Exploratory Well Costs (Details) $ in Thousands	6 Months Ended
Jun. 30, 2018 USD ($)
Capitalized Exploratory Well Costs that are Pending Determination of Proved Reserves [Roll Forward]
Balance at January 1	$ 2,167
Additions Pending the Determination of Proved Reserves	3,512
Reclassifications to Proved Properties	(5,250)
Costs Charged to Expense	(429)
Balance at June 30	$ 0

Additions to capitalized exploratory well costs that were added during the reporting period pending the determination of proved reserves.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 1B
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=68064819&loc=SL6806780-109447

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of expense for capitalized exploratory well costs for which proved reserves were not found at the exploratory well.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 1B
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=68064819&loc=SL6806780-109447

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of capitalized exploratory well costs that is pending the determination of proved reserves. This does not include amounts that were capitalized and subsequently expensed in the same annual period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=68064819&loc=SL6806780-109447

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Previously capitalized costs of the drilling of wells that were reclassified as part of the costs of the enterprise's wells and related equipment and facilities at the time that proved reserves were found.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 235
-Section 50
-Paragraph 1B
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=68064819&loc=SL6806780-109447

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration