Property, Plant and Equipment Net Changes in Capitalized Exploratory Well Costs - (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Beginning balance at January 1	$ 207,855	$ 155,103
Additions pending the determination of proved reserves	86,025	41,560
Reclassifications to proved properties based on the determination of proved reserves	0	(2,214)
Capitalized exploratory well costs charged to expense	(13,145)	(4,521)
Balance at September 30	$ 280,735	$ 189,928

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

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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://fasb.org/us-gaap/role/ref/legacyRef
-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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- 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://fasb.org/us-gaap/role/ref/legacyRef
-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

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- References

No definition available.

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- 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://fasb.org/us-gaap/role/ref/legacyRef
-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

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