Amplify Energy (AMPYW) 10-Q 7 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 31, 2013	Oct. 31, 2013	Oct. 31, 2013
		Common Units [Member]	Subordinated Units [Member]	General Partner [Member]
Document Information [Line Items]	'	'	'	'
Document Type	'10-Q	'	'	'
Amendment Flag	'false	'	'	'
Document Period End Date	30-Sep-13	'	'	'
Document Fiscal Year Focus	'2013	'	'	'
Document Fiscal Period Focus	'Q3	'	'	'
Trading Symbol	'MEMP	'	'	'
Entity Registrant Name	'MEMORIAL PRODUCTION PARTNERS LP	'	'	'
Entity Central Index Key	'0001521847	'	'	'
Current Fiscal Year End Date	'--12-31	'	'	'
Entity Filer Category	'Accelerated Filer	'	'	'
Entity Units, Units Outstanding	'	55,877,831	5,360,912	61,300

CONDENSED_CONSOLIDATED_AND_COM

CONDENSED CONSOLIDATED AND COMBINED BALANCE SHEETS (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$3,356	$7,990
Accounts receivable:	'	'
Oil and natural gas sales	22,140	17,017
Joint interest owners and other	1,271	1,427
Affiliates	3,134	8,497
Short-term derivative instruments	16,390	23,091
Escrow deposits for acquisitions	25,310	'
Prepaid expenses and other current assets	7,041	2,111
Total current assets	78,642	60,133
Property and equipment, at cost:	'	'
Oil and natural gas properties, successful efforts method	1,161,793	1,038,962
Other	1,693	1,541
Accumulated depreciation, depletion and impairment	-273,860	-178,135
Oil and natural gas properties, net	889,626	862,368
Long-term derivative instruments	27,890	11,524
Restricted investments	72,288	68,024
Other long-term assets	10,444	4,141
Total assets	1,078,890	1,006,190
Current liabilities:	'	'
Accounts payable	4,388	1,033
Accounts payable - affiliates	3,049	1,738
Revenues payable	9,050	3,108
Accrued liabilities	43,542	12,448
Short-term derivative instruments	3,184	2,635
Total current liabilities	63,213	20,962
Long-term debt (Note 8)	492,724	460,300
Asset retirement obligations	82,568	78,286
Long-term derivative instruments	5,795	9,578
Other long-term liabilities	2,059	2,100
Total liabilities	646,359	571,226
Commitments and contingencies (Note 13)	'	'
Limited partners:	'	'
Common units (39,194,060 units outstanding at September 30, 2013 and 28,921,903 units outstanding at December 31, 2012)	415,226	301,204
General partner (44,601 units outstanding at September 30, 2013 and 34,317 units outstanding at December 31, 2012)	568	450
Total partners' equity	427,050	321,810
Noncontrolling interests	5,481	5,261
Previous owners	'	107,893
Total equity	432,531	434,964
Total liabilities and equity	1,078,890	1,006,190
Subordinated Units [Member]	'	'
Limited partners:	'	'
Common units (39,194,060 units outstanding at September 30, 2013 and 28,921,903 units outstanding at December 31, 2012)	$11,256	$20,156

CONDENSED_CONSOLIDATED_AND_COM1

CONDENSED CONSOLIDATED AND COMBINED BALANCE SHEETS (Parenthetical)	Sep. 30, 2013	Dec. 31, 2012
Limited partners, units outstanding	39,194,060	28,921,903
General partner, units outstanding	44,601	34,317
Subordinated Units [Member]	'	'
Limited partners, units outstanding	5,360,912	5,360,912

CONDENSED_STATEMENTS_OF_CONSOL

CONDENSED STATEMENTS OF CONSOLIDATED AND COMBINED OPERATIONS (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:	'	'	'	'
Oil & natural gas sales	$59,194	$42,395	$160,838	$124,525
Pipeline tariff income and other	267	421	873	1,239
Total revenues	59,461	42,816	161,711	125,764
Costs and expenses:	'	'	'	'
Lease operating	14,803	14,114	40,262	39,633
Pipeline operating	394	470	1,343	1,628
Exploration	'	2	114	509
Production and ad valorem taxes	3,025	2,030	8,020	6,887
Depreciation, depletion, and amortization	16,094	13,056	45,409	36,011
Impairment of proved oil and natural gas properties	50,291	0	50,291	0
General and administrative	8,335	3,768	18,752	11,972
Accretion of asset retirement obligations	1,025	936	3,022	2,810
(Gain) loss on commodity derivative instruments	-1,443	28,427	-24,158	-10,224
(Gain) loss on sale of properties	'	'	'	-426
Other, net	'	141	'	465
Total costs and expenses	92,524	62,944	143,055	89,265
Operating income (loss)	-33,063	-20,128	18,656	36,499
Other income (expense):	'	'	'	'
Interest expense, net	-10,007	-4,163	-21,506	-11,399
Amortization of investment premium	'	-25	'	-170
Total other income (expense)	-10,007	-4,188	-21,506	-11,569
Income (loss) before income taxes	-43,070	-24,316	-2,850	24,930
Income tax benefit (expense)	-97	171	-285	-244
Net income (loss)	-43,167	-24,145	-3,135	24,686
Net income (loss) attributable to previous owners	'	1,095	-1,219	29,361
Net income (loss) attributable to noncontrolling interest	126	92	220	17
Net income (loss) attributable to partners	-43,293	-25,332	-2,136	-4,692
Allocation of net income (loss) attributable to partners:	'	'	'	'
Limited partners	-43,250	-25,307	-2,134	-4,687
General partner	($43)	($25)	($2)	($5)
Earnings per unit: (Note 10)	'	'	'	'
Basic and diluted earnings per unit	($0.97)	($1.13)	($0.05)	($0.21)
Weighted average limited partner units outstanding:	'	'	'	'
Basic and diluted	44,556	22,302	41,315	22,241

CONDENSED_STATEMENTS_OF_CONSOL1

CONDENSED STATEMENTS OF CONSOLIDATED AND COMBINED CASH FLOWS (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:	'	'
Net income (loss)	($3,135)	$24,686
Adjustments to reconcile net income (loss) to net cash provided by operating activities:	'	'
Depreciation, depletion, and amortization	45,409	36,011
Impairment of proved oil and natural gas properties	50,291	0
(Gain) loss on derivatives	-24,581	-5,593
Cash settlements on derivative instruments	11,682	29,765
Deferred income tax expense (benefit)	'	26
Amortization of deferred financing costs	3,895	828
Accretion of senior notes net discount	161	'
Amortization of investment premium	'	170
Accretion of asset retirement obligations	3,022	2,810
Amortization of equity awards	2,322	993
Gain on sale of properties	'	-426
Exploration costs	95	'
Changes in operating assets and liabilities:	'	'
Accounts receivable	396	-7,098
Prepaid expenses and other assets	-3,816	1,560
Payables and accrued liabilities	25,587	4,059
Net cash provided by operating activities	111,328	87,791
Cash flows from investing activities:	'	'
Acquisitions of oil and natural gas properties	-29,359	-129,637
Additions to oil and gas properties	-76,329	-41,717
Additions to restricted investments	-4,263	-3,651
Additions to other property and equipment	-126	-837
Escrow deposits for acquisitions	-25,310	'
Proceeds from the sale of oil and natural gas properties	'	500
Net cash used in investing activities	-135,387	-175,342
Cash flows from financing activities:	'	'
Advances on revolving credit facilities	299,000	194,000
Payments on revolving credit facilities	-664,300	-30,900
Deferred financing costs	-11,218	-411
Proceeds from the issuances of senior notes	397,563	'
Proceeds from general partner contribution	189	'
Proceeds from the issuance of common units	179,371	'
Costs incurred in conjunction with issuance of common units	-7,592	'
Distributions to partners	-62,888	-23,430
Distribution to Memorial Resource (see Note 1)	-110,700	-45,489
Distributions made by previous owners	'	-8,900
Net cash provided by financing activities	19,425	84,870
Net change in cash and cash equivalents	-4,634	-2,681
Cash and cash equivalents, beginning of period	7,990	9,624
Cash and cash equivalents, end of period	3,356	6,943
Supplemental cash flows:	'	'
Cash paid for interest	6,212	6,509
Additions to oil and gas properties - change in capital accruals	$15,858	$6,461

CONDENSED_STATEMENTS_OF_CONSOL2

CONDENSED STATEMENTS OF CONSOLIDATED AND COMBINED EQUITY (USD $)	Total	Noncontrolling Interest [Member]	Previous Owners [Member]	General Partner [Member]	Limited Partners Common [Member]	Limited Partners Subordinated [Member]
In Thousands
Beginning Balance at Dec. 31, 2012	$434,964	$5,261	$107,893	$450	$301,204	$20,156
Net income (loss)	-3,135	220	-1,219	-2	-1,938	-196
Net proceeds from the issuance of common units	171,779	'	'	'	171,779	'
Contributions	189	'	'	189	'	'
Distribution attributable to net assets acquired (Note 1)	-110,700	'	'	-111	-97,137	-13,452
Net book value of net assets acquired (Note 12)	'	'	-106,674	105	93,605	12,964
Amortization of equity awards	2,322	'	'	'	2,322	'
Distributions	-62,888	'	'	-63	-54,609	-8,216
Ending Balance at Sep. 30, 2013	$432,531	$5,481	'	$568	$415,226	$11,256

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Organization and Basis of Presentation	'
	Note 1. Organization and Basis of Presentation
	General
	Memorial Production Partners LP (the “Partnership”) is a publicly traded Delaware limited partnership, the common units of which are listed on the NASDAQ Global Market (“NASDAQ”) under the symbol “MEMP.” Unless the context requires otherwise, references to “we,” “us,” “our,” or “the Partnership” are intended to mean the business and operations of Memorial Production Partners LP and its consolidated subsidiaries.
	The Partnership was formed in April 2011 by Memorial Resource Development LLC to own, acquire and exploit oil and natural gas properties in North America. Unless the context requires otherwise, references to “Memorial Resource” refer collectively to Memorial Resource Development LLC and its subsidiaries other than the Partnership. The Partnership is owned 99.9% by its limited partners and 0.1% by its general partner, Memorial Production Partners GP LLC, which is a wholly-owned subsidiary of Memorial Resource. Our general partner is responsible for managing all of the Partnership’s operations and activities.
	We operate in one reportable segment engaged in the acquisition, exploitation, development and production of oil and natural gas properties. Our management evaluates performance based on one reportable business segment as there are not different economic environments within the operation of our oil and natural gas properties. Our business activities are conducted through Memorial Production Operating LLC (“OLLC”), our wholly-owned subsidiary, and its wholly-owned subsidiaries. Our assets consist primarily of producing oil and natural gas properties and are principally located in Texas, Louisiana and offshore Southern California. Most of our oil and natural gas properties are located in large, mature oil and natural gas reservoirs. The Partnership’s properties consist primarily of operated and non-operated working interests in producing and undeveloped leasehold acreage and working interests in identified producing wells (often referred to as wellbore assignments).
	Memorial Production Finance Corporation (“Finance Corp.”), our wholly-owned subsidiary, has no material assets or any liabilities other than as a co-issuer of our debt securities and as a guarantor of certain of our other indebtedness. Its activities will be limited to co-issuing our debt securities and engaging in other activities incidental thereto.
	Memorial Resource is a Delaware limited liability company owned and formed by Natural Gas Partners VIII, L.P., Natural Gas Partners IX, L.P. and NGP IX Offshore Holdings, L.P. (collectively, the “Funds”) to own, acquire, exploit and develop oil and natural gas properties and to own our general partner. Memorial Resource provides management, administrative, and operations personnel to us and our general partner under an omnibus agreement (see Note 12). The Funds are private equity funds managed by Natural Gas Partners (“NGP”). The Funds collectively directly own, through non-voting membership interests in our general partner, 50% of the economic interest in our incentive distribution rights (“IDRs”). The remaining economic interest in our IDRs is owned by our general partner.
	References to “the previous owners” for accounting and financial reporting purposes refer collectively to: (i) certain oil and natural gas properties the Partnership acquired from Memorial Resource in April and May 2012 for periods after common control commenced through their respective acquisition dates, (ii) Rise Energy Operating, LLC and its wholly-owned subsidiaries (except for Rise Energy Operating, Inc.) (“REO”) from February 3, 2009 (inception) through the date of acquisition; and (iii) certain oil and natural gas properties and related assets in East Texas and North Louisiana that the Partnership acquired in March 2013 (the “WHT Properties”) owned by WHT Energy Partners LLC (“WHT”) from February 2, 2011 (inception) through the date of acquisition. Each of these acquisitions was accounted for as a transaction between entities under common control, similar to a pooling of interests, whereby the net assets acquired were recorded at historical cost and certain financial and other information has been retrospectively revised to give effect to such acquisitions as if the Partnership owned the assets for periods after common control commenced through their respective acquisition dates. The WHT Properties represent additional working interests in properties that we originally acquired in December 2011 in conjunction with our initial public offering. See Note 12 for additional information regarding these common control transactions.
	Basis of Presentation
	Our consolidated results of operations are presented together with the combined results of operations pertaining to the previous owners. The combined financial statements of the previous owners were derived from their historical accounting records and reflect their historical financial position, results of operations and cash flows.
	The ownership interest of the noncontrolling shareholder in the San Pedro Bay Pipeline Company (“SPBPC”), an indirect majority-owned subsidiary of the Partnership, is presented as a noncontrolling interest in the financial statements.
	Our results of operations for the three and nine months ended September 30, 2013 are not necessarily indicative of results expected for the full year. In our opinion, the accompanying unaudited condensed consolidated and combined financial statements include all adjustments of a normal recurring nature necessary for fair presentation. Although we believe the disclosures in these financial statements are adequate and make the information presented not misleading, certain information and footnote disclosures normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”). These unaudited condensed consolidated and combined financial statements and the notes thereto should be read in conjunction with the recast audited consolidated and combined financial statements and notes thereto included in our Current Report on Form 8-K filed on June 19, 2013 (our “Recast Form 8-K”). On October 1, 2013, we filed a Current Report on Form 8-K, which included audited supplemental financial statements that retrospectively revised certain of our financial and other information to give effect to the Cinco Group acquisition (see Note 12). This Quarterly Report on Form 10-Q has not been recast for the Cinco Group acquisition which closed on October 1, 2013.
	All material intercompany transactions and balances have been eliminated in preparation of our consolidated and combined financial statements.
	Use of Estimates
	The preparation of the accompanying unaudited condensed consolidated and combined financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated and combined financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	Significant estimates include, but are not limited to, oil and natural gas reserves; depreciation, depletion, and amortization of proved oil and natural gas properties; future cash flows from oil and natural gas properties; impairment of long-lived assets; fair value of derivatives; fair value of equity compensation; fair values of assets acquired and liabilities assumed in business combinations and asset retirement obligations.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	Note 2. Summary of Significant Accounting Policies
	A discussion of our critical accounting policies and estimates is included in our Recast Form 8-K.
	Current Liabilities
	Current accrued liabilities consisted of the following at the dates indicated (in thousands):
		September 30,		December 31,
		2013		2012
	Accrued capital expenditures	$	20,600	$	4,742
	Accrued lease operating expense		4,966		3,944
	Accrued interest payable(1)		13,994		618
	Accrued ad valorem		3,073		341
	Other		909		2,803
		$	43,542	$	12,448
	(1)    Increase in accrued interest payable primarily due to issuances of Senior Notes (see Note 8).
	New Accounting Pronouncements
	Offsetting Disclosure Requirements. In December 2011, the FASB issued an accounting standard update intended to enhance current disclosure requirements on offsetting financial assets and liabilities. In January 2013, the FASB issued an accounting standard update to clarify the scope of offsetting disclosure requirements. The disclosure requirements require the disclosure of both gross and net information about derivatives, repurchase agreements and reverse purchase agreements, and securities borrowing and securities lending transactions eligible for offset on the balance sheet or subject to a master netting arrangement or similar agreement. Disclosure of collateral received and posted in connection with master netting agreements or similar arrangements is also required. We adopted this guidance on January 1, 2013 and applied the disclosure requirements retrospectively. The enhanced offsetting disclosure requirements did not have a significant impact on our financial statements.
	Other accounting standards that have been issued by the FASB or other standards-setting bodies are not expected to have a material impact on the Partnership’s financial position, results of operations and cash flows.

