Properties, Plant and Equipment - Oil and Gas Properties - Tabular Information (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Mineral interests in properties
Unproved	$ 75,308	$ 94,526
Proved	1,031,669	1,001,194
Wells and equipment and related facilities	1,289,323	1,094,202
Gross oil and gas properties	2,396,300	2,189,922
Less: Accumulated depletion and impairment	(760,534)	(551,062)
Net oil and gas properties	$ 1,635,766	$ 1,638,860

Capitalized costs which include those incurred to (1) to drill and equip those exploratory wells and exploratory-type stratigraphic test wells that have found proved reserves and (2) obtain access to proved reserves and provide facilities for extracting, treating, gathering, storing the oil and gas, including the drilling and equipping of development wells and development-type stratigraphic wells and service wells.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6528444

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Amount of accumulated depreciation, depletion, amortization and impairment of oil and gas property carried under the successful effort method.

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Oil and Gas properties, gross, carried under the successful effort method.

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Oil and gas properties net of accumulated depreciation, depletion, amortization, impairment, and abandonment, carried under the successful effort method.

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Oil and Gas properties with proved reserves under the successful effort method.

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Oil and Gas properties with unproved reserves under the successful effort method.

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