	88,077
Property, plant and equipment, gross	1,940,160	1,910,187
Less: Accumulated depreciation	(882,768)	(795,167)
Property, plant and equipment, net, before construction in progress	1,057,392	1,115,020
Construction in progress	45,603	33,245
Property, plant and equipment, net	1,102,995	1,148,265
Depreciation expense	$ 89,454	$ 88,197	$ 91,154

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount before accumulated depreciation of building structures held for productive use including addition, improvement, or renovation to the structure, including, but not limited to, interior masonry, interior flooring, electrical, and plumbing.

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Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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Amount before accumulated depreciation of tangible personal property used to produce goods and services, including, but is not limited to, tools, dies and molds, computer and office equipment.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount before accumulated depreciation, depletion and amortization of other physical assets used in the normal conduct of business to produce goods and services and not intended for resale.

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Gross amount, at the balance sheet date, of long-lived physical assets used in the normal conduct of business and not intended for resale. This can include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. Does not include construction in progress.

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Tangible assets that are held by an entity for use in the production or supply of goods and services, for rental to others, or for administrative purposes and that are expected to provide economic benefit for more than one year; net of accumulated depreciation. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. Does not include construction in progress.

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