Acquisitions_and_Divestitures

Acquisitions and Divestitures	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Acquisitions and Divestitures	'
	Note 3. Acquisitions and Divestitures
	Related Party. See Note 12 for further information regarding related party acquisitions that have been accounted for as transactions between entities under common control that impact the basis of presentation for the periods presented.
	Third Party. We closed two separate transactions during the three and nine months ended September 30, 2013 to acquire certain oil and natural gas properties from third parties in East Texas (the “East Texas Acquisition”) and the Rockies (the “Rockies Acquisition”) for approximately $29.0 million in aggregate, subject to customary post-closing adjustments. The East Texas Acquisition closed on September 6, 2013 and the Rockies Acquisition closed on August 30, 2013. The following table summarizes our preliminary purchase price allocations as of each acquisition date (in thousands):
		East Texas		Rockies
		Acquisition		Acquisition
	Oil and gas properties	$	9,974	$	20,744
	Asset retirement obligations		(78)		(1,163)
	Accrued liabilities		--		(118)
	Total identifiable net assets	$	9,896	$	19,463
	On May 1, 2012, we acquired non-operating interests in certain oil and natural gas properties located in East Texas and North Louisiana from an undisclosed third party seller for a final net purchase price of approximately $36.5 million after customary post-closing adjustments.
	Acquisition-related costs. Acquisition-related costs for both related party and third party transactions are included in general and administrative expenses in the accompanying statements of operations for the periods indicated below (in thousands):
	For the Three Months			For the Nine Months
	Ended September 30,			Ended September 30,
	2013	2012		2013		2012
	$                    2,310	$	381	$	3,422	$	780
	Disclosure of Supplementary Pro Forma Information for Business Combinations. In May and September 2012, we closed two third-party acquisitions. The following unaudited pro forma combined results of operations are provided for the three and nine months ended September 30, 2012 as though these third-party acquisitions had been completed on January 1, 2011. The unaudited pro forma financial information was derived from the historical combined statements of operations of the Partnership and the previous owners and was adjusted to include: (i) the revenues and direct operating expenses associated with oil and gas properties acquired, (ii) depletion expense applied to the adjusted basis of the properties acquired and (iii) interest expense on additional borrowings necessary to finance the acquisitions. The unaudited pro forma financial information does not purport to be indicative of results of operations that would have occurred had the transactions occurred on the basis assumed above, nor is such information indicative of expected future results of operations.
		For the Three Months		For the Nine Months
		Ended September 30,		Ended September 30,
		2012		2012
		(In thousands, except per unit amounts)
	Revenues	$	47,634	$	146,777
	Net income (loss)		(22,455)		33,140
	Basic and diluted earnings per unit		(1.06)		0.17

Fair_Value_Measurements_of_Fin

Fair Value Measurements of Financial Instruments	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Fair Value Measurements of Financial Instruments	'
	Note 4. Fair Value Measurements of Financial Instruments
	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at a specified measurement date. Fair value estimates are based on either (i) actual market data or (ii) assumptions that other market participants would use in pricing an asset or liability, including estimates of risk. A three-tier hierarchy has been established that classifies fair value amounts recognized or disclosed in the financial statements. The hierarchy considers fair value amounts based on observable inputs (Levels 1 and 2) to be more reliable and predictable than those based primarily on unobservable inputs (Level 3). All of the derivative instruments reflected on the accompanying balance sheets were considered Level 2.
	The carrying values of accounts receivables, accounts payables (including accrued liabilities) and amounts outstanding under long-term debt agreements with variable rates included in the accompanying balance sheets approximated fair value at September 30, 2013 and December 31, 2012. The fair value estimates are based upon observable market data and are classified within Level 2 of the fair value hierarchy. These assets and liabilities are not presented in the following tables. See Note 8 for the estimated fair value of our outstanding fixed-rate debt.
	Assets and Liabilities Measured at Fair Value on a Recurring Basis
	The fair market values of the derivative financial instruments reflected on the balance sheets as of September 30, 2013 and December 31, 2012 were based on estimated forward commodity prices and forward interest rate yield curves. Financial assets and liabilities are classified based on the lowest level of input that is significant to the fair value measurement in its entirety. The significance of a particular input to the fair value measurement requires judgment, and may affect the valuation of the fair value of assets and liabilities and their placement within the fair value hierarchy levels. The following table presents the gross derivative assets and liabilities that are measured at fair value on a recurring basis at September 30, 2013 and December 31, 2012 for each of the fair value hierarchy levels:
			Fair Value Measurements at September 30, 2013 Using
			Quoted Prices in		Significant Other		Significant		Fair Value
			Active Market		Observable Inputs		Unobservable Inputs
			(Level 1)		(Level 2)		(Level 3)
			(In thousands)
	Assets:
	Commodity derivatives		$	--	$	87,487	$	--	$	87,487
	Liabilities:
	Commodity derivatives		$	--	$	48,450	$	--	$	48,450
	Interest rate derivatives			--		3,736		--		3,736
	Total liabilities		$	--	$	52,186	$	--	$	52,186
			Fair Value Measurements at December 31, 2012 Using
			Quoted Prices in		Significant Other		Significant		Fair Value
			Active Market		Observable Inputs		Unobservable Inputs
			(Level 1)		(Level 2)		(Level 3)
			(In thousands)
	Assets:
	Commodity derivatives		$	--	$	69,303	$	--	$	69,303
	Liabilities:
	Commodity derivatives		$	--	$	41,814	$	--	$	41,814
	Interest rate derivatives			--		5,087		--		5,087
	Total liabilities		$	--	$	46,901	$	--	$	46,901
	See Note 5 for additional information regarding our derivative instruments.
	Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
	Certain assets and liabilities are reported at fair value on a nonrecurring basis as reflected on the balance sheets. The following methods and assumptions are used to estimate the fair values:
		•		The fair value of asset retirement obligations (“AROs”) is based on discounted cash flow projections using numerous estimates, assumptions, and judgments regarding factors such as the existence of a legal obligation for an ARO; amounts and timing of settlements; the credit-adjusted risk-free rate; and inflation rates. See Note 6 for a summary of changes in AROs.
		•		If sufficient market data is not available, the determination of the fair values of proved and unproved properties acquired in transactions accounted for as business combinations are prepared by utilizing estimates of discounted cash flow projections. The factors to determine fair value include, but are not limited to, estimates of: (i) economic reserves; (ii) future operating and development costs; (iii) future commodity prices; and (iv) a market-based weighted average cost of capital.
		•		Proved oil and natural gas properties are reviewed for impairment when events and circumstances indicate a possible decline in the recoverability of the carrying value of such properties. The factors used to determine fair value include, but are not limited to, estimates of proved reserves, future commodity prices, the timing of future production and capital expenditures and a discount rate commensurate with the risk reflective of the lives remaining for the respective oil and gas properties.
	During three and nine months ended September 30, 2013, we recognized $50.3 million of impairments. The impairments related to certain properties located in East Texas. The estimated future cash flows expected from these properties were compared to their carrying values and determined to be unrecoverable as a result of a downward revision of estimated proved reserves based on updated well performance data. The carrying value of these properties after impairment was approximately $31.5 million. We did not have any impairment charges for 2012.

Risk_Management_and_Derivative

Risk Management and Derivative Instruments	9 Months Ended
	Sep. 30, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]	'
Risk Management and Derivative Instruments	'
	Note 5. Risk Management and Derivative Instruments
	Derivative instruments are utilized to manage exposure to commodity price and interest rate fluctuations and achieve a more predictable cash flow in connection with natural gas and oil sales from production and borrowing related activities. These instruments limit exposure to declines in prices or increases in interest rates, but also limit the benefits that would be realized if prices increase or interest rates decrease.
	Certain inherent business risks are associated with commodity and interest derivative contracts, including market risk and credit risk. Market risk is the risk that the price of natural gas or oil will change, either favorably or unfavorably, in response to changing market conditions. Credit risk is the risk of loss from nonperformance by the counterparty to a contract. It is our policy to enter into derivative contracts, including interest rate swaps, only with counterparties that are creditworthy financial institutions deemed by management as competent and competitive market makers. Each of the counterparties to our derivative contracts is a lender under our credit agreement. While collateral is generally not required to be posted by counterparties, credit risk associated with derivative instruments is minimized by limiting exposure to any single counterparty and entering into derivative instruments only with counterparties that are large financial institutions. Additionally, master netting agreements are used to mitigate risk of loss due to default with counterparties on derivative instruments. We have also entered into the International Swaps and Derivatives Association Master Agreements (“ISDA Agreements”) with each of our counterparties. The terms of the ISDA Agreements provide us and each of our counterparties with rights of set-off upon the occurrence of defined acts of default by either us or our counterparty to a derivative, whereby the party not in default may set-off all liabilities owed to the defaulting party against all net derivative asset receivables from the defaulting party. As a result, had certain counterparties failed completely to perform according to the terms of the existing contracts, we would have the right to offset $25.5 million against amounts outstanding under our revolving credit facility at September 30, 2013, reducing our maximum credit exposure to approximately $18.8 million, of which approximately $11.6 million was with a single counterparty. See Note 8 for additional information regarding our revolving credit facility.
	Commodity Derivatives
	We may use a combination of commodity derivatives (e.g., floating-for-fixed swaps, costless collars, call spreads and basis swaps) to manage exposure to commodity price volatility. Historically, the Partnership has not paid or received premiums for put options. We enter into natural gas derivative contracts that are indexed to NYMEX Henry Hub and regional indices such as NGPL TXOK, TETCO STX, and Houston Ship Channel in proximity to our areas of production. We also enter into oil derivative contracts indexed to NYMEX WTI, Inter-Continental Exchange (“ICE”) Brent and California Midway-Sunset. Our NGL derivative contracts are indexed to OPIS Mont Belvieu. At September 30, 2013, we had the following open commodity positions:
			Remaining				2014				2015			2016				2017		2018		2019
			2013
	Natural Gas Derivative Contracts:
	Fixed price swap contracts:
	Average Monthly Volume (MMBtu)			1,345,172				1,860,458				1,785,278			1,842,442				1,690,067		1,660,000		1,514,583
	Weighted-average fixed price		$	4.32			$	4.34			$	4.3		$	4.47			$	4.33	$	4.58	$	4.87
	Collar contracts:
	Average Monthly Volume (MMBtu)			840,000				300,000				200,000			--				--		--		--
	Weighted-average floor price		$	4.82			$	5.08			$	5.25		$	--			$	--	$	--	$	--
	Weighted-average ceiling price		$	5.88			$	6.31			$	6.75		$	--			$	--	$	--	$	--
	Call spreads (1):
	Average Monthly Volume (MMBtu)			430,000				120,000				80,000			--				--		--		--
	Weighted-average sold strike price		$	4.59			$	5.08			$	5.25		$	--			$	--	$	--	$	--
	Weighted-average bought strike price		$	5.84			$	6.31			$	6.75		$	--			$	--	$	--	$	--
	Basis swaps:
	Average Monthly Volume (MMBtu)			1,620,932				2,224,583				--			--				--		--		--
	Spread		$	-0.1			$	-0.09			$	--		$	--			$	--	$	--	$	--
	Crude Oil Derivative Contracts:
	Fixed price swap contracts:
	Average Monthly Volume (Bbls)			73,632				78,477				96,281			116,013				105,500		100,000		--
	Weighted-average fixed price		$	102.53			$	97.4			$	93.72		$	86.97			$	85.84	$	85.34	$	--
	Collar contracts:
	Average Monthly Volume (Bbls)			10,600				8,000				--			--				--		--		--
	Weighted-average floor price		$	88.87			$	90			$	--		$	--			$	--	$	--	$	--
	Weighted-average ceiling price		$	118.59			$	117.72			$	--		$	--			$	--	$	--	$	--
	Basis swaps:
	Average Monthly Volume (Bbls)			40,000				49,958				47,500			--				--		--		--
	Spread		$	-10.2			$	-9.04			$	-9.6		$	--			$	--	$	--	$	--
	NGL Derivative Contracts:
	Fixed price swap contracts:
	Average Monthly Volume (Bbls)			94,871				84,150				85,300			--				--		--		--
	Weighted-average fixed price		$	39.49			$	39.76			$	35.12		$	--			$	--	$	--	$	--
	-1	These transactions were entered into for the purpose of eliminating the ceiling portion of certain collar arrangements, which effectively converted the applicable collars into swaps.
	Interest Rate Swaps
	Periodically, we enter into interest rate swaps to mitigate exposure to market rate fluctuations by converting variable interest rates such as those in our credit agreement to fixed interest rates. In connection with the issuances of senior notes in April and May 2013 (see Note 8), we entered into offsetting interest rate swap derivative instruments to avoid being economically over-hedged. At September 30, 2013, we had the following interest rate swap open positions:
	Period Covered		Notional				Floating Rate		Fixed Rate				Fixed Rate Payer
			($ in thousands)
	April 2011 to April 2014 (1)		$	75,000			1 Month LIBOR			1.51	%		Partnership
	April 2013 to October 2013		$	75,000			1 Month LIBOR			1.51	%		Counterparty
	January 2013 to December 2016		$	100,000			1 Month LIBOR			1.305	%		Partnership
	April 2013 to October 2013		$	40,000			1 Month LIBOR			1.305	%		Counterparty
	January 2013 to December 2016		$	50,000			1 Month LIBOR			0.97	%		Partnership
	October 2013 to April 2014		$	40,000			1 Month LIBOR			1.37	%		Partnership
	April 2014 to October 2014		$	75,000			1 Month LIBOR			1.64	%		Partnership
	June 2013 to October 2013		$	110,000			1 Month LIBOR			1.153	%		Counterparty
	October 2014 to February 2015		$	110,000			1 Month LIBOR			1.4	%		Partnership
		(1)	These interest rate swaps were novated to the Partnership from the previous owners in connection with the March 2013 acquisition.
	Subsequent event. In October 2013, we entered into offsetting interest rate swap derivative instruments to avoid being economically over-hedged. We will receive the fixed rate and will pay the floating rate as follows:
	Period Covered		Notional				Floating Rate		Fixed Rate				Fixed Rate Payer
			($ in thousands)
	October 2013 to April 2014		$	150,000			1 Month LIBOR			1.193	%		Counterparty
	October 2013 to April 2014		$	75,000			1 Month LIBOR			1.51	%		Counterparty
	February 2015 to August 2015		$	225,000			1 Month LIBOR			1.715	%		Partnership
	Balance Sheet Presentation
	The following table summarizes both: (i) the gross fair value of derivative instruments by the appropriate balance sheet classification even when the derivative instruments are subject to netting arrangements and qualify for net presentation in the balance sheet and (ii) the net recorded fair value as reflected on the balance sheet at September 30, 2013 and December 31, 2012. There was no cash collateral received or pledged associated with our derivative instruments since each of the counterparties to our derivative contracts is a lender under our credit agreement.
							Asset Derivatives							Liability Derivatives
							September 30,				December 31,			September 30,				December 31,
	Type		Balance Sheet Location				2013				2012			2013				2012
						(In thousands)
Natural gas contracts			Short-term derivative instruments			$	18,714			$	22,069		$	582			$	961
Oil contracts			Short-term derivative instruments				3,469				6,453			6,102				4,483
NGL contracts			Short-term derivative instruments				1,722				871			1,515				1,124
Interest rate swaps			Short-term derivative instruments				--				--			2,500				2,369
Gross fair value							23,905				29,393			10,699				8,937
Netting arrangements			Short-term derivative instruments				(7,515)				(6,302)			(7,515)				(6,302)
Net recorded fair value			Short-term derivative instruments			$	16,390			$	23,091		$	3,184			$	2,635
Natural gas contracts			Long-term derivative instruments			$	30,067			$	17,435		$	6,055			$	9,352
Oil contracts			Long-term derivative instruments				32,663				22,471			32,989				25,360
NGL contracts			Long-term derivative instruments				852				4			1,207				534
Interest rate swaps			Long-term derivative instruments				--				--			1,236				2,718
Gross fair value							63,582				39,910			41,487				37,964
Netting arrangements			Long-term derivative instruments				(35,692)				(28,386)			(35,692)				(28,386)
Net recorded fair value			Long-term derivative instruments			$	27,890			$	11,524		$	5,795			$	9,578
(Gains) Losses on Derivatives
We do not designate derivative instruments as hedging instruments for accounting and financial reporting purposes and neither did the previous owners. Accordingly, all gains and losses, including changes in the derivative instruments’ fair values, have been recorded in the accompanying statements of operations. The following table details the gains and losses related to derivative instruments for the three and nine months ended September 30, 2013 and 2012 (in thousands):
				For the Three Months											For the Nine Months
				Ended September 30,											Ended September 30,
Statements of				2013						2012					2013				2012
Operations Location
Commodity derivative contracts		(Gain) loss on commodity derivatives		$	(1,443)					$	28,427				$	(24,158)			$	(10,224)
Interest rate derivatives		Interest expense			1,022						1,604					-423				4,631

