Property, Plant and Equipment (Summary of PP&E) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total	$ 664,106	$ 2,576,870
Accumulated depreciation and depletion	(51,509)	(2,034,780)
Property, plant and equipment, net	612,597	542,090
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total	459,973	2,228,539
Buildings, Improvements And Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total	106,790	227,828
Automobiles, Trucks, Tractors and Trailers [Member]
Property, Plant and Equipment [Line Items]
Total	8,523	12,395
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total	20,644	34,246
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Total	5,375	4,793
Land [Member]
Property, Plant and Equipment [Line Items]
Total	43,734	53,952
Oil and Gas Properties [Member]
Property, Plant and Equipment [Line Items]
Total	$ 19,067	$ 15,117