Property And Equipment, Net (Schedule Of Property And Equipment) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Proved properties	$ 6,685,543	$ 6,278,321
Accumulated depreciation, depletion and amortization and impairments	(4,098,202)	(3,944,851)
Proved properties, net	2,587,341	2,333,470
Unproved properties, not being amortized
Unevaluated leasehold and seismic costs	580,369	608,830
Capitalized interest	76,607	65,003
Total unproved properties, not being amortized	656,976	673,833
Other property and equipment	30,580	29,191
Accumulated depreciation	(19,392)	(17,970)
Other property and equipment, net	11,188	11,221
Total property and equipment, net	$ 3,255,505	$ 3,018,524

Costs Not Subject To Amortization, Capitalized Interest

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Costs Not Subject To Amortization, Unevaluated Leaseholds And Seismic Costs

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The Net Carrying amounts as of the balance sheet date of proved oil and gas properties based on full cost accounting.

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Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount of accumulated depreciation, depletion, amortization and valuation allowance relating to oil and gas producing activities.

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The sum of the capitalized costs incurred, as of the balance sheet date, of unproved properties excluded from amortization including acquisition costs, exploration costs, development costs, and production costs.

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Capitalized costs of proved properties incurred for any combination mineral interests acquisitions; wells and related equipment; support equipment and facilities; and uncompleted wells and equipment and other costs not previously disclosed within this table.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount before accumulated depreciation, depletion and amortization of other physical assets used in the normal conduct of business to produce goods and services and not intended for resale.

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Amount after depreciation of long-lived, physical assets used to produce goods and services and not intended for resale, classified as other.

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