Asset_Retirement_Obligations

Asset Retirement Obligations	9 Months Ended
	Sep. 30, 2013
Asset Retirement Obligation Disclosure [Abstract]	'
Asset Retirement Obligations	'
	Note 6. Asset Retirement Obligations
	The Partnership’s asset retirement obligations primarily relate to the Partnership’s portion of future plugging and abandonment costs for wells and related facilities. The following table presents the changes in the asset retirement obligations for the nine months ended September 30, 2013 (in thousands):
	Asset retirement obligations at beginning of period	$	78,286
	Liabilities added from acquisitions or drilling		1,278
	Liabilities removed upon plugging and abandoning		(18)
	Accretion expense		3,022
	Asset retirement obligations at end of period	$	82,568

Restricted_Investments

Restricted Investments	9 Months Ended
	Sep. 30, 2013
Text Block [Abstract]	'
Restricted Investments	'
	Note 7. Restricted Investments
	Various restricted investment accounts fund certain long-term contractual and regulatory asset retirement obligations and collateralize certain regulatory bonds associated with our offshore Southern California oil and gas properties. The components of the restricted investment balance consisted of the following at the dates indicated:
		September 30,		December 31,
		2013		2012
		(In thousands)
	BOEM platform abandonment (See Note 13)	$	65,390	$	61,389
	BOEM lease bonds		776		776
	SPBPC Collateral:
	Contractual pipeline and surface facilities abandonment		2,222		1,959
	California State Lands Commission pipeline right-of-way bond		3,000		3,000
	City of Long Beach pipeline facility permit		500		500
	Federal pipeline right-of-way bond		300		300
	Port of Long Beach pipeline license		100		100
	Restricted investments	$	72,288	$	68,024

Long_Term_Debt

Long Term Debt	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Long Term Debt	'
	Note 8. Long Term Debt
	The following table presents our consolidated and combined debt obligations at the dates indicated:
			September 30,		December 31,
			2013		2012
			(In thousands)
	OLLC $1.0 billion multi-year revolving credit facility, variable-rate, due March 2018		$	95,000	$	371,000
	7.625% senior notes, fixed-rate, due May 1, 2021 (1)			400,000		--
	WHT $400.0 million revolving credit facility, variable-rate, terminated March 2013			--		89,300
	Unamortized discounts			(2,276)		--
	Total long-term debt		$	492,724	$	460,300
		-1	The estimated fair value of our fixed-rate debt was $386.0 million. The estimated fair value is based on quoted market prices and is classified as Level 1 within the fair value hierarchy.
	Subsidiary Guarantors
	We filed a universal shelf registration statement with the SEC, which was declared effective on March 15, 2013, that allows us to issue up to $750.0 million in debt and equity securities. Any debt securities issued will be governed by an indenture. Furthermore, any debt securities issued may be jointly and severally, fully and unconditionally guaranteed (subject to customary release provisions) by certain of the Partnership’s subsidiaries (collectively, the “Guarantor Subsidiaries”). The Guarantor Subsidiaries are 100% owned by the Partnership. The Partnership has no material assets or operations independent of the Guarantor Subsidiaries and there are no significant restrictions upon the ability of the Guarantor Subsidiaries to distribute funds to the Partnership.
	Borrowing Base
	Credit facilities tied to borrowing bases are common throughout the oil and gas industry. The borrowing base for each credit facility was the following at the dates indicated:
			September 30,		December 31,
			2013		2012
			(In thousands)
	OLLC $1.0 billion multi-year revolving credit facility, variable-rate, due March 2018		$	480,000	$	460,000
	WHT $400.0 million revolving credit facility, variable-rate, terminated March 2013			--		120,000
	Total borrowing base		$	480,000	$	580,000
	The borrowing base increased to $580.0 million effective March 28, 2013. The borrowing base was then automatically reduced by $100.0 million in conjunction with the issuances of senior notes in April and May 2013 in accordance with the terms of our credit facility. Effective October 1, 2013, the borrowing base was increased by $440.0 million, as discussed below. On October 10, 2013, the borrowing base was automatically reduced by $75.0 million in conjunction with the issuance of additional senior notes, as discussed below.
	OLLC Revolving Credit Facility
	OLLC entered into a $1.0 billion revolving credit facility at the closing of our initial public offering, which is guaranteed by us and certain of our current and future subsidiaries. On September 26, 2013, we entered into a sixth amendment to our credit agreement, which among other things: (i) increased the maximum aggregate credit amounts under the revolving facility from $1.0 billion to $2.0 billion and (ii) increased the borrowing base from $480.0 million to $920.0 million upon the closing of the Cinco Group acquisition on October 1, 2013 as further discussed in Note 12.
	WHT Revolving Credit Facility
	WHT entered into a $400.0 million revolving credit facility on April 8, 2011 with a maturity date of April 8, 2016. On March 28, 2013, the debt balance then outstanding under the revolving credit facility of $89.3 million and all accrued interest was paid off in full and the revolving credit facility was terminated.
	REO Revolving Credit Facility
	On October 26, 2011, REO entered into a three-year, $150.0 million revolving credit facility. On December 12, 2012, indebtedness then outstanding under the revolving credit facility of $28.5 million and all accrued interest was paid off in full and the revolving credit facility was terminated.
	7.625% Senior Notes
	On April 17, 2013, we and Finance Corp. (collectively, the “Issuers”) completed a private placement of $300.0 million aggregate principal amount of 7.625% senior unsecured notes due 2021 (the “Senior Notes”). The Senior Notes were issued at 98.521% of par and are fully and unconditionally guaranteed (subject to customary release provisions) on a joint and several basis by the Guarantor Subsidiaries and by certain future subsidiaries of the Partnership. On May 23, 2013, the Issuers issued an additional $100.0 million aggregate principal amount of the Senior Notes at 102.0% of par. On October 10, 2013, the Issuers issued an additional $300.0 million aggregate principal amount of the Senior Notes at 97.0% of par. The Senior Notes will mature on May 1, 2021 with interest accruing at a rate of 7.625% per annum and payable semi-annually in arrears on May 1 and November 1 of each year, commencing November 1, 2013. The Senior Notes are governed by an indenture. The Senior Notes are subject to optional redemption at prices specified in the indenture plus accrued and unpaid interest, if any. The Issuers may also be required to repurchase the Senior Notes upon a change of control. The indenture contains customary covenants and restrictive provisions, many of which will terminate if at any time no default exists under the indenture and the Senior Notes receive an investment grade rating from both of two specified ratings agencies. The indenture also provides for customary and other events of default. In the case of an event of default arising from certain events of bankruptcy or insolvency with respect to either of the Issuers, all outstanding Senior Notes will become due and payable immediately without further action or notice. If any other event of default occurs and is continuing, the trustee or the holders of at least 25% in principal amount of the then outstanding Senior Notes may declare all the Senior Notes to be due and payable immediately.
	Weighted-Average Interest Rates
	The following table presents the weighted-average interest rates paid on our consolidated and combined variable-rate debt obligations for the periods presented:
			For the Three Months								For the Nine Months
			Ended September 30,								Ended September 30,
			2013				2012				2013		2012
	OLLC revolving credit facility			2.13%				2.79%				2.55%		2.79%
	WHT revolving credit facility			n/a				2.88%				2.29%		2.81%
	REO revolving credit facility			n/a				3.19%				n/a		3.31%
	Unamortized Deferred Financing Costs
	Unamortized deferred financing costs associated with our consolidated and combined debt obligations were as follows at the dates indicated:
			September 30,		December 31,
			2013		2012
			(In thousands)
	OLLC $1.0 billion multi-year revolving credit facility, variable-rate, due March 2018 (1)		$	3,542	$	3,359
	Senior Notes (2)			8,871		--
	WHT $400.0 million revolving credit facility, variable-rate, terminated March 2013 (3)			--		1,419
		-1	Additional financing costs were incurred in connection with the borrowing base increase that became effective March 28, 2013. Unamortized deferred financing costs are amortized over the remaining life of our revolving credit facility. As disclosed above, the borrowing base was automatically reduced upon issuance of the Senior Notes. As a result, approximately $0.9 million of deferred financing costs were written-off during the nine months ended September 30, 2013 and are included in interest expense in the accompanying statements of operations.
		-2	Unamortized deferred financing costs are amortized using the straight line method which approximates the effective interest method.
		-3	The unamortized deferred financing costs were written-off at the time the debt was repaid and the facility was terminated on March 28, 2013.
	Advances and Repayments
	The following table presents borrowings and repayments under our consolidated and combined revolving credit facilities for the periods presented (in thousands):
			OLLC Revolving		WHT Revolving				REO Revolving		Total
			Credit Facility		Credit Facility				Credit Facility
	For the Nine Months Ended September 30, 2013:
	Advances on revolving credit facility		$	298,000	$	1,000			$	--	$	299,000
	Payments on revolving credit facility			(574,000)		(90,300)				--		(664,300)
	For the Nine Months Ended September 30, 2012:
	Advances on revolving credit facility		$	186,000	$	1,000			$	7,000	$	194,000
	Payments on revolving credit facility			-13,000		-5,900				(12,000)		-30,900

Equity_Distributions

Equity & Distributions	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
Equity & Distributions	'
	Note 9. Equity & Distributions
	2013 Public Equity Offerings
	On March 25, 2013, we issued 9,775,000 common units representing limited partner interests in the Partnership (including 1,275,000 common units purchased pursuant to the full exercise of the underwriters’ option to purchase additional common units) to the public at an offering price of $18.35 per unit generating total net proceeds of approximately $171.8 million after deducting underwriting discounts and offering expenses. The net proceeds from this equity offering, including our general partner’s proportionate capital contribution, partially funded the acquisition of all of the outstanding equity interests in WHT as further discussed under Note 12.
	See Note 14 for additional information regarding our October 2013 public equity offering.
	Equity Outstanding
	The following table summarizes changes in the number of outstanding units since December 31, 2012:
			Common			Subordinated				General
										Partner
	Balance December 31, 2012			28,921,903			5,360,912				34,317
	Common units issued			9,775,000			--				--
	Restricted common units issued			515,947			--				--
	Restricted common units forfeited			(11,734)			--				--
	Restricted common units repurchased (1)			(7,056)			--				--
	General partner units issued			--			--				10,284
	Balance September 30, 2013			39,194,060			5,360,912				44,601
		-1	Restricted common units are generally net-settled by unitholders to cover the required withholding tax upon vesting. Unitholders surrendered units with value equivalent to the employees’ minimum statutory obligation for the applicable income and other employment taxes. Total payments remitted for the employees’ tax obligations to the appropriate taxing authorities were $0.1 million. These net-settlements had the effect of unit repurchases by the Partnership as they reduced the number of units that would have otherwise been outstanding as a result of the vesting and did not represent an expense to the Partnership.
	Restricted common units are a component of common units as presented on our unaudited condensed consolidated balance sheets. See Note 11 for additional information regarding restricted common units that were granted during the nine months ended September 30, 2013.
	As of September 30, 2013, Memorial Resource owned approximately 18.0% of the common units and 100% of the subordinated units. Memorial Resource owns all of the voting interests in our general partner and 50% of the economic interest in our IDRs. The Funds collectively directly own, through non-voting membership interests in our general partner, the remaining 50% economic interest in our IDRs.
	Allocations of Net Income (Loss)
	Net income (loss) attributable to the Partnership is allocated between our general partner and the common and subordinated unitholders in proportion to their pro rata ownership after giving effect to priority earnings allocations in an amount equal to incentive cash distributions allocated to our general partner. Net income (loss) attributable to acquisitions accounted for as a transaction between entities under common control prior to their acquisition date is allocated to the previous owners.
	Cash Distributions to Unitholders
	The following table summarizes our declared quarterly cash distribution rates with respect to the quarter indicated (dollars in millions, except per unit amounts):
	Quarter		Declaration Date		Record Date	Payable Date		Amount				Aggregate		Memorial
								Per Unit (1)				Distribution (2)		Resource
														Distribution
	3rd Quarter 2013		October 22, 2013		November 1, 2013	November 12, 2013		$	0.55			$	33.8	$	6.9
	2nd Quarter 2013		18-Jul-13		1-Aug-13	12-Aug-13		$	0.5125			$	22.9	$	6.4
	1st Quarter 2013		18-Apr-13		1-May-13	13-May-13		$	0.5125			$	22.6	$	6.4
	4th Quarter 2012		15-Jan-13		1-Feb-13	13-Feb-13		$	0.5075			$	17.4	$	6.3
	3rd Quarter 2012		19-Oct-12		1-Nov-12	12-Nov-12		$	0.495			$	11.1	$	6.2
	2nd Quarter 2012		19-Jul-12		1-Aug-12	13-Aug-12		$	0.48			$	10.7	$	6.0
	1st Quarter 2012		19-Apr-12		1-May-12	14-May-12		$	0.48			$	10.7	$	6.0
	4th Quarter 2011		26-Jan-12		6-Feb-12	13-Feb-12		$	0.0929			$	2	$	1.2
	(1)	The $0.0929 per unit pro-rated distribution paid on February 13, 2012 was based upon the minimum quarterly distribution of $0.4750 per unit adjusted to take into account the 18-day period of the fourth quarter of 2011 during which the Partnership was a public entity.
	(2)	The aggregate distribution for the third quarter of 2013 reflects the October 2013 public equity offering (see Note 14).

Earnings_per_Unit

Earnings per Unit	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Earnings per Unit	'
	Note 10. Earnings per Unit
	The following sets forth the calculation of earnings (loss) per unit, or EPU, for the periods indicated (in thousands, except per unit amounts):
		For the		For the		For the		For the
		Three Months		Three Months		Nine Months		Nine Months
		Ended		Ended		Ended		Ended
		September 30,		September 30,		September 30,		September 30,
		2013		2012		2013		2012
	Net income (loss) attributable to partners	$	(43,293)	$	(25,332)	$	(2,136)	$	(4,692)
	Less: General partner’s 0.1% interest in net income (loss)		(43)		(25)		(2)		(5)
	Less: IDRs		(40)		--		(40)		--
	Net income (loss) available to limited partners	$	(43,210)	$	(25,307)	$	(2,094)	$	(4,687)
	Weighted average limited partner units outstanding:
	Common units		39,195		16,941		35,954		16,880
	Subordinated units		5,361		5,361		5,361		5,361
	Total		44,556		22,302		41,315		22,241
	Basic and diluted EPU	$	(0.97)	$	(1.13)	$	(0.05)	$	(0.21)

Equitybased_Awards

Equity-based Awards	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Equity-based Awards	'
	Note 11. Equity-based Awards
	The following table summarizes information regarding restricted common unit awards granted under the Memorial Production Partners GP LLC Long-Term Incentive Plan (“LTIP”) for the periods presented:
			Number of Units		Weighted-
					Average Grant
					Date Fair Value
					per Unit (1)
	Restricted common units outstanding at December 31, 2012			285,609	$	18.08
	Granted (2)			515,947	$	18.81
	Forfeited			(11,734)	$	17.24
	Vested			(91,154)	$	18.31
	Restricted common units outstanding at September 30, 2013			698,668	$	18.6
		-1	Determined by dividing the aggregate grant date fair value of awards by the number of awards issued.
		-2	The aggregate grant date fair value of restricted common unit awards issued in 2013 was $9.7 million based on grant date market prices ranging from of $18.33 to $19.88 per unit.
	The following table summarizes the amount of recognized compensation expense associated with these awards that are reflected in the accompanying statements of operations for the periods presented (in thousands):
			For the Three Months						For the Nine Months
			Ended September 30,						Ended September 30,
			2013				2012		2013		2012
			$	1,237			$	418	$	2,322	$	993
	The unrecognized compensation cost associated with restricted common unit awards was $11.3 million at September 30, 2013. We expect to recognize the unrecognized compensation cost for these awards over a weighted-average period of 2.39 years. Since the restricted common units are participating securities, distributions received by the restricted common unitholders are generally included in distributions to partners as presented on our unaudited condensed statements of consolidated and combined cash flows.

