Property, Plant and Equipment (Summary of PP&E) (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Feb. 02, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total	$ 554,189		$ 1,995,542
Accumulated depreciation and depletion	(150,716)		(1,587,435)
Property, plant and equipment, net	403,473	$ 540,850	408,107
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total	391,750		1,727,454
Buildings, Improvements And Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total	79,071		171,635
Automobiles, Trucks, Tractors and Trailers [Member]
Property, Plant and Equipment [Line Items]
Total	7,729		11,742
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total	19,997		31,407
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Total	4,257		4,793
Land [Member]
Property, Plant and Equipment [Line Items]
Total	31,067		33,394
Oil and Gas Properties [Member]
Property, Plant and Equipment [Line Items]
Total	$ 20,318		$ 15,117