Acres exchange in first trade.

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- Definition

Acres exchange in trade.

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No definition available.

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Cost related to sale of oil and gas properties.

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No definition available.

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- Definition

Gain (loss) on sale of unproved leases.

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No definition available.

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Proceeds from sale of unproved leases.

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No definition available.

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Proceeds from sale of unproved property.

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No definition available.

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- Definition

This represents the reduction to PP&E balance during the period relating to acreage trades with third parties.

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No definition available.

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- Definition

Area of land held.

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No definition available.

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- Definition

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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-Subparagraph (c)
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- Definition

Amount classified as assets attributable to disposal group held for sale or disposed of, expected to be disposed of within one year or the normal operating cycle, if longer.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of gain (loss) on sale or disposal of proven and unproven oil and gas properties.

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Amount of gain (loss) on sale or disposal of property without proven oil and gas reserves.

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Amount of gain (loss) on sale or disposal of assets utilized in financial service operations.

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No definition available.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

The cash inflow to dispose of long-lived, physical assets and mineral interests in oil and gas properties used for normal oil and gas operations.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Amount of divestiture of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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No definition available.

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Sale of Oil and Natural Gas Property Interests - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017 USD ($) a	Dec. 31, 2016 USD ($) a	Dec. 31, 2015 USD ($) a
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of conventional oil and gas properties and related equipment		$ 4,700,000
Gain (loss) on sale of assets	$ 179,000	(6,936,000)	$ 4,737,000
Assets held for sale	206,000	468,000
Gain or loss on sale of conventional oil and gas properties and related equipment		1,100,000
Proceeds from sale of unproved lease properties		3,900,000
Gain or Loss on sale of oil and natural gas properties		0
Proceeds from sale of unproved lease properties		4,800,000
Gain (loss) on sale of unproved properties		0
Acreage Trades [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain or loss on sale of conventional oil and gas properties and related equipment		0	$ 0
Proceeds from sale of asset		$ 1,600,000
Area of land \| a		249.5	10,500
Acres exchange in first trade \| a			7,000
Credit related to reimbursement of capital expenditures			$ 17,500,000
Maximum [Member] \| Acreage Trades [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Acres exchange in trade \| a			1,500
Assets Held for Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cost related to sale of oil and gas properties			$ 21,800,000
Asset retirement obligations related to sale of oil and gas properties			19,100,000
Asset Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale of assets		$ (7,600,000)
Proceeds from sale of asset		$ 63,800,000
Area of land \| a		9,900
Asset Sale 100 Acres [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale of assets	0
Proceeds from sale of asset	$ 500,000
Area of land \| a	100
Asset Sale 150 Acres [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale of assets	$ 200,000
Proceeds from sale of asset	$ 800,000
Area of land \| a	150
Central Processing Facility and Certain Pipelines [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of conventional oil and gas properties and related equipment			36,000,000
Gain (loss) on sale of assets			4,800,000
Facility And Pipeline Sales [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of conventional oil and gas properties and related equipment			2,800,000
Gain (loss) on sale of assets			(100,000)
Pipelines [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of conventional oil and gas properties and related equipment		$ 400,000
Assets held for sale			$ 200,000
Pipelines [Member] \| Maximum [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on sale of assets		$ (100,000)