Related_Party_Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2013
Related Party Transactions [Abstract]	'
Related Party Transactions	'
	Note 12. Related Party Transactions
	Amounts due to (due from) Memorial Resource and certain of its subsidiaries at September 30, 2013 and December 31, 2012 are presented as “Accounts receivable – affiliates” and “Accounts payable – affiliates” in the accompanying balance sheets.
	The following table summarizes the amount of related party transactions reflected in the accompanying statements of operations for the periods presented (in thousands):
		For the Three Months				For the Nine Months
		Ended September 30,				Ended September 30,
		2013		2012		2013		2012
		$	3,151	$	1,614	$	7,880	$	4,747
	These costs and expenses, the vast majority of which are general and administrative, represent payments under our omnibus agreement (as discussed below) and management fees paid to affiliates for operating our assets.
	Common Control Acquisitions
	October 2013 Acquisition. On October 1, 2013, we acquired, through equity and asset transactions, oil and natural gas properties primarily in the Permian Basin, East Texas and the Rockies from Memorial Resource and certain affiliates of NGP for an aggregate purchase price of approximately $603 million, subject to customary post-closing adjustments. We refer to this transaction as the “Cinco Group acquisition.” The Cinco Group acquisition was funded with borrowings under our revolving credit facility. Terms of the transaction were approved by our general partner’s board of directors and by its conflicts committee, which is comprised entirely of independent directors. The Cinco Group acquisition was accounted for as a combination of entities under common control at historical cost in a manner similar to the pooling of interest method.
	Concurrent with the closing of the Cinco Group acquisition, our revolving credit facility was amended to increase the maximum borrowing capacity to $2.0 billion from $1.0 billion. The borrowing base was also increased from $480.0 million to $920.0 million. On October 10, 2013, the borrowing base was automatically reduced by $75.0 million in conjunction with the issuance of additional Senior Notes. See Note 8 for additional information regarding our revolving credit facility and Senior Notes.
	Our Current Report on Form 8-K filed on October 1, 2013 included audited supplemental consolidated and combined balance sheets as of December 31, 2012 and 2011, and the related supplemental consolidated and combined statements of operations, equity, and cash flows for each of the years in the three-year period ended December 31, 2012 to retrospectively revise certain of our financial and other information to give effect to the Cinco Group acquisition. Such information was previously revised for the WHT acquisition as described in and filed with our Current Report on Form 8-K filed on June 19, 2013. This Quarterly Report on Form 10-Q has not been recast for the Cinco Group acquisition, which closed on October 1, 2013.
	March 2013 Acquisition. On March 28, 2013, we acquired all of the outstanding equity interests in WHT from operating subsidiaries of Memorial Resource for a purchase price of $200.0 million, which included $4.0 million of working capital and other customary adjustments. This acquisition was funded with borrowings under our revolving credit facility and the net proceeds from our March 25, 2013 public offering of common units (including our general partner’s proportionate capital contribution). The effective date for this transaction was January 1, 2013. Terms of the transaction were approved by our general partner’s board of directors and by its conflicts committee. The acquired properties consist of additional working interests in properties that we originally acquired in December 2011 in conjunction with our initial public offering. This acquisition was accounted for as a combination of entities under common control at historical cost in a manner similar to the pooling of interest method. The Partnership recorded the following net assets (in thousands):
	Cash and cash equivalents	$	1,354
	Accounts receivable		3,866
	Short-term derivative instruments, net		1,206
	Prepaid expenses and other current assets		98
	Oil and natural gas properties, net		192,280
	Long-term derivative instruments, net		3,528
	Accrued liabilities		(3,494)
	Asset retirement obligations		(2,753)
	Credit facilities		(89,300)
	Other long-term liabilities		(111)
	Net assets	$	106,674
	2012 Acquisitions. We acquired oil and gas properties from Memorial Resource in April and May 2012. In December 2012, we acquired our offshore Southern California properties and the associated onshore tankage and metering facility from an affiliate of Memorial Resource.
	Related Party Agreements
	We and certain of our affiliates have entered into various documents and agreements. These agreements have been negotiated among affiliated parties and, consequently, are not the result of arm’s-length negotiations.
	Omnibus Agreement
	Memorial Resource continues to provide management, administrative and operating services for us and our general partner pursuant to our omnibus agreement. The following table summarizes the amount of general and administrative expenses recognized under the omnibus agreement that are reflected in the accompanying statements of operations for the periods presented (in thousands):
		For the Three Months				For the Nine Months
		Ended September 30,				Ended September 30,
		2013		2012		2013		2012
		$	2,988	$	526	$	6,239	$	1,185
	Tax Sharing Agreement
	The tax sharing agreement pursuant to which we pay Memorial Resource (or its applicable affiliate(s)) our share of state and local income and other taxes for which our results are included in a combined or consolidated tax return filed by Memorial Resource or its applicable affiliate(s) also remains in effect.
	Beta Management Agreement
	The Partnership acquired REO, which owns certain operating interests in producing and non-producing oil and gas properties offshore Southern California, in December 2012. We refer to this transaction as the “Beta acquisition” and the acquired properties as the “Beta properties.” In connection with the Beta acquisition, Memorial Resource entered into a management agreement with its wholly-owned subsidiary, Beta Operating Company, LLC, pursuant to which Memorial Resource agreed to provide management and administrative oversight with respect to the services provided by such subsidiary under certain operating agreements with our subsidiary, Rise Energy Beta, LLC, related to the Beta properties in exchange for an annual management fee. Pursuant to such management agreement and in connection with such operating agreements, Memorial Resource will receive approximately $0.4 million from Rise Energy Beta, LLC annually.
	An affiliate of REO collected a management fee for providing administrative services to REO prior to the Beta acquisition. These administrative services included accounting, business development, finance, legal, information technology, insurance, government regulations, communications, regulatory, environmental and human resources services. The following table summarizes the amount of management fees REO incurred and paid, which are included in general and administrative expenses in the accompanying statements of operations for the periods presented (in thousands):
	For the Three Months	For the Nine Months
	Ended September 30,	Ended September  30,
	2012	2012
	$                                     345	$                            1,500
	WHT Management Agreement
	Memorial Resource controls WildHorse Resources, LLC (“WildHorse”) and Tanos Energy, LLC (“Tanos”), which collectively owned the outstanding equity interests in WHT prior to March 28, 2013. Under the terms of a management agreement dated April 8, 2011, WildHorse provided executive, financial, accounting and land services to WHT. WildHorse also managed day-to-day field operations and drilling activities. Geological, executive and other services were provided by Tanos. To compensate for these services, WHT paid WildHorse and Tanos management fees totaling approximately $0.2 million per month. In connection with the WHT acquisition, the management agreement was terminated as of March 28, 2013.
	As the designated operator, WildHorse received both operated and non-operated revenues on behalf of WHT and billed and received joint interest billings. WildHorse also paid for lease operating expenses, drilling cost and general and administrative costs on behalf of WHT. Receivable and payable balances were settled monthly between WHT and WildHorse.
	Memorial Resource Credit Facility
	As of November 1, 2013, Memorial Resource has a senior secured revolving credit facility, which is guaranteed by our general partner. Memorial Resource has pledged 7,061,294 of our common units, 5,360,912 of our subordinated units, and its ownership in our general partner as well as its oil and gas properties and certain other assets of Memorial Resource as security under the credit facility.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Note 13. Commitments and Contingencies
	Litigation & Environmental
	As part of our normal business activities, we may be named as defendants in litigation and legal proceedings, including those arising from regulatory and environmental matters. Although we are insured against various risks to the extent we believe it is prudent, there is no assurance that the nature and amount of such insurance will be adequate, in every case, to indemnify us against liabilities arising from future legal proceedings. We are not aware of any litigation, pending or threatened, that we believe is reasonably likely to have a significant adverse effect on our financial position, results of operations or cash flows.
	At September 30, 2013 and December 31, 2012, we had $0.5 million and $1.1 million of environmental reserves recorded on our balance sheets, respectively.
	Supplemental Bond for Decommissioning Liabilities Trust Agreement
	The following is a summary of the gross held-to-maturity investments held in the trust account less the outside working interest owners share as of September 30, 2013 (in thousands):
	Investment	Amortized		Unrealized		Fair Market
		Cost		Gain (Loss)		Value
	U.S. Bank Money Market Cash Equivalent	$	103,285	$	--	$	103,285
	U.S. Government Treasury Note, maturity of March 31, 2014, and 1.75% coupon		23,073		194		23,267
	Less: Outside working interest owners share		(60,968)		(93)		(61,061)
		$	65,390	$	101	$	65,491
	The trust account must maintain minimum balances attributable to REO’s net working interest as follows (in thousands):
	June 30, 2014	$	68,310
	June 30, 2015	$	72,450
	June 30, 2016	$	76,590
	December 31, 2016	$	78,660
	As of September 30, 2013, the maximum remaining obligation net to REO’s interest was approximately $13.2 million.

Subsequent_Events

Subsequent Events	9 Months Ended
	Sep. 30, 2013
Subsequent Events [Abstract]	'
Subsequent Events	'
	Note 14. Subsequent Events
	Common Control Acquisition
	The Cinco Group acquisition closed on October 1, 2013. See Note 12 for additional information regarding this acquisition. Additionally, our revolving credit facility was amended concurrent with the closing of the Cinco Group acquisition. See Note 8 for additional information regarding the amendment to our revolving credit facility.
	October 2013 Public Equity Offering
	On October 8, 2013, we issued 16,675,000 common units representing limited partner interests in the Partnership (including 2,175,000 common units purchased pursuant to the full exercise of the underwriters’ option to purchase additional common units) to the public at an offering price of $19.90 per unit. The net proceeds, including our general partner’s proportional capital contributions and after deducting underwriting discounts and commissions but before estimated expenses, was approximately $319.2 million. The net proceeds were used to repay a portion of outstanding borrowings under our revolving credit facility.
	October 2013 Senior Notes Offering
	On October 10, 2013, the Issuers issued an additional $300.0 million aggregate principal amount of the Senior Notes at 97.0% of par. See Note 8 for more information regarding our Senior Notes.

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
General	'
	General
	Memorial Production Partners LP (the “Partnership”) is a publicly traded Delaware limited partnership, the common units of which are listed on the NASDAQ Global Market (“NASDAQ”) under the symbol “MEMP.” Unless the context requires otherwise, references to “we,” “us,” “our,” or “the Partnership” are intended to mean the business and operations of Memorial Production Partners LP and its consolidated subsidiaries.
	The Partnership was formed in April 2011 by Memorial Resource Development LLC to own, acquire and exploit oil and natural gas properties in North America. Unless the context requires otherwise, references to “Memorial Resource” refer collectively to Memorial Resource Development LLC and its subsidiaries other than the Partnership. The Partnership is owned 99.9% by its limited partners and 0.1% by its general partner, Memorial Production Partners GP LLC, which is a wholly-owned subsidiary of Memorial Resource. Our general partner is responsible for managing all of the Partnership’s operations and activities.
	We operate in one reportable segment engaged in the acquisition, exploitation, development and production of oil and natural gas properties. Our management evaluates performance based on one reportable business segment as there are not different economic environments within the operation of our oil and natural gas properties. Our business activities are conducted through Memorial Production Operating LLC (“OLLC”), our wholly-owned subsidiary, and its wholly-owned subsidiaries. Our assets consist primarily of producing oil and natural gas properties and are principally located in Texas, Louisiana and offshore Southern California. Most of our oil and natural gas properties are located in large, mature oil and natural gas reservoirs. The Partnership’s properties consist primarily of operated and non-operated working interests in producing and undeveloped leasehold acreage and working interests in identified producing wells (often referred to as wellbore assignments).
	Memorial Production Finance Corporation (“Finance Corp.”), our wholly-owned subsidiary, has no material assets or any liabilities other than as a co-issuer of our debt securities and as a guarantor of certain of our other indebtedness. Its activities will be limited to co-issuing our debt securities and engaging in other activities incidental thereto.
	Memorial Resource is a Delaware limited liability company owned and formed by Natural Gas Partners VIII, L.P., Natural Gas Partners IX, L.P. and NGP IX Offshore Holdings, L.P. (collectively, the “Funds”) to own, acquire, exploit and develop oil and natural gas properties and to own our general partner. Memorial Resource provides management, administrative, and operations personnel to us and our general partner under an omnibus agreement (see Note 12). The Funds are private equity funds managed by Natural Gas Partners (“NGP”). The Funds collectively directly own, through non-voting membership interests in our general partner, 50% of the economic interest in our incentive distribution rights (“IDRs”). The remaining economic interest in our IDRs is owned by our general partner.
	References to “the previous owners” for accounting and financial reporting purposes refer collectively to: (i) certain oil and natural gas properties the Partnership acquired from Memorial Resource in April and May 2012 for periods after common control commenced through their respective acquisition dates, (ii) Rise Energy Operating, LLC and its wholly-owned subsidiaries (except for Rise Energy Operating, Inc.) (“REO”) from February 3, 2009 (inception) through the date of acquisition; and (iii) certain oil and natural gas properties and related assets in East Texas and North Louisiana that the Partnership acquired in March 2013 (the “WHT Properties”) owned by WHT Energy Partners LLC (“WHT”) from February 2, 2011 (inception) through the date of acquisition. Each of these acquisitions was accounted for as a transaction between entities under common control, similar to a pooling of interests, whereby the net assets acquired were recorded at historical cost and certain financial and other information has been retrospectively revised to give effect to such acquisitions as if the Partnership owned the assets for periods after common control commenced through their respective acquisition dates. The WHT Properties represent additional working interests in properties that we originally acquired in December 2011 in conjunction with our initial public offering. See Note 12 for additional information regarding these common control transactions.
Basis of Presentation	'
	Basis of Presentation
	Our consolidated results of operations are presented together with the combined results of operations pertaining to the previous owners. The combined financial statements of the previous owners were derived from their historical accounting records and reflect their historical financial position, results of operations and cash flows.
	The ownership interest of the noncontrolling shareholder in the San Pedro Bay Pipeline Company (“SPBPC”), an indirect majority-owned subsidiary of the Partnership, is presented as a noncontrolling interest in the financial statements.
	Our results of operations for the three and nine months ended September 30, 2013 are not necessarily indicative of results expected for the full year. In our opinion, the accompanying unaudited condensed consolidated and combined financial statements include all adjustments of a normal recurring nature necessary for fair presentation. Although we believe the disclosures in these financial statements are adequate and make the information presented not misleading, certain information and footnote disclosures normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted pursuant to the rules and regulations of the United States Securities and Exchange Commission (“SEC”). These unaudited condensed consolidated and combined financial statements and the notes thereto should be read in conjunction with the recast audited consolidated and combined financial statements and notes thereto included in our Current Report on Form 8-K filed on June 19, 2013 (our “Recast Form 8-K”). On October 1, 2013, we filed a Current Report on Form 8-K, which included audited supplemental financial statements that retrospectively revised certain of our financial and other information to give effect to the Cinco Group acquisition (see Note 12). This Quarterly Report on Form 10-Q has not been recast for the Cinco Group acquisition which closed on October 1, 2013.
	All material intercompany transactions and balances have been eliminated in preparation of our consolidated and combined financial statements.
Use of Estimates	'
	Use of Estimates
	The preparation of the accompanying unaudited condensed consolidated and combined financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated and combined financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
	Significant estimates include, but are not limited to, oil and natural gas reserves; depreciation, depletion, and amortization of proved oil and natural gas properties; future cash flows from oil and natural gas properties; impairment of long-lived assets; fair value of derivatives; fair value of equity compensation; fair values of assets acquired and liabilities assumed in business combinations and asset retirement obligations.
Current Liabilities	'
	Current Liabilities
	Current accrued liabilities consisted of the following at the dates indicated (in thousands):
		September 30,		December 31,
		2013		2012
	Accrued capital expenditures	$	20,600	$	4,742
	Accrued lease operating expense		4,966		3,944
	Accrued interest payable(1)		13,994		618
	Accrued ad valorem		3,073		341
	Other		909		2,803
		$	43,542	$	12,448
	(1)    Increase in accrued interest payable primarily due to issuances of Senior Notes (see Note 8).
New Accounting Pronouncements	'
	New Accounting Pronouncements
	Offsetting Disclosure Requirements. In December 2011, the FASB issued an accounting standard update intended to enhance current disclosure requirements on offsetting financial assets and liabilities. In January 2013, the FASB issued an accounting standard update to clarify the scope of offsetting disclosure requirements. The disclosure requirements require the disclosure of both gross and net information about derivatives, repurchase agreements and reverse purchase agreements, and securities borrowing and securities lending transactions eligible for offset on the balance sheet or subject to a master netting arrangement or similar agreement. Disclosure of collateral received and posted in connection with master netting agreements or similar arrangements is also required. We adopted this guidance on January 1, 2013 and applied the disclosure requirements retrospectively. The enhanced offsetting disclosure requirements did not have a significant impact on our financial statements.
	Other accounting standards that have been issued by the FASB or other standards-setting bodies are not expected to have a material impact on the Partnership’s financial position, results of operations and cash flows.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Summary of Current Accrued Liabilities	'
	Current accrued liabilities consisted of the following at the dates indicated (in thousands):
		September 30,		December 31,
		2013		2012
	Accrued capital expenditures	$	20,600	$	4,742
	Accrued lease operating expense		4,966		3,944
	Accrued interest payable(1)		13,994		618
	Accrued ad valorem		3,073		341
	Other		909		2,803
		$	43,542	$	12,448
	(1)    Increase in accrued interest payable primarily due to issuances of Senior Notes (see Note 8).

Acquisitions_and_Divestitures_

Acquisitions and Divestitures (Tables)	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Summary of Fair value of Assets Acquired and Liabilities Assumed	'
	The following table summarizes our preliminary purchase price allocations as of each acquisition date (in thousands):
		East Texas		Rockies
		Acquisition		Acquisition
	Oil and gas properties	$	9,974	$	20,744
	Asset retirement obligations		(78)		(1,163)
	Accrued liabilities		--		(118)
	Total identifiable net assets	$	9,896	$	19,463
Acquisition-Related Costs	'
	Acquisition-related costs. Acquisition-related costs for both related party and third party transactions are included in general and administrative expenses in the accompanying statements of operations for the periods indicated below (in thousands):
	For the Three Months			For the Nine Months
	Ended September 30,			Ended September 30,
	2013	2012		2013		2012
	$                    2,310	$	381	$	3,422	$	780
Supplemental Pro Forma Information	'
	The unaudited pro forma financial information does not purport to be indicative of results of operations that would have occurred had the transactions occurred on the basis assumed above, nor is such information indicative of expected future results of operations.
		For the Three Months		For the Nine Months
		Ended September 30,		Ended September 30,
		2012		2012
		(In thousands, except per unit amounts)
	Revenues	$	47,634	$	146,777
	Net income (loss)		(22,455)		33,140
	Basic and diluted earnings per unit		(1.06)		0.17

Fair_Value_Measurements_of_Fin1

Fair Value Measurements of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Assets and Liabilities Measured at Fair Value on Recurring Basis	'
	The following table presents the gross derivative assets and liabilities that are measured at fair value on a recurring basis at September 30, 2013 and December 31, 2012 for each of the fair value hierarchy levels:
		Fair Value Measurements at September 30, 2013 Using
		Quoted Prices in		Significant Other		Significant		Fair Value
		Active Market		Observable Inputs		Unobservable Inputs
		(Level 1)		(Level 2)		(Level 3)
		(In thousands)
	Assets:
	Commodity derivatives	$	--	$	87,487	$	--	$	87,487
	Liabilities:
	Commodity derivatives	$	--	$	48,450	$	--	$	48,450
	Interest rate derivatives		--		3,736		--		3,736
	Total liabilities	$	--	$	52,186	$	--	$	52,186
		Fair Value Measurements at December 31, 2012 Using
		Quoted Prices in		Significant Other		Significant		Fair Value
		Active Market		Observable Inputs		Unobservable Inputs
		(Level 1)		(Level 2)		(Level 3)
		(In thousands)
	Assets:
	Commodity derivatives	$	--	$	69,303	$	--	$	69,303
	Liabilities:
	Commodity derivatives	$	--	$	41,814	$	--	$	41,814
	Interest rate derivatives		--		5,087		--		5,087
	Total liabilities	$	--	$	46,901	$	--	$	46,901
	See Note 5 for additional information regarding our derivative instruments.

Risk_Management_and_Derivative1

Risk Management and Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]	'
Open Commodity Positions	'
	At September 30, 2013, we had the following open commodity positions:
			Remaining				2014				2015			2016				2017		2018		2019
			2013
	Natural Gas Derivative Contracts:
	Fixed price swap contracts:
	Average Monthly Volume (MMBtu)			1,345,172				1,860,458				1,785,278			1,842,442				1,690,067		1,660,000		1,514,583
	Weighted-average fixed price		$	4.32			$	4.34			$	4.3		$	4.47			$	4.33	$	4.58	$	4.87
	Collar contracts:
	Average Monthly Volume (MMBtu)			840,000				300,000				200,000			--				--		--		--
	Weighted-average floor price		$	4.82			$	5.08			$	5.25		$	--			$	--	$	--	$	--
	Weighted-average ceiling price		$	5.88			$	6.31			$	6.75		$	--			$	--	$	--	$	--
	Call spreads (1):
	Average Monthly Volume (MMBtu)			430,000				120,000				80,000			--				--		--		--
	Weighted-average sold strike price		$	4.59			$	5.08			$	5.25		$	--			$	--	$	--	$	--
	Weighted-average bought strike price		$	5.84			$	6.31			$	6.75		$	--			$	--	$	--	$	--
	Basis swaps:
	Average Monthly Volume (MMBtu)			1,620,932				2,224,583				--			--				--		--		--
	Spread		$	-0.1			$	-0.09			$	--		$	--			$	--	$	--	$	--
	Crude Oil Derivative Contracts:
	Fixed price swap contracts:
	Average Monthly Volume (Bbls)			73,632				78,477				96,281			116,013				105,500		100,000		--
	Weighted-average fixed price		$	102.53			$	97.4			$	93.72		$	86.97			$	85.84	$	85.34	$	--
	Collar contracts:
	Average Monthly Volume (Bbls)			10,600				8,000				--			--				--		--		--
	Weighted-average floor price		$	88.87			$	90			$	--		$	--			$	--	$	--	$	--
	Weighted-average ceiling price		$	118.59			$	117.72			$	--		$	--			$	--	$	--	$	--
	Basis swaps:
	Average Monthly Volume (Bbls)			40,000				49,958				47,500			--				--		--		--
	Spread		$	-10.2			$	-9.04			$	-9.6		$	--			$	--	$	--	$	--
	NGL Derivative Contracts:
	Fixed price swap contracts:
	Average Monthly Volume (Bbls)			94,871				84,150				85,300			--				--		--		--
	Weighted-average fixed price		$	39.49			$	39.76			$	35.12		$	--			$	--	$	--	$	--
	-1	These transactions were entered into for the purpose of eliminating the ceiling portion of certain collar arrangements, which effectively converted the applicable collars into swaps.
Interest Rate Swap Open Positions	'
	At September 30, 2013, we had the following interest rate swap open positions:
	Period Covered		Notional				Floating Rate		Fixed Rate				Fixed Rate Payer
			($ in thousands)
	April 2011 to April 2014 (1)		$	75,000			1 Month LIBOR			1.51	%		Partnership
	April 2013 to October 2013		$	75,000			1 Month LIBOR			1.51	%		Counterparty
	January 2013 to December 2016		$	100,000			1 Month LIBOR			1.305	%		Partnership
	April 2013 to October 2013		$	40,000			1 Month LIBOR			1.305	%		Counterparty
	January 2013 to December 2016		$	50,000			1 Month LIBOR			0.97	%		Partnership
	October 2013 to April 2014		$	40,000			1 Month LIBOR			1.37	%		Partnership
	April 2014 to October 2014		$	75,000			1 Month LIBOR			1.64	%		Partnership
	June 2013 to October 2013		$	110,000			1 Month LIBOR			1.153	%		Counterparty
	October 2014 to February 2015		$	110,000			1 Month LIBOR			1.4	%		Partnership
		(1)	These interest rate swaps were novated to the Partnership from the previous owners in connection with the March 2013 acquisition.
	In October 2013, we entered into offsetting interest rate swap derivative instruments to avoid being economically over-hedged. We will receive the fixed rate and will pay the floating rate as follows:
	Period Covered		Notional				Floating Rate		Fixed Rate				Fixed Rate Payer
			($ in thousands)
	October 2013 to April 2014		$	150,000			1 Month LIBOR			1.193	%		Counterparty
	October 2013 to April 2014		$	75,000			1 Month LIBOR			1.51	%		Counterparty
	February 2015 to August 2015		$	225,000			1 Month LIBOR			1.715	%		Partnership
Gross Fair Value of Derivative Instruments by Appropriate Balance Sheet	'
	The following table summarizes both: (i) the gross fair value of derivative instruments by the appropriate balance sheet classification even when the derivative instruments are subject to netting arrangements and qualify for net presentation in the balance sheet and (ii) the net recorded fair value as reflected on the balance sheet at September 30, 2013 and December 31, 2012. There was no cash collateral received or pledged associated with our derivative instruments since each of the counterparties to our derivative contracts is a lender under our credit agreement.
							Asset Derivatives							Liability Derivatives
							September 30,				December 31,			September 30,				December 31,
	Type		Balance Sheet Location				2013				2012			2013				2012
							(In thousands)
	Natural gas contracts			Short-term derivative instruments			$	18,714			$	22,069		$	582			$	961
	Oil contracts			Short-term derivative instruments				3,469				6,453			6,102				4,483
	NGL contracts			Short-term derivative instruments				1,722				871			1,515				1,124
	Interest rate swaps			Short-term derivative instruments				--				--			2,500				2,369
	Gross fair value							23,905				29,393			10,699				8,937
	Netting arrangements			Short-term derivative instruments				(7,515)				(6,302)			(7,515)				(6,302)
	Net recorded fair value			Short-term derivative instruments			$	16,390			$	23,091		$	3,184			$	2,635
	Natural gas contracts			Long-term derivative instruments			$	30,067			$	17,435		$	6,055			$	9,352
	Oil contracts			Long-term derivative instruments				32,663				22,471			32,989				25,360
	NGL contracts			Long-term derivative instruments				852				4			1,207				534
	Interest rate swaps			Long-term derivative instruments				--				--			1,236				2,718
	Gross fair value							63,582				39,910			41,487				37,964
	Netting arrangements			Long-term derivative instruments				(35,692)				(28,386)			(35,692)				(28,386)
	Net recorded fair value			Long-term derivative instruments			$	27,890			$	11,524		$	5,795			$	9,578
Unrealized and Realized Gains and Losses Related to Derivative Instruments	'
	The following table details the gains and losses related to derivative instruments for the three and nine months ended September 30, 2013 and 2012 (in thousands):
					For the Three Months											For the Nine Months
					Ended September 30,											Ended September 30,
	Statements of				2013						2012					2013				2012
	Operations Location
	Commodity derivative contracts		(Gain) loss on commodity derivatives		$	(1,443)					$	28,427				$	(24,158)			$	(10,224)
	Interest rate derivatives		Interest expense			1,022						1,604					-423				4,631

Asset_Retirement_Obligations_T

Asset Retirement Obligations (Tables)	9 Months Ended
	Sep. 30, 2013
Asset Retirement Obligation Disclosure [Abstract]	'
Summary of Changes in Asset Retirement Obligations	'
	The following table presents the changes in the asset retirement obligations for the nine months ended September 30, 2013 (in thousands):
	Asset retirement obligations at beginning of period	$	78,286
	Liabilities added from acquisitions or drilling		1,278
	Liabilities removed upon plugging and abandoning		(18)
	Accretion expense		3,022
	Asset retirement obligations at end of period	$	82,568

Restricted_Investments_Tables

Restricted Investments (Tables)	9 Months Ended
	Sep. 30, 2013
Text Block [Abstract]	'
Restricted Investment Balance	'
	The components of the restricted investment balance consisted of the following at the dates indicated:
		September 30,		December 31,
		2013		2012
		(In thousands)
	BOEM platform abandonment (See Note 13)	$	65,390	$	61,389
	BOEM lease bonds		776		776
	SPBPC Collateral:
	Contractual pipeline and surface facilities abandonment		2,222		1,959
	California State Lands Commission pipeline right-of-way bond		3,000		3,000
	City of Long Beach pipeline facility permit		500		500
	Federal pipeline right-of-way bond		300		300
	Port of Long Beach pipeline license		100		100
	Restricted investments	$	72,288	$	68,024

Long_Term_Debt_Tables

Long Term Debt (Tables)	9 Months Ended
	Sep. 30, 2013
Consolidated and Combined Debt Obligations	'
	The following table presents our consolidated and combined debt obligations at the dates indicated:
			September 30,		December 31,
			2013		2012
			(In thousands)
	OLLC $1.0 billion multi-year revolving credit facility, variable-rate, due March 2018		$	95,000	$	371,000
	7.625% senior notes, fixed-rate, due May 1, 2021 (1)			400,000		--
	WHT $400.0 million revolving credit facility, variable-rate, terminated March 2013			--		89,300
	Unamortized discounts			(2,276)		--
	Total long-term debt		$	492,724	$	460,300
		-1	The estimated fair value of our fixed-rate debt was $386.0 million. The estimated fair value is based on quoted market prices and is classified as Level 1 within the fair value hierarchy.
Borrowing Base Credit Facility	'
	The borrowing base for each credit facility was the following at the dates indicated:
			September 30,		December 31,
			2013		2012
			(In thousands)
	OLLC $1.0 billion multi-year revolving credit facility, variable-rate, due March 2018		$	480,000	$	460,000
	WHT $400.0 million revolving credit facility, variable-rate, terminated March 2013			--		120,000
	Total borrowing base		$	480,000	$	580,000
Summary of Weighted-Average Interest Rates Paid on Consolidated and Combined Variable-Rate Debt Obligations	'
	The following table presents the weighted-average interest rates paid on our consolidated and combined variable-rate debt obligations for the periods presented:
			For the Three Months								For the Nine Months
			Ended September 30,								Ended September 30,
			2013				2012				2013		2012
	OLLC revolving credit facility			2.13%				2.79%				2.55%		2.79%
	WHT revolving credit facility			n/a				2.88%				2.29%		2.81%
	REO revolving credit facility			n/a				3.19%				n/a		3.31%
Summary of Unamortized Deferred Financing Costs Associated with Consolidated and Combined Debt Obligations	'
	Unamortized deferred financing costs associated with our consolidated and combined debt obligations were as follows at the dates indicated:
			September 30,		December 31,
			2013		2012
			(In thousands)
	OLLC $1.0 billion multi-year revolving credit facility, variable-rate, due March 2018 (1)		$	3,542	$	3,359
	Senior Notes (2)			8,871		--
	WHT $400.0 million revolving credit facility, variable-rate, terminated March 2013 (3)			--		1,419
		-1	Additional financing costs were incurred in connection with the borrowing base increase that became effective March 28, 2013. Unamortized deferred financing costs are amortized over the remaining life of our revolving credit facility. As disclosed above, the borrowing base was automatically reduced upon issuance of the Senior Notes. As a result, approximately $0.9 million of deferred financing costs were written-off during the nine months ended September 30, 2013 and are included in interest expense in the accompanying statements of operations.
		-2	Unamortized deferred financing costs are amortized using the straight line method which approximates the effective interest method.
		-3	The unamortized deferred financing costs were written-off at the time the debt was repaid and the facility was terminated on March 28, 2013.
Revolving Credit Facility [Member]	'
Borrowing Base Credit Facility	'
	The following table presents borrowings and repayments under our consolidated and combined revolving credit facilities for the periods presented (in thousands):
			OLLC Revolving		WHT Revolving				REO Revolving		Total
			Credit Facility		Credit Facility				Credit Facility
	For the Nine Months Ended September 30, 2013:
	Advances on revolving credit facility		$	298,000	$	1,000			$	--	$	299,000
	Payments on revolving credit facility			(574,000)		(90,300)				--		(664,300)
	For the Nine Months Ended September 30, 2012:
	Advances on revolving credit facility		$	186,000	$	1,000			$	7,000	$	194,000
	Payments on revolving credit facility			-13,000		-5,900				(12,000)		-30,900

