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Summary of Significant Accounting Policies Other (Details)

12 Months Ended

Dec. 31, 2018

USD ($)

Dec. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Dec. 31, 2016

Feb. 21, 2019

Concentration of Credit Risk and Major Customers [Abstract]

Entity-Wide Revenue, Major Customer, Percentage

100.00%

^[1]

100.00%

^[2]

100.00%

^[3]

Number of individual entities within groups of entities under common ownership that represent more than 10 percent of total production revenue

0

Revolving Credit Facility [Member] | Line of Credit [Member]

Basis of Presentation and Significant Accounting Policies [Line Items]

Long-term Line of Credit

$ 0

$ 0

$ 0

Minimum [Member]

Revenues [Abstract]

Revenue Receipt, Days After Sale

30

Maximum [Member]

Revenues [Abstract]

Revenue Receipt, Days After Sale

90

Oil and Gas Properties [Member]

Impairment of Proved, Unproved, and Other Properties [Abstract]

Period of New York Mercantile Exchange Strip Pricing Used for Price Forecast

5 years

Property, Plant and Equipment, Other Types [Member] | Minimum [Member]

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment, Estimated Useful Lives

3 years

Property, Plant and Equipment, Other Types [Member] | Maximum [Member]

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment, Estimated Useful Lives

30 years

Customer Concentration Risk [Member] | Oil, gas, and NGLS revenue [Member] | Major Customer One [Member]

Concentration of Credit Risk and Major Customers [Abstract]

Entity-Wide Revenue, Major Customer, Percentage

^[4]

18.00%

6.00%

0.00%

Customer Concentration Risk [Member] | Oil, gas, and NGLS revenue [Member] | Major Customer Two [Member]

Concentration of Credit Risk and Major Customers [Abstract]

Entity-Wide Revenue, Major Customer, Percentage

^[4]

10.00%

10.00%

5.00%

Customer Concentration Risk [Member] | Oil, gas, and NGLS revenue [Member] | Unnamed Major Customer One with Related Entities [Member]

Concentration of Credit Risk and Major Customers [Abstract]

Entity-Wide Revenue, Major Customer, Percentage

^[5]

18.00%

17.00%

15.00%

Customer Concentration Risk [Member] | Oil, gas, and NGLS revenue [Member] | Unnamed Major Customer Two with Related Entities [Member]

Concentration of Credit Risk and Major Customers [Abstract]

Entity-Wide Revenue, Major Customer, Percentage

^[5]

12.00%

8.00%

8.00%

Measurement Input, Discount Rate [Member] | Oil and Gas Properties [Member] | Minimum [Member]

Basis of Presentation and Significant Accounting Policies [Line Items]

Fair Value Assumptions, Measurement Input

0.10

0.10

Measurement Input, Discount Rate [Member] | Oil and Gas Properties [Member] | Maximum [Member]

Basis of Presentation and Significant Accounting Policies [Line Items]

Fair Value Assumptions, Measurement Input

0.15

0.15

Measurement Input, Risk Free Interest Rate [Member] | Asset Retirement Obligation Costs [Member] | Minimum [Member]

Basis of Presentation and Significant Accounting Policies [Line Items]

Fair Value Assumptions, Measurement Input

0.055

0.055

Measurement Input, Risk Free Interest Rate [Member] | Asset Retirement Obligation Costs [Member] | Maximum [Member]

Basis of Presentation and Significant Accounting Policies [Line Items]

Fair Value Assumptions, Measurement Input

0.12

0.12

Subsequent Event [Member]

Concentration of Credit Risk and Major Customers [Abstract]

Number of Derivative Counterparties

10

[1]	Note: Amounts may not calculate due to rounding.
[2]	Note: Amounts may not calculate due to rounding.
[3]	Note: Amounts may not calculate due to rounding.
[4]	(1) These major customers are purchasers of a portion of the Company’s production from its Permian region.
[5]	(2) In the aggregate, these groups of entities under common ownership represented more than 10 percent of total oil, gas, and NGL production revenue for at least one of the periods presented; however, no individual entity comprising either group represented more than 10 percent of the Company’s total oil, gas, and NGL production revenue.

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Assumption used in valuing an instrument.

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Impairment of Proved, Unproved, and Other Properties [Abstract]

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Major Customers [Abstract]

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- Definition

The number of derivative counterparties that are affiliates of the lenders under the Credit Agreement, and that must have investment grade senior unsecured debt ratings.

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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.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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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.

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