Chord Energy (CHRD) 10-Q 7 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	1-May-15
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Trading Symbol	OAS
Entity Registrant Name	Oasis Petroleum Inc.
Entity Central Index Key	1486159
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		139,199,814

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheet (Unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
ASSETS
Cash and cash equivalents	$10,188	$45,811
Accounts receivable — oil and gas revenues	112,785	130,934
Accounts receivable — joint interest partners	130,384	175,537
Inventory	21,956	21,354
Prepaid expenses	16,954	14,273
Derivative instruments	253,320	302,159
Other current assets	1,000	6,539
Total current assets	546,587	696,607
Property, plant and equipment
Oil and gas properties (successful efforts method)	6,187,638	5,966,140
Other property and equipment	356,940	313,439
Less: accumulated depreciation, depletion, amortization and impairment	-1,215,216	-1,092,793
Total property, plant and equipment, net	5,329,362	5,186,786
Derivative instruments	0	13,348
Deferred costs and other assets	40,988	41,671
Total assets	5,916,937	5,938,412
LIABILITIES AND STOCKHOLDERS’ EQUITY
Accounts payable	9,339	20,958
Revenues and production taxes payable	210,478	209,890
Accrued liabilities	314,211	410,379
Accrued interest payable	24,677	49,786
Deferred income taxes	77,746	97,499
Advances from joint interest partners	5,788	6,616
Total current liabilities	642,239	795,128
Long-term debt	2,365,000	2,700,000
Deferred income taxes	539,146	526,770
Asset retirement obligations	42,980	42,097
Other liabilities	3,327	2,116
Total liabilities	3,592,692	4,066,111
Commitments and contingencies (Note 14)
Stockholders’ equity
Common stock, $0.01 par value: 300,000,000 shares authorized; 139,619,087 and 101,627,296 shares issued at March 31, 2015 and December 31, 2014, respectively	1,372	1,001
Treasury stock, at cost: 397,732 and 285,677 shares at March 31, 2015 and December 31, 2014, respectively	-12,191	-10,671
Additional paid-in capital	1,478,336	1,007,202
Retained earnings	856,728	874,769
Total stockholders’ equity	2,324,245	1,872,301
Total liabilities and stockholders’ equity	$5,916,937	$5,938,412

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheet (Unaudited) (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	139,619,087	101,627,296
Treasury stock, shares	397,732	285,677

Condensed_Consolidated_Stateme

Condensed Consolidated Statement of Operations (Unaudited) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Revenues
Oil and gas revenues	$173,859	$331,847
Well services and midstream revenues	6,528	17,672
Total revenues	180,387	349,519
Expenses
Lease operating expenses	39,125	39,989
Well services and midstream operating expenses	1,952	10,920
Marketing, transportation and gathering expenses	7,278	5,186
Production taxes	16,621	31,803
Depreciation, depletion and amortization	118,478	91,272
Exploration expenses	843	380
Rig termination	1,080	0
Impairment of oil and gas properties	5,321	762
General and administrative expenses	23,324	23,520
Total expenses	214,022	203,832
Gain on sale of properties	0	183,393
Operating income (loss)	-33,635	329,080
Other income (expense)
Net gain (loss) on derivative instruments	47,072	-17,603
Interest expense, net of capitalized interest	-38,784	-40,158
Other income (expense)	-70	153
Total other income (expense)	8,218	-57,608
Income (loss) before income taxes	-25,417	271,472
Income tax benefit (expense)	7,376	-101,519
Net income (loss)	($18,041)	$169,953
Earnings (loss) per share:
Basic (in dollars per share)	($0.17)	$1.71
Diluted (in dollars per share)	($0.17)	$1.70
Weighted average shares outstanding:
Basic (in shares)	109,303	99,560
Diluted (in shares)	109,303	100,049

Condensed_Consolidated_Stateme1

Condensed Consolidated Statement of Changes in Stockholders' Equity (Unaudited) (USD $)	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in-Capital [Member]	Retained Earnings [Member]
In Thousands, except Share data, unless otherwise specified
Balance at Dec. 31, 2014	$1,872,301	$1,001	($10,671)	$1,007,202	$874,769
Balance, shares at Dec. 31, 2014		101,342,000	286,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock	463,218	368		462,850
Issuance of common stock, shares		36,800,000
Stock-based compensation	8,287			8,287
Stock-based compensation, shares		1,191,000
Vesting of restricted shares		3		-3
Treasury stock – tax withholdings	-1,520		-1,520
Treasury stock - tax withholdings, shares		-112,000	112,000
Net loss	-18,041				-18,041
Balance at Mar. 31, 2015	$2,324,245	$1,372	($12,191)	$1,478,336	$856,728
Balance, shares at Mar. 31, 2015		139,221,000	398,000

Condensed_Consolidated_Stateme2

Condensed Consolidated Statement of Cash Flows (Unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income (loss)	($18,041)	$169,953
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, depletion and amortization	118,478	91,272
Gain on sale of properties	0	-183,393
Impairment of oil and gas properties	5,321	762
Deferred income taxes	-7,376	98,753
Derivative instruments	-47,072	17,603
Stock-based compensation expenses	7,606	4,505
Deferred financing costs amortization and other	1,655	1,487
Working capital and other changes:
Change in accounts receivable	63,313	-9,275
Change in inventory	-602	790
Change in prepaid expenses	1,892	-14,259
Change in other current assets	5,539	-29
Change in other assets	0	-1,593
Change in accounts payable and accrued liabilities	-42,341	29,007
Change in other current liabilities	0	2,766
Change in other liabilities	-11	-82
Net cash provided by operating activities	88,361	208,267
Cash flows from investing activities:
Capital expenditures	-359,113	-280,895
Proceeds from sale of properties	0	321,943
Costs related to sale of properties	0	-2,010
Derivative settlements	109,259	-2,239
Advances from joint interest partners	-828	-1,898
Net cash provided by (used in) investing activities	-250,682	34,901
Cash flows from financing activities:
Proceeds from sale of common stock	463,218	0
Proceeds from revolving credit facility	145,000	0
Principal payments on revolving credit facility	-480,000	-275,570
Purchases of treasury stock	-1,520	-3,025
Other	0	-176
Net cash provided by (used in) financing activities	126,698	-278,771
Decrease in cash and cash equivalents	-35,623	-35,603
Cash and cash equivalents:
Beginning of period	45,811	91,901
End of period	10,188	56,298
Supplemental non-cash transactions:
Change in accrued capital expenditures	-90,189	39,516
Change in asset retirement obligations	$1,413	($128)

