Maturity period of highly liquid investments.

No definition available.

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- Definition

Nature of business and presentation.

+ References

No definition available.

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- Definition

Net operating loss carryforwards written off.

+ References

No definition available.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

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-Section 50
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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- Definition

The expense recorded to reduce the value of oil and gas assets consisting of proved properties and unproved properties as the estimate of future successful production from these properties is reduced.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2921-110230

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
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-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 360
-Section 35
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=66906256&loc=d3e66150-109466

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- Definition

Amount recognized for uncertainty in income taxes classified as current.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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Basis of Presentation - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Nature Of Business And Presentation [Line Items]
Maturity period of highly liquid investments	three months or less
Impairment of oil and gas properties	$ 12,169,000	$ 33,413,000
Net operating loss carryforward, wrote off			$ 141,700,000
Liability for material uncertain tax positions	$ 0	0
Option vesting period	3 years
Corporate Headquarter
Nature Of Business And Presentation [Line Items]
Estimated useful lives	30 years
Unproved Oil and Gas Properties
Nature Of Business And Presentation [Line Items]
Impairment of oil and gas properties	$ 12,200,000	28,600,000
Proven Oil and Gas Properties
Nature Of Business And Presentation [Line Items]
Impairment of oil and gas properties		$ 4,800,000
Minimum \| Other Property and Equipment
Nature Of Business And Presentation [Line Items]
Estimated useful lives	3 years
Maximum \| Other Property and Equipment
Nature Of Business And Presentation [Line Items]
Estimated useful lives	5 years
Sales Revenue, Net \| Customer Concentration Risk \| Enterprise Crude Oil LLC
Nature Of Business And Presentation [Line Items]
Concentration risk, percentage	27.00%
Sales Revenue, Net \| Customer Concentration Risk \| Trafigura AG
Nature Of Business And Presentation [Line Items]
Concentration risk, percentage		14.00%
Sales Revenue, Net \| Customer Concentration Risk \| Shell Trading (US) Company
Nature Of Business And Presentation [Line Items]
Concentration risk, percentage	15.00%	20.00%
Sales Revenue, Net \| Customer Concentration Risk \| Texla Energy Management, Inc
Nature Of Business And Presentation [Line Items]
Concentration risk, percentage	15.00%	16.00%
Sales Revenue, Net \| Customer Concentration Risk \| Vitol Inc
Nature Of Business And Presentation [Line Items]
Concentration risk, percentage	16.00%	35.00%
Sales Revenue, Net \| Customer Concentration Risk \| NGL Crude Logistics LLC
Nature Of Business And Presentation [Line Items]
Concentration risk, percentage	11.00%	10.00%
Accounts Receivable \| Customer Concentration Risk \| Enterprise Crude Oil LLC
Nature Of Business And Presentation [Line Items]
Concentration risk, percentage	37.00%
Accounts Receivable \| Customer Concentration Risk \| Phillips 66
Nature Of Business And Presentation [Line Items]
Concentration risk, percentage	23.00%
Accounts Receivable \| Customer Concentration Risk \| Shell Trading (US) Company
Nature Of Business And Presentation [Line Items]
Concentration risk, percentage	22.00%	19.00%
Accounts Receivable \| Customer Concentration Risk \| Vitol Inc
Nature Of Business And Presentation [Line Items]
Concentration risk, percentage		59.00%
Accounts Receivable \| Customer Concentration Risk \| NGL Crude Logistics LLC
Nature Of Business And Presentation [Line Items]
Concentration risk, percentage	10.00%	17.00%