Property, Plant and Equipment (PPE By Type) (Details) - USD ($) $ in Thousands	Dec. 27, 2019	Dec. 28, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 680,204	$ 570,033
Accumulated depreciation	(354,658)	(340,738)
Net property, plant and equipment	325,546	229,295
Land and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	29,817	26,252
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	182,195	157,385
Manufacturing equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	320,240	317,011
Office, warehouse and automotive equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	48,476	44,901
Additions in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 99,476	$ 24,484

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, depletion and amortization of physical assets used in the normal conduct of business 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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