Organization_and_Operations_of

Organization and Operations of the Company	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Organization and Operations of the Company	Organization and Operations of the Company
	Organization
	Oasis Petroleum Inc. (together with its subsidiaries, “Oasis” or the “Company”) was formed on February 25, 2010, pursuant to the laws of the State of Delaware, to become a holding company for Oasis Petroleum LLC (“OP LLC”), the Company’s predecessor, which was formed as a Delaware limited liability company on February 26, 2007. In connection with its initial public offering in June 2010 and related corporate reorganization, the Company acquired all of the outstanding membership interests in OP LLC in exchange for shares of the Company’s common stock. Oasis Petroleum North America LLC (“OPNA”), a Delaware limited liability company formed in 2007, conducts the Company’s domestic oil and natural gas exploration and production activities. In 2011, the Company formed Oasis Well Services LLC (“OWS”), a Delaware limited liability company, to provide well services to OPNA, and Oasis Petroleum Marketing LLC (“OPM”), a Delaware limited liability company, to provide marketing services to OPNA. In 2013, the Company formed Oasis Midstream Services LLC (“OMS”), a Delaware limited liability company, to provide midstream services to OPNA.
	Nature of Business
	The Company is an independent exploration and production company focused on the acquisition and development of unconventional oil and natural gas resources in the Williston Basin. The Company’s proved and unproved oil and natural gas properties are located in the North Dakota and Montana areas of the Williston Basin and are owned by OPNA. The Company also operates an oil and gas marketing business (OPM), a well services business (OWS) and a midstream services business (OMS), all of which are complementary to its primary development and production activities. Both OWS and OMS are separate reportable business segments, while OPM is included in the Company’s exploration and production segment.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies
	Basis of Presentation
	The accompanying condensed consolidated financial statements of the Company include the accounts of Oasis and its wholly-owned subsidiaries. All significant intercompany transactions have been eliminated in consolidation. The accompanying condensed consolidated financial statements of the Company have not been audited by the Company’s independent registered public accounting firm, except that the Condensed Consolidated Balance Sheet at December 31, 2014 is derived from audited financial statements. Certain reclassifications of prior year balances have been made to conform such amounts to current year classifications. These reclassifications have no impact on net income. In the opinion of management, all adjustments, consisting of normal recurring adjustments necessary for the fair presentation, have been included. Management has made certain estimates and assumptions that affect reported amounts in the condensed consolidated financial statements and disclosures of contingencies. Actual results may differ from those estimates. The results for interim periods are not necessarily indicative of annual results.
	These interim financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain disclosures have been condensed or omitted from these financial statements. Accordingly, they do not include all of the information and notes required by accounting principles generally accepted in the United States of America (“GAAP”) for complete consolidated financial statements and should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014 (“2014 Annual Report”).
	As an oil and natural gas producer, the Company’s revenue, profitability and future growth are substantially dependent upon the prevailing and future prices for oil and natural gas, which are dependent upon numerous factors beyond its control such as economic, political and regulatory developments and competition from other energy sources. The energy markets have historically been very volatile, and there can be no assurance that oil and natural gas prices will not be subject to wide fluctuations in the future. Crude oil prices declined significantly in the latter part of 2014 and have remained low in 2015. As a result of lower oil prices, the Company has significantly decreased its planned 2015 capital expenditures as compared to 2014 and is currently concentrating its drilling activities in certain areas that are the most economic in the Williston Basin. An extended period of low prices for oil could have a material adverse effect on the Company’s financial position, results of operations, cash flows and quantities of oil and natural gas reserves that may be economically produced.
	Significant Accounting Policies
	There have been no material changes to the Company’s critical accounting policies and estimates from those disclosed in the 2014 Annual Report other than those noted below.
	Recent Accounting Pronouncements
	Revenue recognition. In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”). The objective of ASU 2014-09 is greater consistency and comparability across industries by using a five-step model to recognize revenue from customer contracts. ASU 2014-09 also contains some new disclosure requirements under GAAP and is effective for interim and annual reporting periods beginning after December 15, 2016. The Company is currently evaluating the effect that adopting this new guidance will have on its financial position, cash flows and results of operations.
	Going concern. In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Presentation of Financial Statements - Going Concern (“ASU 2014-15”). ASU 2014-15 codifies in GAAP management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. ASU 2014-15 is effective for interim and annual reporting periods beginning after December 15, 2016. The Company does not expect the adoption of this guidance to have a material impact on its financial position, cash flows or results of operations.
	Extraordinary items. In January 2015, the FASB issued Accounting Standards Update No. 2015-01, Income Statement - Extraordinary and Unusual Items (“ASU 2015-01”). ASU 2015-01 removes the concept of extraordinary items from GAAP. Under existing guidance, an entity is required to separately disclose extraordinary items, net of tax, in the income statement after income from continuing operations if an event or transaction is of an unusual nature and occurs infrequently. This separate, net-of-tax presentation will no longer be allowed. ASU 2015-01 is effective for interim and annual reporting periods beginning after December 15, 2015. The Company does not expect the adoption of this guidance to have a material impact on its financial position, cash flows or results of operations.
	Debt issuance costs. In April 2015, the FASB issued Accounting Standards Update No. 2015-03, Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”). ASU 2015-03 requires debt issuance costs to be presented in the balance sheet as a direct deduction from the carrying value of the associated debt liability, consistent with the presentation of debt discount, but it does not affect the recognition or measurement of debt issuance costs. ASU 2015-03 is effective for interim and annual reporting periods beginning after December 15, 2015. The Company does not expect the adoption of this guidance to have a material impact on its financial position, cash flows or results of operations.

Inventory

Inventory	3 Months Ended
	Mar. 31, 2015
Inventory Disclosure [Abstract]
Inventory	Inventory
	Equipment and materials consist primarily of proppant, chemicals, tubular goods, well equipment to be used in future drilling or repair operations and well fracturing equipment. Crude oil inventory includes oil in tank and linefill. Inventory is stated at the lower of cost or market value with cost determined on an average cost method. Inventory consists of the following:
		March 31, 2015		December 31, 2014
		(In thousands)
	Equipment and materials	$	14,219	$	14,225
	Crude oil inventory	7,737		7,129
	Total inventory	$	21,956	$	21,354

Property_Plant_and_Equipment

Property, Plant and Equipment	3 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, Plant and Equipment
	The following table sets forth the Company’s property, plant and equipment:
		31-Mar-15			31-Dec-14
		(In thousands)
	Proved oil and gas properties(1)	$	5,467,976		$	5,156,875
	Less: Accumulated depreciation, depletion, amortization and impairment	(1,157,925		)	(1,043,121		)
	Proved oil and gas properties, net	4,310,051			4,113,754
	Unproved oil and gas properties	719,662			809,265
	Total oil and gas properties, net	5,029,713			4,923,019
	Other property and equipment	356,940			313,439
	Less: Accumulated depreciation	(57,291		)	(49,672		)
	Other property and equipment, net	299,649			263,767
	Total property, plant and equipment, net	$	5,329,362		$	5,186,786
	__________________
	-1	Included in the Company’s proved oil and gas properties are estimates of future asset retirement costs of $37.5 million and $36.9 million at March 31, 2015 and December 31, 2014, respectively.
	Impairment. As a result of expiring leases and periodic assessments of unproved properties, the Company recorded non-cash impairment charges on its unproved oil and natural gas properties of $5.3 million and $0.8 million for the three months ended March 31, 2015 and 2014, respectively. No impairment charges on proved oil and gas properties were recorded for the three months ended March 31, 2015 or 2014.
	Divestiture. On March 5, 2014, the Company completed the sale of certain non-operated properties in and around its Sanish position for cash proceeds of approximately $324.9 million, which includes customary post close adjustments. The Company recognized a $187.0 million gain on sale of properties in its Consolidated Statement of Operations for the year ended December 31, 2014.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements
	In accordance with the FASB’s authoritative guidance on fair value measurements, the Company’s financial assets and liabilities are measured at fair value on a recurring basis. The Company recognizes its non-financial assets and liabilities, such as asset retirement obligations (“ARO”) and proved oil and natural gas properties upon impairment, at fair value on a non-recurring basis.
	As defined in the authoritative guidance, fair value is the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). To estimate fair value, the Company utilizes market data or assumptions that market participants would use in pricing the asset or liability, including assumptions about risk and the risks inherent in the inputs to the valuation technique. These inputs can be readily observable, market corroborated or generally unobservable.
	The authoritative guidance establishes a fair value hierarchy that prioritizes the inputs used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (“Level 1” measurements) and the lowest priority to unobservable inputs (“Level 3” measurements). The three levels of the fair value hierarchy are as follows:
	Level 1 — Unadjusted quoted prices are available in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis.
	Level 2 — Pricing inputs, other than unadjusted quoted prices in active markets included in Level 1, are either directly or indirectly observable as of the reporting date. Level 2 includes those financial instruments that are valued using models or other valuation methodologies. These models are primarily industry-standard models that consider various assumptions, including quoted forward prices for commodities, time value, volatility factors and current market and contractual prices for the underlying instruments, as well as other relevant economic measures. Substantially all of these assumptions are observable in the marketplace throughout the full term of the instrument and can be derived from observable data or are supported by observable levels at which transactions are executed in the marketplace.
	Level 3 — Pricing inputs are generally less observable from objective sources, requiring internally developed valuation methodologies that result in management’s best estimate of fair value.
	Financial Assets and Liabilities
	As required, financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input requires judgment and may affect the valuation of fair value assets and liabilities and their placement within the fair value hierarchy levels. The following tables set forth by level within the fair value hierarchy the Company’s financial assets and liabilities that were accounted for at fair value on a recurring basis:
		At fair value as of March 31, 2015
		Level 1		Level 2		Level 3		Total
		(In thousands)
	Assets:
	Money market funds	$	742	$	—	$	—	$	742
	Commodity derivative instruments (see Note 6)	—		253,320		—		253,320
	Total assets	$	742	$	253,320	$	—	$	254,062
		At fair value as of December 31, 2014
		Level 1		Level 2		Level 3		Total
		(In thousands)
	Assets:
	Money market funds	$	742	$	—	$	—	$	742
	Commodity derivative instruments (see Note 6)	—		315,507		—		315,507
	Total assets	$	742	$	315,507	$	—	$	316,249
	The Level 1 instruments presented in the tables above consist of money market funds included in cash and cash equivalents on the Company’s Condensed Consolidated Balance Sheet at March 31, 2015 and December 31, 2014. The Company’s money market funds represent cash equivalents backed by the assets of high-quality major banks and financial institutions. The Company identifies the money market funds as Level 1 instruments because the money market funds have daily liquidity, quoted prices for the underlying investments can be obtained, and there are active markets for the underlying investments.
	The Level 2 instruments presented in the tables above consist of commodity derivative instruments, which include oil collars, swaps and deferred premium puts. The fair values of the Company’s commodity derivative instruments are based upon a third-party preparer’s calculation using mark-to-market valuation reports provided by the Company’s counterparties for monthly settlement purposes to determine the valuation of its derivative instruments. The Company has the third-party preparer evaluate other readily available market prices for its derivative contracts, as there is an active market for these contracts. The third-party preparer performs its independent valuation using a moment matching method similar to Turnbull-Wakeman for Asian options. The significant inputs used are crude oil prices, volatility, skew, discount rate and the contract terms of the derivative instruments. However, the Company does not have access to the specific proprietary valuation models or inputs used by its counterparties or third-party preparer. The Company compares the third-party preparer’s valuation to counterparty valuation statements, investigating any significant differences, and analyzes monthly valuation changes in relation to movements in crude oil forward price curves. The determination of the fair value for derivative instruments also incorporates a credit adjustment for non-performance risk, as required by GAAP. The Company calculates the credit adjustment for derivatives in a net asset position using current credit default swap values for each counterparty. The credit adjustment for derivatives in a net liability position is based on the Company’s market credit spread. Based on these calculations, the Company recorded an adjustment to reduce the fair value of its net derivative asset by $0.4 million and $0.6 million at March 31, 2015 and December 31, 2014, respectively.
	Fair Value of Other Financial Instruments
	The Company’s financial instruments, including certain cash and cash equivalents, accounts receivable and accounts payable, are carried at cost, which approximates fair value due to the short-term maturity of these instruments. At March 31, 2015, the Company’s cash equivalents were all Level 1 assets.
	The carrying amount of the Company’s long-term debt reported in the Condensed Consolidated Balance Sheet at March 31, 2015 was $2,365.0 million, which includes $2,200.0 million of senior unsecured notes and $165.0 million of borrowings under the revolving credit facility (see Note 7 – Long-Term Debt). The fair value of the Company’s senior unsecured notes, which are publicly traded and therefore categorized as Level 1 liabilities, was $2,141.0 million at March 31, 2015.
	Non-Financial Assets and Liabilities
	Asset retirement obligations. The carrying amount of ARO in the Company’s Condensed Consolidated Balance Sheet at March 31, 2015 was $43.7 million (see Note 8 – Asset Retirement Obligations). The Company determines its ARO by calculating the present value of estimated cash flows related to the liability. Estimating the future ARO requires management to make estimates and judgments regarding the timing and existence of a liability, as well as what constitutes adequate restoration when considering current regulatory requirements. Inherent in the fair value calculation are numerous assumptions and judgments, including the ultimate costs, inflation factors, credit adjusted discount rates, timing of settlement and changes in the legal, regulatory, environmental and political environments. These assumptions represent Level 3 inputs. To the extent future revisions to these assumptions impact the fair value of the existing ARO liability, a corresponding adjustment is made to the related asset.
	Impairment. The Company reviews its proved oil and natural gas properties for impairment whenever events and circumstances indicate that a decline in the recoverability of their carrying value may have occurred. The Company estimates the expected undiscounted future cash flows of its proved oil and natural gas properties then compares such undiscounted future cash flows to the carrying amount of the proved oil and natural gas properties to determine if the carrying amount is recoverable. If the carrying amount exceeds the estimated undiscounted future cash flows, the Company will adjust the carrying amount of the oil and natural gas properties to fair value. The factors used to determine fair value are subject to management’s judgment and expertise and include, but are not limited to, recent sales prices of comparable properties, the present value of future cash flows, net of estimated operating and development costs using estimates of proved reserves, future commodity pricing, future production estimates, anticipated capital expenditures and various discount rates commensurate with the risk and current market conditions associated with realizing the expected cash flows projected. These assumptions represent Level 3 inputs. No impairment charges on proved oil and natural gas properties were recorded for the three months ended March 31, 2015 or 2014.

Derivative_Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments
	The Company utilizes derivative financial instruments to manage risks related to changes in oil prices. As of March 31, 2015, the Company utilized two-way costless collar options, swaps and deferred premium puts to reduce the volatility of oil prices on a significant portion of its future expected oil production. A two-way collar is a combination of options: a sold call and a purchased put. The purchased put establishes a minimum price (floor) and the sold call establishes a maximum price (ceiling) the Company will receive for the volumes under contract. A swap is a sold call and a purchased put established at the same price (both ceiling and floor). For the deferred premium puts, the Company agrees to pay a premium to the counterparty at the time of settlement. At settlement, if the NYMEX West Texas Intermediate (“WTI”) crude oil index price is below the floor price of the put, the Company receives the difference between the floor price and the WTI price multiplied by the contract volumes, less the premium. If the WTI price settles at or above the floor price of the put, the Company pays only the premium.
	All derivative instruments are recorded on the Company’s Condensed Consolidated Balance Sheet as either assets or liabilities measured at fair value (see Note 5 – Fair Value Measurements). The Company has not designated any derivative instruments as hedges for accounting purposes and does not enter into such instruments for speculative trading purposes. If a derivative does not qualify as a hedge or is not designated as a hedge, the changes in fair value are recognized in the other income (expense) section of the Company’s Condensed Consolidated Statement of Operations as a net gain or loss on derivative instruments. The Company’s cash flow is only impacted when the actual settlements under the derivative contracts result in making a payment to or receiving a payment from the counterparty. These cash settlements represent the cumulative gains and losses on the Company’s derivative instruments and do not include a recovery of costs that were paid to acquire or modify the derivative instruments that were settled. Cash settlements are reflected as investing activities in the Company’s Condensed Consolidated Statement of Cash Flows.
	As of March 31, 2015, the Company had the following outstanding commodity derivative instruments, all of which settle monthly based on the average WTI crude oil index price:
															Weighted Average Deferred Premium
	Settlement	Derivative		Total Notional			Weighted Average Prices										Fair Value
	Period	Instrument		Amount of Oil			Swap				Floor		Ceiling				Asset (Liability)
				(Barrels)			($/Barrel)										(In thousands)
	2015	Two-way collars		1,402,000							$	86.52	$	102.86			$	57,100
	2015	Swaps		3,381,000			$	89.36									152,359
	2015	Deferred premium puts		546,000							$	90			$	2.55	28,188
	2016	Two-way collars		155,000							$	86	$	103.42			4,717
	2016	Swaps		372,000			$	85.27									10,956
																	$	253,320
	The following table summarizes the location and fair value of all outstanding commodity derivative instruments recorded in the Company’s Condensed Consolidated Balance Sheet for the periods presented:
				Fair Value Asset (Liability)
	Commodity	Balance Sheet Location		March 31, 2015				31-Dec-14
				(In thousands)
	Crude oil	Derivative instruments — current assets		$	253,320			$	302,159
	Crude oil	Derivative instruments — non-current assets		—				13,348
	Total derivative instruments			$	253,320			$	315,507
	The following table summarizes the location and amounts of gains and losses from the Company’s commodity derivative instruments for the periods presented:
		Three Months Ended March 31,
	Statement of Operations Location	2015				2014
		(In thousands)
	Net gain (loss) on derivative instruments	$	47,072			$	(17,603	)
	In accordance with the FASB’s authoritative guidance on disclosures about offsetting assets and liabilities, the Company is required to disclose both gross and net information about instruments and transactions eligible for offset in the statement of financial position as well as instruments and transactions subject to an agreement similar to a master netting agreement. The Company’s derivative instruments are presented as assets and liabilities on a net basis by counterparty, as all counterparty contracts provide for net settlement. No margin or collateral balances are deposited with counterparties, and as such, gross amounts are offset to determine the net amounts presented in the Company’s Condensed Consolidated Balance Sheet.
	The following tables summarize gross and net information about the Company’s commodity derivative instruments for the periods presented:
	Offsetting of Derivative Assets	Gross Amounts of Recognized Assets				Gross Amounts Offset				Net Amounts of Assets Presented
						in the Balance Sheet				in the Balance Sheet
		(In thousands)
	As of March 31, 2015	$	268,107			$	(14,787	)		$	253,320
	As of December 31, 2014	331,121				(15,614		)		315,507
	Offsetting of Derivative Liabilities	Gross Amounts of Recognized Liabilities				Gross Amounts Offset				Net Amounts of Liabilities Presented
						in the Balance Sheet				in the Balance Sheet
		(In thousands)
	As of March 31, 2015	$	14,787			$	(14,787	)		$	—
	As of December 31, 2014	15,614				(15,614		)		—

LongTerm_Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt
	Senior unsecured notes. During 2013, the Company issued $1,000.0 million of 6.875% senior unsecured notes due March 15, 2022 (the “2022 Notes”), which resulted in aggregate net proceeds to the Company of $983.6 million. The Company used the proceeds from the 2022 Notes to fund the acquisition of oil and gas properties. During 2011 and 2012, the Company issued $400.0 million of 7.25% senior unsecured notes due February 1, 2019 (the “2019 Notes”), $400.0 million of 6.5% senior unsecured notes due November 1, 2021 (the “2021 Notes”) and $400.0 million of 6.875% senior unsecured notes due January 15, 2023 (the “2023 Notes”), which resulted in aggregate net proceeds to the Company of $1,175.8 million. The Company used the proceeds from these notes to fund its exploration, development and acquisition program and for general corporate purposes. Interest on the 2019 Notes, the 2021 Notes, the 2022 Notes and the 2023 Notes (collectively, the “Notes”) is payable semi-annually in arrears.
	The Notes were issued under indentures containing provisions that are substantially the same, as amended and supplemented by supplemental indentures (collectively, the “Indentures”), among the Company, along with its material subsidiaries (the “Guarantors”), and U.S. Bank National Association, as trustee. The Notes are guaranteed on a senior unsecured basis by the Company’s Guarantors. These guarantees are full and unconditional and joint and several among the Guarantors, subject to certain customary release provisions, as follows:
	•	in connection with any sale or other disposition of all or substantially all of the assets of that Guarantor (including by way of merger or consolidation) to a person that is not (either before or after giving effect to such transaction) the Company or a Restricted Subsidiary (as defined in the Indentures) of the Company;
	•	in connection with any sale or other disposition of the capital stock of that Guarantor (including by way of merger or consolidation) to a person that is not (either before or after giving effect to such transaction) the Company or a Restricted Subsidiary of the Company, such that, immediately after giving effect to such transaction, such Guarantor would no longer constitute a subsidiary of the Company;
	•	if the Company designates any Restricted Subsidiary that is a Guarantor to be an unrestricted subsidiary in accordance with the Indenture;
	•	upon legal defeasance or satisfaction and discharge of the Indenture; or
	•	upon the liquidation or dissolution of a Guarantor, provided no event of default occurs under the Indentures as a result thereof.
	Prior to certain dates, the Company has certain options to redeem up to 35% of the Notes at a certain redemption price based on a percentage of the principal amount, plus accrued and unpaid interest to the redemption date, with the proceeds of certain equity offerings so long as the redemption occurs within 180 days of completing such equity offering and at least 65% of the aggregate principal amount of the Notes remains outstanding after such redemption. Prior to certain dates, the Company has the option to redeem some or all of the Notes for cash at certain redemption prices equal to a certain percentage of their principal amount plus an applicable make-whole premium and accrued and unpaid interest to the redemption date. The Company estimates that the fair value of these redemption options is immaterial at March 31, 2015 and December 31, 2014.
	The Indentures restrict the Company’s ability and the ability of certain of its subsidiaries to: (i) incur additional debt or enter into sale and leaseback transactions; (ii) pay distributions on, redeem or repurchase equity interests; (iii) make certain investments; (iv) incur liens; (v) enter into transactions with affiliates; (vi) merge or consolidate with another company; and (vii) transfer and sell assets. These covenants are subject to certain exceptions and qualifications. If at any time when the Notes are rated investment grade by both Moody’s Investors Service, Inc. and Standard & Poor’s Ratings Services and no Default (as defined in the Indentures) has occurred and is continuing, many of such covenants will terminate and the Company and its subsidiaries will cease to be subject to such covenants.
	The Indentures contain customary events of default, including:
	•	default in any payment of interest on any Note when due, continued for 30 days;
	•	default in the payment of principal or premium, if any, on any Note when due;
	•	failure by the Company to comply with its other obligations under the Indentures, in certain cases subject to notice and grace periods;
	•	payment defaults and accelerations with respect to other indebtedness of the Company and its Restricted Subsidiaries in the aggregate principal amount of $10.0 million or more;
	•	certain events of bankruptcy, insolvency or reorganization of the Company or a Significant Subsidiary (as defined in the Indentures) or group of Restricted Subsidiaries that, taken together, would constitute a Significant Subsidiary;
	•	failure by the Company or any Significant Subsidiary or group of Restricted Subsidiaries that, taken together, would constitute a Significant Subsidiary to pay certain final judgments aggregating in excess of $10.0 million within 60 days; and
	•	any guarantee of the Notes by a Guarantor ceases to be in full force and effect, is declared null and void in a judicial proceeding or is denied or disaffirmed by its maker.
	Senior secured revolving line of credit. On April 5, 2013, the Company, as parent, and OPNA, as borrower, entered into a second amended and restated credit agreement (the “Second Amended Credit Facility”), which has a maturity date of April 5, 2018. The Second Amended Credit Facility is restricted to the borrowing base, which is reserve-based and subject to semi-annual redeterminations on April 1 and October 1 of each year. As of March 31, 2015, the borrowing base was $2,000.0 million; however, the Company elected to limit the aggregate commitment of the lenders under the Second Amended Credit Facility (the “Lenders”) to $1,500.0 million. The overall senior secured line of credit under the Second Amended Credit Facility is $2,500.0 million as of March 31, 2015. On April 13, 2015, the Company entered into an amendment to the Second Amended Credit Facility in order to extend the maturity date of the Second Amended Credit Facility, increase the aggregate elected commitment amounts of the Lenders and provide for the scheduled redetermination of the borrowing base (see Note 16 – Subsequent Events).
	Borrowings under the Second Amended Credit Facility are collateralized by perfected first priority liens and security interests on substantially all of the Company’s assets, including mortgage liens on oil and natural gas properties having at least 80% of the reserve value as determined by reserve reports.
	Borrowings under the Second Amended Credit Facility are subject to varying rates of interest based on (1) the total outstanding borrowings (including the value of all outstanding letters of credit) in relation to the borrowing base and (2) whether the loan is a London interbank offered rate (“LIBOR”) loan or a domestic bank prime interest rate loan (defined in the Second Amended Credit Facility as an Alternate Based Rate or “ABR” loan). As of March 31, 2015, any outstanding LIBOR and ABR loans bore their respective interest rates plus the applicable margin indicated in the following table:
	Ratio of Total Outstanding Borrowings to Borrowing Base		Applicable Margin		Applicable Margin
			for LIBOR Loans		for ABR Loans
	Less than .25 to 1		1.5	%	0	%
	Greater than or equal to .25 to 1 but less than .50 to 1		1.75	%	0.25	%
	Greater than or equal to .50 to 1 but less than .75 to 1		2	%	0.5	%
	Greater than or equal to .75 to 1 but less than .90 to 1		2.25	%	0.75	%
	Greater than or equal to .90 to 1		2.5	%	1	%
	An ABR loan may be repaid at any time before the scheduled maturity of the Second Amended Credit Facility upon the Company providing advance notification to the Lenders. Interest is paid quarterly on ABR loans based on the number of days an ABR loan is outstanding as of the last business day in March, June, September and December. The Company has the option to convert an ABR loan to a LIBOR-based loan upon providing advance notification to the Lenders. The minimum available loan term is one month and the maximum loan term is six months for LIBOR-based loans. Interest for LIBOR loans is paid upon maturity of the loan term. Interim interest is paid every three months for LIBOR loans that have loan terms greater than three months in duration. At the end of a LIBOR loan term, the Second Amended Credit Facility allows the Company to elect to repay the borrowing, continue a LIBOR loan with the same or a differing loan term or convert the borrowing to an ABR loan.
	On a quarterly basis, the Company pays a 0.375% (as of March 31, 2015) annualized commitment fee on the average amount of borrowing base capacity not utilized during the quarter and fees calculated on the average amount of letter of credit balances outstanding during the quarter.
	As of March 31, 2015, the Second Amended Credit Facility contained covenants that included, among others:
	•	a prohibition against incurring debt, subject to permitted exceptions;
	•	a prohibition against making dividends, distributions and redemptions, subject to permitted exceptions;
	•	a prohibition against making investments, loans and advances, subject to permitted exceptions;
	•	restrictions on creating liens and leases on the assets of the Company and its subsidiaries, subject to permitted exceptions;
	•	restrictions on merging and selling assets outside the ordinary course of business;
	•	restrictions on use of proceeds, investments, transactions with affiliates or change of principal business;
	•	a provision limiting oil and natural gas derivative financial instruments;
	•	a requirement that the Company maintain a ratio of consolidated EBITDAX (as defined in the Second Amended Credit Facility) to consolidated Interest Expense (as defined in the Second Amended Credit Facility) of no less than 2.5 to 1.0 for the four quarters ended on the last day of each quarter; and
	•	a requirement that the Company maintain a Current Ratio (as defined in the Second Amended Credit Facility) of consolidated current assets (including unused borrowing base capacity and with exclusions as described in the Second Amended Credit Facility) to consolidated current liabilities (with exclusions as described in the Second Amended Credit Facility) of no less than 1.0 to 1.0 as of the last day of any fiscal quarter.
	The Second Amended Credit Facility contains customary events of default. If an event of default occurs and is continuing, the Lenders may declare all amounts outstanding under the Second Amended Credit Facility to be immediately due and payable.
	As of March 31, 2015, the Company had $165.0 million of LIBOR loans and $5.2 million of outstanding letters of credit issued under the Second Amended Credit Facility, resulting in an unused borrowing base committed capacity of $1,329.8 million. As of March 31, 2015 and December 31, 2014, the weighted average interest rate on borrowings outstanding under the Second Amended Credit Facility was 1.7% and 1.9%, respectively. The Company was in compliance with the financial covenants of the Second Amended Credit Facility as of March 31, 2015.
	Deferred financing costs. As of March 31, 2015, the Company had $33.9 million of deferred financing costs related to the Notes and the Second Amended Credit Facility. The deferred financing costs are included in deferred costs and other assets on the Company’s Condensed Consolidated Balance Sheet at March 31, 2015 and are being amortized over the respective terms of the Notes and the Second Amended Credit Facility. Amortization of deferred financing costs was $1.6 million for each of the three months ended March 31, 2015 and 2014. These costs are included in interest expense on the Company’s Condensed Consolidated Statement of Operations.

