Property, Plant and Equipment, Net (Summary Of Property, Plant And Equipment) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 544,119	$ 519,066
Accumulated depreciation and depletion	(250,025)	(236,690)
Property, plant and equipment, net	294,094	282,376
Machinery And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	397,539	378,907
Buildings, Improvements And Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	69,691	70,816
Automobiles, Trucks, Tractors and Trailers [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	6,689	6,376
Furniture And Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	19,378	19,373
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	12,191	5,185
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	26,049	26,695
Oil and Gas Producing Assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 12,582	$ 11,714