Business Acquisition Purchase Price Allocation Preliminary Estimated Of Fair Value [Abstract]

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Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Asset Retirement Obligation

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Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Mineral Rights

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Value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable to acquire the entity.

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-Publisher FASB
-Name Accounting Standards Codification
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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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- Definition

Amount of assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of liabilities due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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- Definition

The amount of property, plant, and equipment recognized as of the acquisition date.

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Costs incurred, including capitalized costs and costs charged to expense, associated with the acquisition of oil and gas properties that have proved reserves.

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Costs incurred, including capitalized costs and costs charged to expense, associated with the acquisition of oil and gas properties that have unproved reserves.

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The fair value of assets acquired in noncash investing or financing activities.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Acquisitions - Schedule of Adjustments to the Estimated Fair Value (Detail) - USD ($) $ in Thousands			12 Months Ended
	Nov. 12, 2014	Oct. 01, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consideration
Cash paid			$ 0	$ 168,978	$ 0
Allocation of Purchase Price
Mineral rights - proven oil and gas properties			0	298,627
Mineral rights - probable and possible oil and gas resources			0	40,800
Goodwill			$ 0	$ 52,012
VantaCore Partners LP
Consideration
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		$ 168,978
NRP common units		31,604
Total consideration given		200,582
Allocation of Purchase Price
Current assets		37,222
Land, property and equipment		59,946
Mineral rights		111,500
Other assets		4,347
Current liabilities		(16,953)
Asset retirement obligation		(1,005)
Goodwill		5,525
Fair value of net assets acquired		$ 200,582
Sanish Field [Member]
Consideration
Cash paid	$ 339,093
Total consideration given	339,100
Allocation of Purchase Price
Mineral rights - proven oil and gas properties	298,293
Mineral rights - probable and possible oil and gas resources	40,800
Fair value of net assets acquired	$ 339,093