Equity_Distributions_Tables

Equity & Distributions (Tables)	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
Summary of Changes in Number of Outstanding Units	'
	The following table summarizes changes in the number of outstanding units since December 31, 2012:
			Common			Subordinated				General
										Partner
	Balance December 31, 2012			28,921,903			5,360,912				34,317
	Common units issued			9,775,000			--				--
	Restricted common units issued			515,947			--				--
	Restricted common units forfeited			(11,734)			--				--
	Restricted common units repurchased (1)			(7,056)			--				--
	General partner units issued			--			--				10,284
	Balance September 30, 2013			39,194,060			5,360,912				44,601
		-1	Restricted common units are generally net-settled by unitholders to cover the required withholding tax upon vesting. Unitholders surrendered units with value equivalent to the employees’ minimum statutory obligation for the applicable income and other employment taxes. Total payments remitted for the employees’ tax obligations to the appropriate taxing authorities were $0.1 million. These net-settlements had the effect of unit repurchases by the Partnership as they reduced the number of units that would have otherwise been outstanding as a result of the vesting and did not represent an expense to the Partnership.
Summary of Quarterly Cash Distribution Rates	'
	The following table summarizes our declared quarterly cash distribution rates with respect to the quarter indicated (dollars in millions, except per unit amounts):
	Quarter		Declaration Date		Record Date	Payable Date		Amount				Aggregate		Memorial
								Per Unit (1)				Distribution (2)		Resource
														Distribution
	3rd Quarter 2013		October 22, 2013		November 1, 2013	November 12, 2013		$	0.55			$	33.8	$	6.9
	2nd Quarter 2013		18-Jul-13		1-Aug-13	12-Aug-13		$	0.5125			$	22.9	$	6.4
	1st Quarter 2013		18-Apr-13		1-May-13	13-May-13		$	0.5125			$	22.6	$	6.4
	4th Quarter 2012		15-Jan-13		1-Feb-13	13-Feb-13		$	0.5075			$	17.4	$	6.3
	3rd Quarter 2012		19-Oct-12		1-Nov-12	12-Nov-12		$	0.495			$	11.1	$	6.2
	2nd Quarter 2012		19-Jul-12		1-Aug-12	13-Aug-12		$	0.48			$	10.7	$	6.0
	1st Quarter 2012		19-Apr-12		1-May-12	14-May-12		$	0.48			$	10.7	$	6.0
	4th Quarter 2011		26-Jan-12		6-Feb-12	13-Feb-12		$	0.0929			$	2	$	1.2
	(1)	The $0.0929 per unit pro-rated distribution paid on February 13, 2012 was based upon the minimum quarterly distribution of $0.4750 per unit adjusted to take into account the 18-day period of the fourth quarter of 2011 during which the Partnership was a public entity.
	(2)	The aggregate distribution for the third quarter of 2013 reflects the October 2013 public equity offering (see Note 14).

Earnings_per_Unit_Tables

Earnings per Unit (Tables)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Calculation of Earnings (Loss) Per Unit	'
	The following sets forth the calculation of earnings (loss) per unit, or EPU, for the periods indicated (in thousands, except per unit amounts):
		For the		For the		For the		For the
		Three Months		Three Months		Nine Months		Nine Months
		Ended		Ended		Ended		Ended
		September 30,		September 30,		September 30,		September 30,
		2013		2012		2013		2012
	Net income (loss) attributable to partners	$	(43,293)	$	(25,332)	$	(2,136)	$	(4,692)
	Less: General partner’s 0.1% interest in net income (loss)		(43)		(25)		(2)		(5)
	Less: IDRs		(40)		--		(40)		--
	Net income (loss) available to limited partners	$	(43,210)	$	(25,307)	$	(2,094)	$	(4,687)
	Weighted average limited partner units outstanding:
	Common units		39,195		16,941		35,954		16,880
	Subordinated units		5,361		5,361		5,361		5,361
	Total		44,556		22,302		41,315		22,241
	Basic and diluted EPU	$	(0.97)	$	(1.13)	$	(0.05)	$	(0.21)

Equitybased_Awards_Tables

Equity-based Awards (Tables)	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Summary of Information Regarding Restricted Common Unit Awards	'
	The following table summarizes information regarding restricted common unit awards granted under the Memorial Production Partners GP LLC Long-Term Incentive Plan (“LTIP”) for the periods presented:
			Number of Units		Weighted-
					Average Grant
					Date Fair Value
					per Unit (1)
	Restricted common units outstanding at December 31, 2012			285,609	$	18.08
	Granted (2)			515,947	$	18.81
	Forfeited			(11,734)	$	17.24
	Vested			(91,154)	$	18.31
	Restricted common units outstanding at September 30, 2013			698,668	$	18.6
		-1	Determined by dividing the aggregate grant date fair value of awards by the number of awards issued.
		-2	The aggregate grant date fair value of restricted common unit awards issued in 2013 was $9.7 million based on grant date market prices ranging from of $18.33 to $19.88 per unit.
Summary of Amount of Compensation Expense Recognized	'
	The following table summarizes the amount of recognized compensation expense associated with these awards that are reflected in the accompanying statements of operations for the periods presented (in thousands):
			For the Three Months						For the Nine Months
			Ended September 30,						Ended September 30,
			2013				2012		2013		2012
			$	1,237			$	418	$	2,322	$	993

Related_Party_Transactions_Tab

Related Party Transactions (Tables)	9 Months Ended
	Sep. 30, 2013
Related Party Transactions Reflected in Accompanying Statements of Operations	'
	The following table summarizes the amount of related party transactions reflected in the accompanying statements of operations for the periods presented (in thousands):
		For the Three Months				For the Nine Months
		Ended September 30,				Ended September 30,
		2013		2012		2013		2012
		$	3,151	$	1,614	$	7,880	$	4,747
Schedule of Net Assets Recorded by the Partnership (Common Control Acquisitions)	'
	The Partnership recorded the following net assets (in thousands):
	Cash and cash equivalents	$	1,354
	Accounts receivable		3,866
	Short-term derivative instruments, net		1,206
	Prepaid expenses and other current assets		98
	Oil and natural gas properties, net		192,280
	Long-term derivative instruments, net		3,528
	Accrued liabilities		(3,494)
	Asset retirement obligations		(2,753)
	Credit facilities		(89,300)
	Other long-term liabilities		(111)
	Net assets	$	106,674
REO [Member]	'
Related Party Transactions Reflected in Accompanying Statements of Operations	'
	The following table summarizes the amount of management fees REO incurred and paid, which are included in general and administrative expenses in the accompanying statements of operations for the periods presented (in thousands):
	For the Three Months	For the Nine Months
	Ended September 30,	Ended September  30,
	2012	2012
	$                                     345	$                            1,500
Omnibus Plans [Member]	'
Related Party Transactions Reflected in Accompanying Statements of Operations	'
	The following table summarizes the amount of general and administrative expenses recognized under the omnibus agreement that are reflected in the accompanying statements of operations for the periods presented (in thousands):
		For the Three Months				For the Nine Months
		Ended September 30,				Ended September 30,
		2013		2012		2013		2012
		$	2,988	$	526	$	6,239	$	1,185

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Gross Held-to-Maturity Investments	'
	The following is a summary of the gross held-to-maturity investments held in the trust account less the outside working interest owners share as of September 30, 2013 (in thousands):
	Investment	Amortized		Unrealized		Fair Market
		Cost		Gain (Loss)		Value
	U.S. Bank Money Market Cash Equivalent	$	103,285	$	--	$	103,285
	U.S. Government Treasury Note, maturity of March 31, 2014, and 1.75% coupon		23,073		194		23,267
	Less: Outside working interest owners share		(60,968)		(93)		(61,061)
		$	65,390	$	101	$	65,491
Minimum Balances Attributable to Net Working Interest	'
	The trust account must maintain minimum balances attributable to REO’s net working interest as follows (in thousands):
	June 30, 2014	$	68,310
	June 30, 2015	$	72,450
	June 30, 2016	$	76,590
	December 31, 2016	$	78,660

Organization_and_Basis_of_Pres2

Organization and Basis of Presentation - Additional Information (Detail)	Sep. 30, 2013
Limited Partners Common [Member]	'
Organization And Basis Of Presentation Textual [Abstract]	'
Partnership Ownership Percentage	99.90%
General Partner [Member]	'
Organization And Basis Of Presentation Textual [Abstract]	'
Partnership Ownership Percentage	0.10%
General Partner [Member] | The Funds [Member]	'
Organization And Basis Of Presentation Textual [Abstract]	'
Percentage of economic interest in incentive distribution rights	50.00%

Summary_of_Significant_Account2

Summary of Significant Accounting Policies - Summary of Current Accrued Liabilities (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Accrued Liabilities Current [Abstract]	'	'
Accrued capital expenditures	$20,600	$4,742
Accrued lease operating expense	4,966	3,944
Accrued interest payable	13,994	618
Accrued ad valorem	3,073	341
Other	909	2,803
Accrued Liabilities, Total	$43,542	$12,448

Acquisitions_and_Divestitures_1

Acquisitions and Divestitures - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended	9 Months Ended	1 Months Ended
In Millions, unless otherwise specified	1-May-12	Sep. 30, 2013	Sep. 30, 2013	Aug. 30, 2013	Sep. 06, 2013
		East Texas And Rockies [Member]	East Texas And Rockies [Member]	Rockies [Member]	East Texas [Member]
Business Acquisition And Divestiture [Line Items]	'	'	'	'	'
Purchase price	$36.50	$29	$29	'	'
Business acquisition closing date	'	'	'	30-Aug-13	6-Sep-13

Acquisitions_and_Divestitures_2

Acquisitions and Divestitures - Summary of Fair value of Assets Acquired and Liabilities Assumed (Detail) (USD $)	Sep. 06, 2013	Aug. 30, 2013
In Thousands, unless otherwise specified	East Texas [Member]	Rockies [Member]
Business Acquisition And Divestiture [Line Items]	'	'
Oil and gas properties	$9,974	$20,744
Asset retirement obligations	-78	-1,163
Accrued liabilities	'	-118
Total identifiable net assets	$9,896	$19,463

Acquisitions_and_Divestitures_3

Acquisitions and Divestitures - Acquisition-Related Costs (Detail) (General and Administrative Expenses [Member], USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
General and Administrative Expenses [Member]	'	'	'	'
Acquisitions And Divestitures Textual [Abstract]	'	'	'	'
Acquisition-related costs	$2,310	$381	$3,422	$780

Acquisitions_and_Divestitures_4

Acquisitions and Divestitures - Supplemental Pro Forma Information (Detail) (USD $)	3 Months Ended	9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2012	Sep. 30, 2012
Business Acquisition Pro Forma Information [Abstract]	'	'
Revenues	$47,634	$146,777
Net income (loss)	($22,455)	$33,140
Basic and diluted earnings per unit	($1.06)	$0.17

Fair_Value_Measurements_of_Fin2

Fair Value Measurements of Financial Instruments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Fair Value [Member], USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Liabilities	$52,186	$46,901
Interest rate derivatives [Member]	'	'
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Liabilities	3,736	5,087
Quoted Prices in Active Market (Level 1) [Member]	'	'
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Liabilities	'	'
Quoted Prices in Active Market (Level 1) [Member] | Interest rate derivatives [Member]	'	'
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Liabilities	'	'
Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Liabilities	52,186	46,901
Significant Other Observable Inputs (Level 2) [Member] | Interest rate derivatives [Member]	'	'
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Liabilities	3,736	5,087
Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Liabilities	'	'
Significant Unobservable Inputs (Level 3) [Member] | Interest rate derivatives [Member]	'	'
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Liabilities	'	'
Commodity derivatives [Member]	'	'
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Assets	87,487	69,303
Liabilities	48,450	41,814
Commodity derivatives [Member] | Quoted Prices in Active Market (Level 1) [Member]	'	'
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Assets	'	'
Liabilities	'	'
Commodity derivatives [Member] | Significant Other Observable Inputs (Level 2) [Member]	'	'
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Assets	87,487	69,303
Liabilities	48,450	41,814
Commodity derivatives [Member] | Significant Unobservable Inputs (Level 3) [Member]	'	'
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]	'	'
Assets	'	'
Liabilities	'	'

Fair_Value_Measurements_of_Fin3

Fair Value Measurements of Financial Instruments - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'	'	'	'
Impairment charges	$50,291	$0	$50,291	$0	'
Carrying value of properties after impairment charges	889,626	'	889,626	'	862,368
Impaired East Texas Properties [Member]	'	'	'	'	'
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]	'	'	'	'	'
Carrying value of properties after impairment charges	$31,500	'	$31,500	'	'

Risk_Management_and_Derivative2

Risk Management and Derivative Instruments - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013
Concentration Risks, Types, No Concentration Percentage [Abstract]	'
Conditional rights of set-off under ISDA Master Agreement reduce the maximum amount of loss due to credit risk	$25.50
Maximum amount of loss due to credit risk	18.8
Single Counterparty [Member]	'
Concentration Risks, Types, No Concentration Percentage [Abstract]	'
Maximum amount of loss due to credit risk	$11.60