Asset_Retirement_Obligations

Asset Retirement Obligations	3 Months Ended
	Mar. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations
	The following table reflects the changes in the Company’s ARO during the three months ended March 31, 2015:
		(In thousands)
	Balance at December 31, 2014	$	42,549
	Liabilities incurred during period	372
	Liabilities settled during period	(41		)
	Accretion expense during period(1)	537
	Revisions to estimates	241
	Balance at March 31, 2015	$	43,658
	___________________
	-1	Included in depreciation, depletion and amortization on the Company’s Condensed Consolidated Statement of Operations.
	At March 31, 2015, the current portion of the total ARO balance was approximately $0.7 million and is included in accrued liabilities on the Company’s Condensed Consolidated Balance Sheet.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	For the three months ended March 31, 2015, the Company recorded an income tax benefit of $7.4 million resulting in a 29.0% effective tax rate as a percentage of its pre-tax loss for the quarter. The Company’s income tax expense for the three months ended March 31, 2014 was recorded at 37.4% of pre-tax net income. While the 2014 effective tax rate was consistent with the statutory tax rate applicable to the U.S. and the blended state rate for the states in which the Company conducts business, the rate for the three months ended March 31, 2015 was lower due to permanent differences between the compensation amounts expensed for book purposes versus the amounts deductible for income tax purposes.
	The Company’s calculated tax benefit was $10.6 million, or 41.6% as a percentage of its pre-tax loss for the three months ended March 31, 2015, before applying discrete income taxes related to the impact of stock compensation vesting during the first quarter of 2015 at stock prices lower than the grant date values. As of March 31, 2015, the Company did not have any uncertain tax positions requiring adjustments to its tax liability.
	The Company had deferred tax assets for its federal and state tax loss carryforwards at March 31, 2015 recorded in deferred income taxes. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that some portion or all of the deferred tax assets will not be realized. As of March 31, 2015, management determined that a valuation allowance was not required for the tax loss carryforwards as they are expected to be fully utilized before expiration.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation
	Restricted stock awards. The Company has granted restricted stock awards to employees and directors under its Amended and Restated 2010 Long Term Incentive Plan, the majority of which vest over a three-year period. The fair value of restricted stock grants is based on the closing sales price of the Company’s common stock on the date of grant. Compensation expense is recognized ratably over the requisite service period. For the three months ended March 31, 2015, the Company assumed annual forfeiture rates by employee group ranging from 0% to 16.9% based on the Company’s forfeiture history for this type of award.
	During the three months ended March 31, 2015, employees and non-employee directors of the Company were granted restricted stock awards equal to 1,219,820 shares of common stock with a $13.09 weighted average grant date per share value. Stock-based compensation expense recorded for restricted stock awards for the three months ended March 31, 2015 and 2014 was $6.8 million and $3.9 million, respectively, and is included in general and administrative expenses on the Company’s Condensed Consolidated Statement of Operations.
	Performance share units. The Company has granted performance share units (“PSUs”) to officers of the Company under its Amended and Restated 2010 Long Term Incentive Plan. The PSUs are awards of restricted stock units, and each PSU that is earned represents the right to receive one share of the Company’s common stock. For the three months ended March 31, 2015, the Company assumed annual forfeiture rates by employee group ranging from 2.4% to 4.9% based on the Company’s forfeiture history for the officer employee groups receiving PSUs.
	During the three months ended March 31, 2015, officers of the Company were granted 425,590 PSUs with an $11.20 weighted average grant date per share value. Stock-based compensation expense recorded for PSUs for the three months ended March 31, 2015 and 2014 was $0.8 million and $0.6 million, respectively, and is included in general and administrative expenses on the Company’s Condensed Consolidated Statement of Operations.
	Each grant of PSUs is subject to a designated three-year initial performance period. The number of PSUs to be earned is subject to a market condition, which is based on a comparison of the total shareholder return (“TSR”) achieved with respect to shares of the Company’s common stock against the TSR achieved by a defined peer group at the end of the performance period. Depending on the Company’s TSR performance relative to the defined peer group, award recipients will earn between 0% and 200% of the initial PSUs granted. If less than 200% of the initial PSUs granted are earned at the end of the initial three-year performance period, then the performance period will be extended an additional year to give the award recipients the opportunity to earn up to an aggregate of 200% of the initial PSUs granted.
	The Company accounted for these PSUs as equity awards pursuant to the FASB’s authoritative guidance for share-based payments. The aggregate grant date fair value of the market-based awards was determined using a Monte Carlo simulation model, which results in an expected percentage of PSUs earned. The fair value of these PSUs is recognized on a straight-line basis over the performance period. As it is probable that a portion of the awards will be earned during the extended performance period, the grant date fair value will be amortized over four years. However, if 200% of the initial PSUs granted are earned at the end of the initial performance period, then the remaining compensation expense will be accelerated in order to be fully recognized over three years. All compensation expense related to the PSUs will be recognized if the requisite performance period is fulfilled, even if the market condition is not achieved.
	The Monte Carlo simulation model uses assumptions regarding random projections and must be repeated numerous times to achieve a probabilistic assessment. The key valuation assumptions for the Monte Carlo model are the forecast period, initial value, risk-free interest rate, volatility and correlation coefficients. The risk-free interest rate is the U.S. Treasury bond rate on the date of grant that corresponds to the extended performance period. The initial value is the average of the volume weighted average prices for the 30 trading days prior to the start of the performance cycle for the Company and each of its peers. Volatility is the standard deviation of the average percentage change in stock price over a historical period for the Company and each of its peers. The correlation coefficients are measures of the strength of the linear relationship between and amongst the Company and its peers estimated based on historical stock price data.
	The following assumptions were used for the Monte Carlo model to determine the grant date fair value and associated stock-based compensation expense of the PSUs granted during the three months ended March 31, 2015:
	Forecast period (years)	4
	Risk-free interest rate	0.99	%
	Oasis stock price volatility	50.11	%
	For the PSUs granted during the three months ended March 31, 2015, the Monte Carlo simulation model resulted in 86% of PSUs expected to be earned over the extended performance period.

