Supplemental Information On Oil And Gas Exploration And Production Activities (Unaudited) - Costs Incurred Related to Oil and Gas Activities (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Acquisition cost:
Proved	$ 48,116	$ 4,508	$ 74,728
Unproved	26,600	10,646	36,236
Exploration costs:
Geological and geophysical	5	142	111
Development costs	28,577	56,862	75,105
Total additions	$ 103,298	$ 72,158	$ 186,180

Costs incurred exploration costs geological and geophysical.

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- Definition

Costs incurred exploration costs of oil and gas properties.

+ References

No definition available.

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- Definition

Costs incurred, including capitalized costs and costs charged to expense, associated with the acquisition of oil and gas properties that have proved reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 18
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62014-109447

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 19
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62038-109447

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- Definition

Costs incurred, including capitalized costs and costs charged to expense, associated with the acquisition of oil and gas properties that have unproved reserves.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 19
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62038-109447

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 18
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e62014-109447

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- Definition

Development costs incurred, including capitalized costs and costs charged to expense, in oil and gas activities.

+ References

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- Definition

Amount of costs incurred related to oil and gas property acquisition, exploration and development activities, including capitalized costs and costs charged to expense.

+ References

No definition available.

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