Risk_Management_and_Derivative3

Risk Management and Derivative Instruments - Open Commodity Positions (Detail)	9 Months Ended
	Sep. 30, 2013
	MMBTU
Remaining 2013 [Member] | Natural Gas Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	1,345,172
Weighted-average fixed price	4.32
Remaining 2013 [Member] | Natural Gas Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	840,000
Weighted-average floor price	4.82
Weighted-average ceiling price	5.88
Remaining 2013 [Member] | Natural Gas Derivative Contracts Call Spreads [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	430,000
Weighted-average sold strike price	4.59
Weighted-average bought strike price	5.84
Remaining 2013 [Member] | Natural Gas Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	1,620,932
Spread	-0.1
Remaining 2013 [Member] | Crude Oil Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	73,632
Weighted-average fixed price	102.53
Remaining 2013 [Member] | Crude Oil Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	10,600
Weighted-average floor price	88.87
Weighted-average ceiling price	118.59
Remaining 2013 [Member] | Crude Oil Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	40,000
Spread	-10.2
Remaining 2013 [Member] | NGL Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	94,871
Weighted-average fixed price	39.49
2014 [Member] | Natural Gas Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	1,860,458
Weighted-average fixed price	4.34
2014 [Member] | Natural Gas Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	300,000
Weighted-average floor price	5.08
Weighted-average ceiling price	6.31
2014 [Member] | Natural Gas Derivative Contracts Call Spreads [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	120,000
Weighted-average sold strike price	5.08
Weighted-average bought strike price	6.31
2014 [Member] | Natural Gas Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	2,224,583
Spread	-0.09
2014 [Member] | Crude Oil Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	78,477
Weighted-average fixed price	97.4
2014 [Member] | Crude Oil Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	8,000
Weighted-average floor price	90
Weighted-average ceiling price	117.72
2014 [Member] | Crude Oil Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	49,958
Spread	-9.04
2014 [Member] | NGL Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	84,150
Weighted-average fixed price	39.76
2015 [Member] | Natural Gas Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	1,785,278
Weighted-average fixed price	4.3
2015 [Member] | Natural Gas Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	200,000
Weighted-average floor price	5.25
Weighted-average ceiling price	6.75
2015 [Member] | Natural Gas Derivative Contracts Call Spreads [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	80,000
Weighted-average sold strike price	5.25
Weighted-average bought strike price	6.75
2015 [Member] | Natural Gas Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Spread	'
2015 [Member] | Crude Oil Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	96,281
Weighted-average fixed price	93.72
2015 [Member] | Crude Oil Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Weighted-average floor price	'
Weighted-average ceiling price	'
2015 [Member] | Crude Oil Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	47,500
Spread	-9.6
2015 [Member] | NGL Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	85,300
Weighted-average fixed price	35.12
2016 [Member] | Natural Gas Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	1,842,442
Weighted-average fixed price	4.47
2016 [Member] | Natural Gas Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Weighted-average floor price	'
Weighted-average ceiling price	'
2016 [Member] | Natural Gas Derivative Contracts Call Spreads [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Weighted-average sold strike price	'
Weighted-average bought strike price	'
2016 [Member] | Natural Gas Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Spread	'
2016 [Member] | Crude Oil Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	116,013
Weighted-average fixed price	86.97
2016 [Member] | Crude Oil Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Weighted-average floor price	'
Weighted-average ceiling price	'
2016 [Member] | Crude Oil Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Spread	'
2016 [Member] | NGL Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Weighted-average fixed price	'
2017 [Member] | Natural Gas Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	1,690,067
Weighted-average fixed price	4.33
2017 [Member] | Natural Gas Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Weighted-average floor price	'
Weighted-average ceiling price	'
2017 [Member] | Natural Gas Derivative Contracts Call Spreads [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Weighted-average sold strike price	'
Weighted-average bought strike price	'
2017 [Member] | Natural Gas Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Spread	'
2017 [Member] | Crude Oil Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	105,500
Weighted-average fixed price	85.84
2017 [Member] | Crude Oil Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Weighted-average floor price	'
Weighted-average ceiling price	'
2017 [Member] | Crude Oil Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Spread	'
2017 [Member] | NGL Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Weighted-average fixed price	'
2018 [Member] | Natural Gas Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	1,660,000
Weighted-average fixed price	4.58
2018 [Member] | Natural Gas Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Weighted-average floor price	'
Weighted-average ceiling price	'
2018 [Member] | Natural Gas Derivative Contracts Call Spreads [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Weighted-average sold strike price	'
Weighted-average bought strike price	'
2018 [Member] | Natural Gas Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Spread	'
2018 [Member] | Crude Oil Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	100,000
Weighted-average fixed price	85.34
2018 [Member] | Crude Oil Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Weighted-average floor price	'
Weighted-average ceiling price	'
2018 [Member] | Crude Oil Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Spread	'
2018 [Member] | NGL Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Weighted-average fixed price	'
2019 [Member] | Natural Gas Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	1,514,583
Weighted-average fixed price	4.87
2019 [Member] | Natural Gas Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Weighted-average floor price	'
Weighted-average ceiling price	'
2019 [Member] | Natural Gas Derivative Contracts Call Spreads [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Weighted-average sold strike price	'
Weighted-average bought strike price	'
2019 [Member] | Natural Gas Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (MMBtu)	'
Spread	'
2019 [Member] | Crude Oil Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Weighted-average fixed price	'
2019 [Member] | Crude Oil Derivative Contracts Collar Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Weighted-average floor price	'
Weighted-average ceiling price	'
2019 [Member] | Crude Oil Derivative Contracts Basis Swaps [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Spread	'
2019 [Member] | NGL Derivative Contracts Fixed Price Swap Contracts [Member]	'
Combination Of Commodity Derivatives To Manage Exposure To Commodity Price Volatility [Abstract]	'
Average Monthly Volume (Bbls)	'
Weighted-average fixed price	'

Risk_Management_and_Derivative4

Risk Management and Derivative Instruments - Fixed-for Floating Interest Rate Swap Open Positions (Detail) (Interest rate derivatives [Member], USD $)

9 Months Ended

1 Months Ended

9 Months Ended

1 Months Ended

9 Months Ended

1 Months Ended

9 Months Ended

In Thousands, unless otherwise specified

Sep. 30, 2013

Oct. 31, 2013

Sep. 30, 2013

Oct. 31, 2013

Sep. 30, 2013

Oct. 31, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Range One [Member]

Range One [Member]

Range Two [Member]

Range Two [Member]

Range Three [Member]

Range Three [Member]

Range Four [Member]

Range Five [Member]

Range Six [Member]

Range Seven [Member]

Range Eight [Member]

Range Nine [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Derivative [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Effective dates of the swaps, inception date

30-Apr-11

31-Oct-13

30-Apr-13

31-Oct-13

31-Jan-13

28-Feb-15

30-Apr-13

31-Jan-13

31-Oct-13

30-Apr-14

30-Jun-13

31-Oct-14

Effective dates of the swaps, maturity date

30-Apr-14

30-Apr-14

31-Oct-13

30-Apr-14

31-Dec-16

31-Aug-15

31-Oct-13

31-Dec-16

30-Apr-14

31-Oct-14

31-Oct-13

28-Feb-15

Notional

$75,000

$150,000

$75,000

$75,000

$100,000

$225,000

$40,000

$50,000

$40,000

$75,000

$110,000

$110,000

Floating Rate

'1 Month LIBOR

'1 Month LIBOR

'1 Month LIBOR

'1 Month LIBOR

'1 Month LIBOR

'1 Month LIBOR

'1 Month LIBOR

'1 Month LIBOR

'1 Month LIBOR

'1 Month LIBOR

'1 Month LIBOR

'1 Month LIBOR

Fixed Rate

1.51%

1.19%

1.51%

1.51%

1.31%

1.72%

1.31%

0.97%

1.37%

1.64%

1.15%

1.40%

Risk_Management_and_Derivative5

Risk Management and Derivative Instruments - Gross Fair Value of Derivative Instruments by Appropriate Balance Sheet (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Derivative Instruments and Hedges, Assets [Abstract]	'	'
Asset Derivatives, Net recorded fair value	$16,390	$23,091
Asset Derivatives, Net recorded fair value	27,890	11,524
Liability Derivatives, Net recorded fair value	3,184	2,635
Liability Derivatives, Net recorded fair value	5,795	9,578
Short-Term Derivative Instruments [Member]	'	'
Derivative Instruments and Hedges, Assets [Abstract]	'	'
Asset Derivatives, Gross fair value	23,905	29,393
Asset Derivatives, Netting arrangements	-7,515	-6,302
Asset Derivatives, Net recorded fair value	16,390	23,091
Liability Derivatives, Gross fair value	10,699	8,937
Liability Derivatives, Netting arrangements	-7,515	-6,302
Liability Derivatives, Net recorded fair value	3,184	2,635
Short-Term Derivative Instruments [Member] | Natural Gas Contracts [Member]	'	'
Derivative Instruments and Hedges, Assets [Abstract]	'	'
Asset Derivatives, Gross fair value	18,714	22,069
Liability Derivatives, Gross fair value	582	961
Short-Term Derivative Instruments [Member] | Oil Contracts [Member]	'	'
Derivative Instruments and Hedges, Assets [Abstract]	'	'
Asset Derivatives, Gross fair value	3,469	6,453
Liability Derivatives, Gross fair value	6,102	4,483
Short-Term Derivative Instruments [Member] | NGL Contracts [Member]	'	'
Derivative Instruments and Hedges, Assets [Abstract]	'	'
Asset Derivatives, Gross fair value	1,722	871
Liability Derivatives, Gross fair value	1,515	1,124
Short-Term Derivative Instruments [Member] | Interest rate derivatives [Member]	'	'
Derivative Instruments and Hedges, Assets [Abstract]	'	'
Asset Derivatives, Gross fair value	'	'
Liability Derivatives, Gross fair value	2,500	2,369
Long-Term Derivative Instruments [Member]	'	'
Derivative Instruments and Hedges, Assets [Abstract]	'	'
Asset Derivatives, Gross fair value	63,582	39,910
Asset Derivatives, Netting arrangements	-35,692	-28,386
Asset Derivatives, Net recorded fair value	27,890	11,524
Liability Derivatives, Gross fair value	41,487	37,964
Liability Derivatives, Netting arrangements	-35,692	-28,386
Liability Derivatives, Net recorded fair value	5,795	9,578
Long-Term Derivative Instruments [Member] | Natural Gas Contracts [Member]	'	'
Derivative Instruments and Hedges, Assets [Abstract]	'	'
Asset Derivatives, Gross fair value	30,067	17,435
Liability Derivatives, Gross fair value	6,055	9,352
Long-Term Derivative Instruments [Member] | Oil Contracts [Member]	'	'
Derivative Instruments and Hedges, Assets [Abstract]	'	'
Asset Derivatives, Gross fair value	32,663	22,471
Liability Derivatives, Gross fair value	32,989	25,360
Long-Term Derivative Instruments [Member] | NGL Contracts [Member]	'	'
Derivative Instruments and Hedges, Assets [Abstract]	'	'
Asset Derivatives, Gross fair value	852	4
Liability Derivatives, Gross fair value	1,207	534
Long-Term Derivative Instruments [Member] | Interest rate derivatives [Member]	'	'
Derivative Instruments and Hedges, Assets [Abstract]	'	'
Asset Derivatives, Gross fair value	'	'
Liability Derivatives, Gross fair value	$1,236	$2,718

Risk_Management_and_Derivative6

Risk Management and Derivative Instruments - Unrealized and Realized Gains and Losses Related to Derivative Instruments (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Gain (Loss) on Derivative Instruments, Net, Pretax [Abstract]	'	'	'	'
(Gain) loss on commodity derivatives	($1,443)	$28,427	($24,158)	($10,224)
Interest expense, net	10,007	4,163	21,506	11,399
Commodity derivative contracts [Member]	'	'	'	'
Gain (Loss) on Derivative Instruments, Net, Pretax [Abstract]	'	'	'	'
(Gain) loss on commodity derivatives	-1,443	28,427	-24,158	-10,224
Interest rate derivatives [Member]	'	'	'	'
Gain (Loss) on Derivative Instruments, Net, Pretax [Abstract]	'	'	'	'
Interest expense, net	$1,022	$1,604	($423)	$4,631

Asset_Retirement_Obligations_S

Asset Retirement Obligations - Summary of Changes in Asset Retirement Obligations (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Asset Retirement Obligation Roll Forward Analysis [Roll Forward]	'	'	'	'
Asset retirement obligations at beginning of period	'	'	$78,286	'
Liabilities added from acquisitions or drilling	'	'	1,278	'
Liabilities removed upon plugging and abandoning	'	'	-18	'
Accretion expense	1,025	936	3,022	2,810
Asset retirement obligations at end of period	$82,568	'	$82,568	'

Restricted_Investments_Restric

Restricted Investments - Restricted Investment Balance (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Restricted Cash and Investments [Abstract]	'	'
Restricted investments	$72,288	$68,024
BOEM platform abandonment [Member]	'	'
Restricted Cash and Investments [Abstract]	'	'
Restricted investments	65,390	61,389
BOEM lease bonds [Member]	'	'
Restricted Cash and Investments [Abstract]	'	'
Restricted investments	776	776
SPBPC Collateral Contractual pipeline and surface facilities abandonment [Member]	'	'
Restricted Cash and Investments [Abstract]	'	'
Restricted investments	2,222	1,959
SPBPC Collateral California State Lands Commission pipeline right-of-way bond [Member]	'	'
Restricted Cash and Investments [Abstract]	'	'
Restricted investments	3,000	3,000
SPBPC Collateral City of Long Beach pipeline facility permit [Member]	'	'
Restricted Cash and Investments [Abstract]	'	'
Restricted investments	500	500
SPBPC Collateral Federal pipeline right-of-way bond [Member]	'	'
Restricted Cash and Investments [Abstract]	'	'
Restricted investments	300	300
SPBPC Collateral Port of Long Beach pipeline license [Member]	'	'
Restricted Cash and Investments [Abstract]	'	'
Restricted investments	$100	$100

Long_Term_Debt_Consolidated_an

Long Term Debt - Consolidated and Combined Debt Obligations (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Debt Obligations [Abstract]	'	'
Unamortized discounts	($2,276)	'
Total long-term debt	492,724	460,300
OLLC $1.0 billion multi-year revolving credit facility [Member]	'	'
Debt Obligations [Abstract]	'	'
Revolving credit facility	95,000	371,000
7.625% senior notes [Member]	'	'
Debt Obligations [Abstract]	'	'
7.625% senior notes, fixed-rate, due May 1, 2021	400,000	'
WHT $400.0 million revolving credit facility [Member]	'	'
Debt Obligations [Abstract]	'	'
Revolving credit facility	'	$89,300

Long_Term_Debt_Consolidated_an1

Long Term Debt - Consolidated and Combined Debt Obligations (Parenthetical) (Detail) (USD $)	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified		OLLC $1.0 billion multi-year revolving credit facility [Member]	7.625% senior notes [Member]	WHT $400.0 million revolving credit facility [Member]
Debt Obligations [Abstract]	'	'	'	'
Revolving credit facility	'	$1,000	'	$400
Senior notes	'	'	7.63%	'
Estimated fair value of fixed rate debt	$386	'	'	'

Long_Term_Debt_Additional_Info

Long Term Debt - Additional Information (Detail) (USD $)

Sep. 30, 2013

Mar. 28, 2013

Dec. 31, 2012

Sep. 30, 2013

23-May-13

Apr. 17, 2013

Sep. 30, 2013

Mar. 15, 2013

Sep. 30, 2013

Sep. 30, 2013

Mar. 28, 2013

Apr. 08, 2011

Sep. 30, 2013

Dec. 12, 2012

Oct. 26, 2011

Sep. 30, 2013

Oct. 10, 2013

Oct. 01, 2013

Oct. 10, 2013

Oct. 10, 2013

Oct. 01, 2013

7.625% Senior Notes [Member]

Private Placement [Member]

Private Placement [Member]

Universal Shelf Registration Statement [Member]

Universal Shelf Registration Statement [Member]

WHT [Member]

WHT [Member]

WHT [Member]

WHT [Member]

REO [Member]

REO [Member]

REO [Member]

OLLC [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

7.625% Senior Notes [Member]

7.625% Senior Notes [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

7.625% Senior Notes [Member]

Private Placement [Member]

OLLC [Member]

7.625% Senior Notes [Member]

Revolving Credit Facility [Member]

Credit Facilities [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Universal shelf registration statement on file with the SEC

'

'

'

'

'

'

'

$750,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Universal shelf guarantor subsidiaries ownership percentage

'

'

'

'

'

'

100.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Borrowing base

480,000,000

580,000,000

580,000,000

'

'

'

'

'

'

'

'

'

'

'

'

480,000,000

'

'

'

'

920,000,000

Borrowing base reduced amount

'

100,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

75,000,000

'

'

'

'

Borrowing base increased amount

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

440,000,000

'

'

'

Revolving credit facility

'

'

'

'

'

'

'

'

'

'

'

400,000,000

'

'

150,000,000

1,000,000,000

'

2,000,000,000

'

'

2,000,000,000

Maturity date of variable rate revolving credit facility

'

'

'

'

'

'

'

'

'

'April 8, 2016

'

'

'

'

'

'

'

'

'

'

'

Debt balance outstanding under the revolving credit facility at termination

'

'

'

'

'

'

'

'

'

'

89,300,000

'

'

28,500,000

'

'

'

'

'

'

'

Termination period of revolving credit facility

'

'

'

'

'

'

'

'

28-Mar-13

'

'

'

12-Dec-12

'

'

'

'

'

'

'

'

7.625% senior unsecured notes maturity period

'

'

'

1-May-21

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Face amount of 7.625% Senior Notes due 2021 at time of issuance

'

'

'

'

$100,000,000

$300,000,000

'

'

'

'

'

'

'

'

'

'

'

'

$300,000,000

$300,000,000

'

Senior notes issued at a discount or premium to par

'

'

'

'

102.00%

98.52%

'

'

'

'

'

'

'

'

'

'

'

'

97.00%

97.00%

'

Other events of default minimum note holder percentage to accelerate

'

'

'

25.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long_Term_Debt_Borrowing_Base_

Long Term Debt - Borrowing Base Credit Facility (Detail) (USD $)	Sep. 30, 2013	Mar. 28, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Credit Facilities [Line Items]	'	'	'
Borrowing base	$480,000	$580,000	$580,000
OLLC $1.0 billion multi-year revolving credit facility [Member]	'	'	'
Credit Facilities [Line Items]	'	'	'
Borrowing base	480,000	'	460,000
WHT $400.0 million revolving credit facility [Member]	'	'	'
Credit Facilities [Line Items]	'	'	'
Borrowing base	'	'	$120,000