Common_Stock

Common Stock	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Common Stock	Common Stock
	On March 9, 2015, the Company completed a public offering of 36,800,000 shares of its common stock (including 4,800,000 shares issued pursuant to the underwriters’ option to purchase additional common stock), par value $0.01 per share, at an offering price of $12.80 per share. Net proceeds from the offering were $463.1 million, after deducting underwriting discounts and commissions and estimated offering expenses, of which $368,000 is included in common stock and $462.7 million is included in additional paid-in capital on the Company’s Condensed Consolidated Balance Sheet. The Company used the net proceeds to repay outstanding indebtedness under its Second Amended Credit Facility and for general corporate purposes. The offering was made pursuant to an effective shelf registration statement on Form S-3 filed with the SEC on July 15, 2014.

Earnings_Per_Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share	Earnings (Loss) Per Share
	Basic earnings (loss) per share is computed by dividing income available to common stockholders by the weighted average number of shares outstanding for the periods presented. The calculation of diluted earnings (loss) per share includes the impact of potentially dilutive non-vested restricted shares and PSUs outstanding during the periods presented, unless their effect is anti-dilutive. There are no adjustments made to income (loss) available to common stockholders in the calculation of diluted earnings (loss) per share.
	The following is a calculation of the basic and diluted weighted-average shares outstanding for the three months ended March 31, 2015 and 2014:
		Three Months Ended March 31,
		2015	2014
		(In thousands)
	Basic weighted average common shares outstanding	109,303	99,560
	Dilution effect of stock awards at end of period(1)	—	489
	Diluted weighted average common shares outstanding	109,303	100,049
	Anti-dilutive stock-based compensation awards	3,046	1,047
	___________________
	-1	No unvested stock awards were included in computing loss per share for the three months ended March 31, 2015 because the effect was anti-dilutive.

Business_Segment_Information

Business Segment Information	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Business Segment Information	Business Segment Information
	The Company’s exploration and production segment is engaged in the acquisition and development of oil and natural gas properties and includes the complementary marketing services provided by OPM. Revenues for the exploration and production segment are primarily derived from the sale of oil and natural gas production. In the first quarter of 2012, the Company began its well services business segment (OWS) to perform completion services for the Company’s oil and natural gas wells operated by OPNA. Revenues for the well services segment are derived from providing well completion services, well completion product sales and tool rentals. In the first quarter of 2013, the Company formed its midstream services business segment (OMS) to perform salt water disposal and other midstream services for the Company’s oil and natural gas wells operated by OPNA. Revenues for the midstream segment are primarily derived from salt water transport, salt water disposal and fresh water sales. The revenues and expenses related to work performed by OWS and OMS for OPNA’s working interests are eliminated in consolidation, and only the revenues and expenses related to non-affiliated working interest owners are included in the Company’s Condensed Consolidated Statement of Operations. These segments represent the Company’s three current operating units, each offering different products and services. The Company’s corporate activities have been allocated to the supported business segments accordingly.
	Management evaluates the performance of the Company’s business segments based on operating income, which is defined as segment operating revenues less operating expenses, including depreciation, depletion and amortization. The following table summarizes financial information for the Company’s business segments for the periods presented:
		Exploration and			Well Services			Midstream Services			Eliminations			Consolidated
		Production
		(In thousands)
	Three months ended March 31, 2015:
	Revenues from external customers	$	173,859		$	2,708		$	3,820		$	—		$	180,387
	Inter-segment revenues	—			48,197			13,822			(62,019		)	—
	Total revenues	173,859			50,905			17,642			(62,019		)	180,387
	Operating income (loss)	(42,247		)	9,610			9,308			(10,306		)	(33,635		)
	Other income (expense)	8,239			(2		)	(19		)	—			8,218
	Income (loss) before income taxes	$	(34,008	)	$	9,608		$	9,289		$	(10,306	)	$	(25,417	)
	Three months ended March 31, 2014:
	Revenues from external customers	$	331,847		$	15,827		$	1,845		$	—		$	349,519
	Inter-segment revenues	—			36,579			7,508			(44,087		)	—
	Total revenues	331,847			52,406			9,353			(44,087		)	349,519
	Operating income	322,945			13,452			4,632			(11,949		)	329,080
	Other income (expense)	(57,660		)	52			—			—			(57,608		)
	Income before income taxes	$	265,285		$	13,504		$	4,632		$	(11,949	)	$	271,472
	As of March 31, 2015:
	Property, plant and equipment, net	$	5,194,649		$	56,270		$	207,713		$	(129,270	)	$	5,329,362
	Total assets	5,758,513			330,239			265,627			(437,442		)	5,916,937
	As of December 31, 2014:
	Property, plant and equipment, net	$	5,074,588		$	58,767		$	172,394		$	(118,963	)	$	5,186,786
	Total assets	5,802,295			281,844			212,685			(358,412		)	5,938,412

