Property, Plant and Equipment, Net (Summary Of Property, Plant And Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Feb. 02, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 541,916		$ 1,995,542
Accumulated depreciation and depletion	(185,642)		(1,587,435)
Property, plant and equipment, net	356,274	$ 540,850	408,107
Machinery And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	360,353		1,727,454
Buildings, Improvements And Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	75,374		171,635
Automobiles, trucks, tractors and trailers [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	6,450		11,742
Furniture And Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	19,668		31,407
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	6,700		4,793
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	28,671		33,394
Oil and Gas Producing Assets [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 44,700		$ 15,117