Long_Term_Debt_Summary_of_Weig

Long Term Debt - Summary of Weighted-Average Interest Rates Paid on Consolidated and Combined Variable-Rate Debt Obligations (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
OLLC [Member]	'	'	'	'
Credit Facilities [Line Items]	'	'	'	'
Revolving credit facility, weighted-average interest rates	2.13%	2.79%	2.55%	2.79%
WHT [Member]	'	'	'	'
Credit Facilities [Line Items]	'	'	'	'
Revolving credit facility, weighted-average interest rates	'	2.88%	2.29%	2.81%
REO [Member]	'	'	'	'
Credit Facilities [Line Items]	'	'	'	'
Revolving credit facility, weighted-average interest rates	'	3.19%	'	3.31%

Long_Term_Debt_Summary_of_Unam

Long Term Debt - Summary of Unamortized Deferred Financing Costs Associated with Consolidated and Combined Debt Obligations (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
OLLC $1.0 billion multi-year revolving credit facility [Member]	'	'
Credit Facilities [Line Items]	'	'
Unamortized Debt Issuance Expense	$3,542	$3,359
WHT $400.0 million revolving credit facility [Member]	'	'
Credit Facilities [Line Items]	'	'
Unamortized Debt Issuance Expense	'	1,419
Senior Notes [Member]	'	'
Credit Facilities [Line Items]	'	'
Unamortized Debt Issuance Expense	$8,871	'

Long_Term_Debt_Summary_of_Unam1

Long Term Debt - Summary of Unamortized Deferred Financing Costs Associated with Consolidated and Combined Debt Obligations (Parenthetical) (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Deferred finance cost written off	$0.90

Long_Term_Debt_Summary_of_Borr

Long Term Debt - Summary of Borrowings and Repayments Under Consolidated and Combined Revolving Credit Facilities (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Credit Facilities [Line Items]	'	'
Advances on revolving credit facility	$299,000	$194,000
Payments on revolving credit facility	-664,300	-30,900
OLLC [Member]	'	'
Credit Facilities [Line Items]	'	'
Advances on revolving credit facility	298,000	186,000
Payments on revolving credit facility	-574,000	-13,000
WHT [Member]	'	'
Credit Facilities [Line Items]	'	'
Advances on revolving credit facility	1,000	1,000
Payments on revolving credit facility	-90,300	-5,900
REO [Member]	'	'
Credit Facilities [Line Items]	'	'
Advances on revolving credit facility	'	7,000
Payments on revolving credit facility	'	($12,000)

Equity_and_Distributions_Addit

Equity and Distributions - Additional Information (Detail) (USD $)	1 Months Ended	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 25, 2013	Sep. 30, 2013
Equity And Distributions Textual [Abstract]	'	'
Number of common units issued in public offering	9,775,000	'
Number of over-allotment common units issued by Partnership	1,275,000	'
Public offering price per common unit	$18.35	'
Net cash proceeds from public offering	$171,779	$171,779
Memorial Resource [Member]	'	'
Equity And Distributions Textual [Abstract]	'	'
Percentage of economic interest in incentive distribution rights	'	50.00%
Memorial Resource [Member] | Common Units [Member]	'	'
Equity And Distributions Textual [Abstract]	'	'
Partnership Ownership Percentage	'	18.00%
Memorial Resource [Member] | Subordinated Units [Member]	'	'
Equity And Distributions Textual [Abstract]	'	'
Partnership Ownership Percentage	'	100.00%
General Partner [Member]	'	'
Equity And Distributions Textual [Abstract]	'	'
Partnership Ownership Percentage	'	0.10%
General Partner [Member] | The Funds [Member]	'	'
Equity And Distributions Textual [Abstract]	'	'
Percentage of economic interest in incentive distribution rights	'	50.00%

Equity_and_Distributions_Summa

Equity and Distributions - Summary of Changes in Number of Outstanding Units (Detail)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012
		Common Units [Member]	Subordinated Units [Member]	Subordinated Units [Member]
Summary Of Changes In Number Of Outstanding Units [Abstract]	'	'	'	'
Balance December 31, 2012, General Partner	34,317	'	'	'
Balance December 31, 2012	28,921,903	28,921,903	5,360,912	5,360,912
Common units issued	'	9,775,000	'	'
Restricted common units issued	'	515,947	'	'
Restricted common units forfeited	'	-11,734	'	'
Restricted common units repurchased	'	-7,056	'	'
General partner units issued	10,284	'	'	'
Balance September 30, 2013	39,194,060	39,194,060	5,360,912	5,360,912
Balance September 30, 2013, General Partner	44,601	'	'	'

Equity_and_Distributions_Summa1

Equity and Distributions - Summary of Changes in Number of Outstanding Units (Parenthetical) (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013
Summary Of Changes In Number Of Outstanding Units [Abstract]	'
Withholding tax withheld and paid related to vesting of restricted common units	$0.10

Equity_and_Distributions_Summa2

Equity and Distributions - Summary of Quarterly Cash Distribution Rates (Detail) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Equity [Abstract]	'	'	'	'	'	'	'	'
Distribution made to member or limited partner, date of declaration	22-Oct-13	18-Jul-13	18-Apr-13	15-Jan-13	19-Oct-12	19-Jul-12	19-Apr-12	26-Jan-12
Distribution made to member or limited partner, date of record	1-Nov-13	1-Aug-13	1-May-13	1-Feb-13	1-Nov-12	1-Aug-12	1-May-12	6-Feb-12
Distribution made to member or limited partner, date of distribution	12-Nov-13	12-Aug-13	13-May-13	13-Feb-13	12-Nov-12	13-Aug-12	14-May-12	13-Feb-12
Distribution per unit	$0.55	$0.51	$0.51	$0.51	$0.50	$0.48	$0.48	$0.09
Aggregate Distribution	$33.80	$22.90	$22.60	$17.40	$11.10	$10.70	$10.70	$2
Distribution Received by Memorial Resource	$6.90	$6.40	$6.40	$6.30	$6.20	$6	$6	$1.20

Equity_and_Distributions_Summa3

Equity and Distributions - Summary of Quarterly Cash Distribution Rates (Parenthetical) (Detail) (USD $)	1 Months Ended	3 Months Ended
	Dec. 31, 2011	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Cash Distributions to Unitholders [Line Items]	'	'	'	'	'	'	'	'	'
Distribution per unit	'	$0.55	$0.51	$0.51	$0.51	$0.50	$0.48	$0.48	$0.09
Cash distribution adjustment period	'18 days	'	'	'	'	'	'	'	'
Fourth Quarter 2011 Prorated [Member]	'	'	'	'	'	'	'	'	'
Cash Distributions to Unitholders [Line Items]	'	'	'	'	'	'	'	'	'
Distribution per unit	0.0929	'	'	'	'	'	'	'	'
Fourth Quarter 2011 [Member]	'	'	'	'	'	'	'	'	'
Cash Distributions to Unitholders [Line Items]	'	'	'	'	'	'	'	'	'
Distribution per unit	0.475	'	'	'	'	'	'	'	'

Earnings_Per_Units_Calculation

Earnings Per Units - Calculation of Earnings (Loss) Per Unit (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Unit [Abstract]	'	'	'	'
Net income (loss) attributable to partners	($43,293)	($25,332)	($2,136)	($4,692)
Less: General partner's 0.1% interest in net income (loss)	-43	-25	-2	-5
Less: IDRs	-40	'	-40	'
Net income (loss) available to limited partners	($43,210)	($25,307)	($2,094)	($4,687)
Weighted average limited partner units outstanding:	'	'	'	'
Common units	39,195	16,941	35,954	16,880
Subordinated units	5,361	5,361	5,361	5,361
Total	44,556	22,302	41,315	22,241
Basic and diluted EPU	($0.97)	($1.13)	($0.05)	($0.21)

Earnings_Per_Units_Calculation1

Earnings Per Units - Calculation of Earnings (Loss) Per Unit (Parenthetical) (Detail)	3 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Unit [Abstract]	'	'
General partner's interest in net income, percentage	0.10%	0.10%

EquityBased_Awards_Summary_of_

Equity-Based Awards - Summary of Information Regarding Restricted Common Unit Awards (Detail) (Restricted Stock [Member], USD $)	9 Months Ended
	Sep. 30, 2013
Restricted Stock [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Restricted common units outstanding at December 31, 2012	285,609
Granted, Number of Units	515,947
Forfeited, Number of Units	-11,734
Vested, Number of Units	-91,154
Restricted common units outstanding at September 30, 2013	698,668
Restricted common units outstanding, Weighted Average Grant Date Fair Value per unit, at December 31, 2012	$18.08
Granted, Weighted-Average Grant Date Fair Value per Unit	$18.81
Forfeited, Weighted-Average Grant Date Fair Value per Unit	$17.24
Vested, Weighted-Average Grant Date Fair Value per Unit	$18.31
Restricted common units outstanding, Weighted Average Grant Date Fair Value per unit, at, September 30, 2013	$18.60

EquityBased_Awards_Summary_of_1

Equity-Based Awards - Summary of Information Regarding Restricted Common Unit Awards (Parenthetical) (Detail) (Restricted Stock [Member], USD $)	Sep. 30, 2013
In Millions, except Per Share data, unless otherwise specified
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Aggregate grant date fair value of restricted common unit awards issued	$9.70
Minimum [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Range of grant date market price	$18.33
Maximum [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Range of grant date market price	$19.88

EquityBased_Awards_Summary_of_2

Equity-Based Awards - Summary of Amount of Compensation Expense Recognized (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'	'
Compensation expense	$1,237	$418	$2,322	$993

Equitybased_Awards_Additional_

Equity-based Awards - Additional Information (Detail) (Restricted Common Units [Member], USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013
Restricted Common Units [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Unrecognized compensation cost	$11.30
Weighted-average period of unrecognized compensation cost	'2 years 4 months 21 days

Related_Party_Transactions_Rel

Related Party Transactions - Related Party Transactions Reflected in Accompanying Statements of Operations (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Related Party Transaction [Abstract]	'	'	'	'
Related party transactions expenses	$3,151	$1,614	$7,880	$4,747

Related_Party_Transactions_Add

Related Party Transactions - Additional Information (Detail) (USD $)

1 Months Ended

9 Months Ended

1 Months Ended

Mar. 28, 2013

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Oct. 10, 2013

Oct. 01, 2013

Oct. 01, 2013

Oct. 01, 2013

Mar. 28, 2013

Sep. 30, 2013

Nov. 01, 2013

Nov. 01, 2013

OLLC $1.0 billion multi-year revolving credit facility [Member]

OLLC $1.0 billion multi-year revolving credit facility [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Cinco Group acquisition [Member]

WHT [Member]

Memorial Resource [Member]

Memorial Resource [Member]

Memorial Resource [Member]

OLLC $1.0 billion multi-year revolving credit facility [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Common Units Pledged [Member]

Subordinated Units Pledged [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Related Party Transaction Due From To Related Party [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Common Control Acquisition Purchase Price

'

'

'

'

'

'

'

'

$603,000,000

$200,000,000

'

'

'

Date of acquisition common control

'

'

'

'

'

'

'

'

1-Oct-13

'

'

'

'

Revolving credit facility, current capacity

'

1,000,000,000

'

'

'

'

'

'

'

'

'

'

'

Revolving credit facility, maximum borrowing capacity

'

'

'

1,000,000,000

'

'

2,000,000,000

'

'

'

'

'

'

Borrowing base

580,000,000

480,000,000

580,000,000

480,000,000

460,000,000

'

'

920,000,000

'

'

'

'

'

Borrowing base reduced amount

100,000,000

'

'

'

'

75,000,000

'

'

'

'

'

'

'

Working capital and other customary adjustments

'

'

'

'

'

'

'

'

'

4,000,000

'

'

'

Date of acquisition common control

'

'

'

'

'

'

'

'

'

28-Mar-13

'

'

'

Effective date of common control acquisition

'

1-Jan-13

'

'

'

'

'

'

'

'

'

'

'

Amount receivable under management agreement

'

'

'

'

'

'

'

'

'

'

400,000

'

'

Management fee paid by WHT per month

$200,000

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit facility collateral number of partnership units

'

'

'

'

'

'

'

'

'

'

'

7,061,294

5,360,912

Related_Party_Transactions_Sch

Related Party Transactions - Schedule of Net Assets Recorded by Partnership (Common Control Acquisitions) (Detail) (WHT [Member], USD $)	Mar. 28, 2013
In Thousands, unless otherwise specified
WHT [Member]	'
Related Party Transaction Acquisition Of Net Assets [Abstract]	'
Cash and cash equivalents	$1,354
Accounts receivable	3,866
Short-term derivative instruments, net	1,206
Prepaid expenses and other current assets	98
Oil and natural gas properties, net	192,280
Long-term derivative instruments, net	3,528
Accrued liabilities	-3,494
Asset retirement obligations	-2,753
Credit facilities	-89,300
Other long-term liabilities	-111
Net assets	$106,674

Related_Party_Transactions_Sch1

Related Party Transactions - Schedule of Amount of General and Administrative Costs and Expenses Recognized (Detail) (Omnibus Agreement [Member], USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Omnibus Agreement [Member]	'	'	'	'
Related Party Transaction Due From To Related Party [Line Items]	'	'	'	'
General and administrative costs and expenses under omnibus agreement	$2,988	$526	$6,239	$1,185

Related_Party_Transactions_Sch2

Related Party Transactions - Schedule of Summarized General and Administrative Costs and Expenses (Detail) (REO [Member], USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2012	Sep. 30, 2012
REO [Member]	'	'
Related Party Transaction Due From To Related Party [Line Items]	'	'
Management fees	$345	$1,500

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
Commitments And Contingencies Disclosure [Abstract]	'	'
Environmental reserves, total	$0.50	$1.10
Maximum remaining obligation	$13.20	'

Commitments_and_Contingencies_2

Commitments and Contingencies - Gross Held-to-Maturity Investments (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Held To Maturity Securities [Abstract]	'
Less: Outside working interest owners share	($60,968)
Amortized Cost	65,390
Less: Outside working interest owners share unrealized gain (loss)	-93
Unrealized Gain (Loss)	101
Less: Outside working interest owners share fair market value	-61,061
Fair Market Value	65,491
U.S. Bank Money Market Cash Equivalent [Member]	'
Held To Maturity Securities [Abstract]	'
Amortized Cost	103,285
Unrealized Gain (Loss)	'
Fair Market Value	103,285
U.S. Government Treasury Note 1.75% Coupon [Member]	'
Held To Maturity Securities [Abstract]	'
Amortized Cost	23,073
Unrealized Gain (Loss)	194
Fair Market Value	$23,267

Commitments_and_Contingencies_3

Commitments and Contingencies - Gross Held-to-Maturity Investments (Parenthetical) (Detail)	Sep. 30, 2013
Held To Maturity Securities [Abstract]	'
Coupon Rate, Two	1.75%
U.S. Government Treasury Note 1.75% Coupon [Member]	'
Held To Maturity Securities [Abstract]	'
Maturity date of treasury notes	31-Mar-14

Commitments_and_Contingencies_4

Commitments and Contingencies - Minimum Balances Attributable to Net Working Interest (Detail) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
June 30, 2014 [Member]	'
Asset retirement obligations	'
Minimum balances attributable to REO's net working interest	$68,310
June 30, 2015 [Member]	'
Asset retirement obligations	'
Minimum balances attributable to REO's net working interest	72,450
June 30, 2016 [Member]	'
Asset retirement obligations	'
Minimum balances attributable to REO's net working interest	76,590
December 31, 2016 [Member]	'
Asset retirement obligations	'
Minimum balances attributable to REO's net working interest	$78,660

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (Subsequent Event [Member], USD $)	1 Months Ended
In Millions, except Share data, unless otherwise specified	Oct. 08, 2013	Oct. 10, 2013
		7.625% Senior Notes [Member]
Subsequent Event [Line Items]	'	'
Common units issued	16,675,000	'
Common units issued upon full exercise of underwriters option to purchase	2,175,000	'
Public offering price	$19.90	'
Net proceeds from equity offering	$319.20	'
Face amount of 7.625% Senior Notes due 2021 at time of issuance	'	$300
Senior notes issued at a discount or premium to par	'	97.00%