Income Taxes (Schedule Of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Allowance for doubtful accounts	$ 1,046	$ 1,713
Operating loss and tax credit carryforwards	84,684	150,426
Compensation and employee benefits	8,832	27,625
Decommissioning liabilities	39,328	30,960
Operating leases	197	2,792
Other assets	30,749	34,578
Deferred tax assets, gross	164,836	248,094
Valuation allowance	(90,781)	(139,106)
Net deferred tax assets	74,055	108,988
Deferred tax liabilities:
Property, plant and equipment	64,721	69,510
Notes receivable	17,812	12,977
Goodwill and other intangible assets	772	23,920
Other liabilities	1,287	7,869
Deferred tax liabilities	83,048	114,276
Net deferred tax liability	$ 8,993	$ 5,288