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	Included below is a discussion of various future commitments of the Company as of March 31, 2015. The commitments under these arrangements are not recorded in the accompanying Condensed Consolidated Balance Sheet. The amounts disclosed represent undiscounted cash flows on a gross basis, and no inflation elements have been applied.
	Lease obligations. The Company’s total rental commitments under leases for office space and other property and equipment at March 31, 2015 were $32.5 million.
	Drilling contracts. As a result of its lowered 2015 capital expenditure program, the Company elected to early terminate a drilling rig contract and recorded $1.1 million of rig termination expense in its Condensed Consolidated Statement of Operations for the three months ended March 31, 2015.
	As of March 31, 2015, the Company had certain drilling rig contracts with initial terms greater than one year. In the event of early termination under these contracts, the Company would be obligated to pay approximately $10.2 million as of March 31, 2015 for the days remaining through the end of the primary terms of the contracts.
	Volume commitment agreements. As of March 31, 2015, the Company had certain agreements with an aggregate requirement to deliver a minimum quantity of approximately 31.0 MMBbl and 6.6 Bcf from its Williston Basin project area within specified timeframes, all of which are less than ten years. Future commitments under these agreements were approximately $190.5 million as of March 31, 2015.
	Purchase agreements. As of March 31, 2015, the Company had certain agreements for the purchase of fresh water and well completion services equipment with an aggregate future commitment of approximately $52.8 million.
	Cost sharing agreements. As of March 31, 2015, the Company had certain agreements to share the cost to construct and install electrical facilities. The Company’s estimated future commitment under these agreements was $8.1 million as of March 31, 2015.
	Litigation. The Company is party to various legal and/or regulatory proceedings from time to time arising in the ordinary course of business. While the ultimate outcome and impact to the Company cannot be predicted with certainty, the Company believes that all such matters are without merit and involve amounts which, if resolved unfavorably, either individually or in the aggregate, will not have a material adverse effect on its financial condition, results of operations or cash flows. When the Company determines that a loss is probable of occurring and is reasonably estimable, the Company accrues an undiscounted liability for such contingencies based on its best estimate using information available at the time. The Company discloses contingencies where an adverse outcome may be material, or in the judgment of management, the matter should otherwise be disclosed.
	On July 6, 2013, a freight train operated by Montreal, Maine and Atlantic Railway (“MMA”) carrying crude oil (the “Train”) derailed in Lac-Mégantic, Quebec. In March 2014, Oasis Petroleum Inc. and OP LLC were added to a group of over fifty named defendants, including other crude oil producers as well as the Canadian Pacific Railway, MMA and certain of its affiliates, owners and transloaders of the crude oil carried by the Train, several lessors of tank cars, and the Attorney General of Canada, in a motion filed in Quebec Superior Court to authorize a class-action lawsuit seeking economic, compensatory and punitive damages, as well as costs for claims arising out of the derailment of the Train (Yannick Gagne, etc., et al. v. Rail World, Inc., etc., et al., Case No. 48006000001132) (the “Class-Action”). The motion generally alleges wrongful death and negligence in the failure to provide for the proper and safe transportation of crude oil. The Company believes that all claims against Oasis Petroleum Inc. and OP LLC in connection with the derailment of the Train in Lac-Mégantic, Quebec are without merit.
	On August 7, 2013, MMA filed for bankruptcy protection in the Quebec Superior Court and the United States Bankruptcy Court in Bangor, Maine (together, the “Bankruptcy Actions”). The trustees appointed in the Bankruptcy Actions have negotiated settlement agreements, which are pending approval by the Quebec Superior Court and the United States Bankruptcy Court, with the majority of the named defendants in the Class-Action, including Oasis Petroleum Inc. and OP LLC.  If approved, pursuant to the settlement agreement, Oasis Petroleum Inc. and OP LLC have agreed to contribute to the compensation fund established for those suffering losses as a result of the Lac-Megantic derailment. The Company has determined that such contributions are fully covered by the Company’s insurance policies. Furthermore, the settlement agreements would bar future litigation against Oasis Petroleum Inc. and OP LLC in Canada and the United States arising out of the Lac-Megantic derailment.

Condensed_Consolidating_Financ

Condensed Consolidating Financial Information	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Condensed Consolidating Financial Information	Condensed Consolidating Financial Information
	The Notes (see Note 7) are guaranteed on a senior unsecured basis by the Guarantors, which are 100% owned by the Company. These guarantees are full and unconditional and joint and several among the Guarantors. Certain of the Company’s immaterial wholly-owned subsidiaries do not guarantee the Notes (“Non-Guarantor Subsidiaries”).
	The following financial information reflects consolidating financial information of the parent company, Oasis Petroleum Inc. (“Issuer”), and its Guarantors on a combined basis, prepared on the equity basis of accounting. The Non-Guarantor Subsidiaries are immaterial and, therefore, not presented separately. The information is presented in accordance with the requirements of Rule 3-10 under the SEC’s Regulation S-X. The financial information may not necessarily be indicative of results of operations, cash flows or financial position had the Guarantors operated as independent entities. The Company has not presented separate financial and narrative information for each of the Guarantors because it believes such financial and narrative information would not provide any additional information that would be material in evaluating the sufficiency of the Guarantors.
	Condensed Consolidating Balance Sheet
		31-Mar-15
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
		(In thousands)
	ASSETS
	Cash and cash equivalents	$	774		$	9,414		$	—		$	10,188
	Accounts receivable	—			243,169			—			243,169
	Accounts receivable – affiliates	1,032			143,517			(144,549		)	—
	Other current assets	148			293,082			—			293,230
	Oil and gas properties (successful efforts method)	—			6,187,638			—			6,187,638
	Other property and equipment	—			356,940			—			356,940
	Accumulated depreciation, depletion, amortization and impairment	—			(1,215,216		)	—			(1,215,216		)
	Investments in and advances to subsidiaries	4,499,571			—			(4,499,571		)	—
	Other long-term assets	190,812			12,674			(162,498		)	40,988
	Total assets	$	4,692,337		$	6,031,218		$	(4,806,618	)	$	5,916,937
	LIABILITIES AND EQUITY
	Accounts payable	$	—		$	9,339		$	—		$	9,339
	Accounts payable – affiliates	143,517			1,032			(144,549		)	—
	Other current liabilities	24,575			608,325			—			632,900
	Long-term debt	2,200,000			165,000			—			2,365,000
	Other long-term liabilities	—			747,951			(162,498		)	585,453
	Common stock	1,372			—			—			1,372
	Other equity	2,322,873			4,499,571			(4,499,571		)	2,322,873
	Total liabilities and equity	$	4,692,337		$	6,031,218		$	(4,806,618	)	$	5,916,937
	Condensed Consolidating Balance Sheet
		31-Dec-14
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
		(In thousands)
	ASSETS
	Cash and cash equivalents	$	776		$	45,035		$	—		$	45,811
	Accounts receivable	—			306,471			—			306,471
	Accounts receivable – affiliates	781			91,459			(92,240		)	—
	Prepaid expenses	297			13,976			—			14,273
	Other current assets	—			330,052			—			330,052
	Oil and gas properties (successful efforts method)	—			5,966,140			—			5,966,140
	Other property and equipment	—			313,439			—			313,439
	Accumulated depreciation, depletion, amortization and impairment	—			(1,092,793		)	—			(1,092,793		)
	Investments in and advances to subsidiaries	4,032,494			—			(4,032,494		)	—
	Other long-term assets	178,752			25,584			(149,317		)	55,019
	Total assets	$	4,213,100		$	5,999,363		$	(4,274,051	)	$	5,938,412
	LIABILITIES AND EQUITY
	Accounts payable	$	—		$	20,958		$	—		$	20,958
	Accounts payable – affiliates	91,459			781			(92,240		)	—
	Other current liabilities	49,340			724,830			—			774,170
	Long-term debt	2,200,000			500,000			—			2,700,000
	Other long-term liabilities	—			720,300			(149,317		)	570,983
	Equity	1,872,301			4,032,494			(4,032,494		)	1,872,301
	Total liabilities and equity	$	4,213,100		$	5,999,363		$	(4,274,051	)	$	5,938,412
	Condensed Consolidating Statement of Operations
		Three Months Ended March 31, 2015
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
		(In thousands)
	Total revenues	$	—		$	180,387		$	—		$	180,387
	Total operating expenses	8,619			205,403			—			214,022
	Operating loss	(8,619		)	(25,016		)	—			(33,635		)
Equity in earnings in subsidiaries	12,619			—			(12,619		)	—
Other income (expense)	(35,222		)	43,440			—			8,218
Income (loss) before income taxes	(31,222		)	18,424			(12,619		)	(25,417		)
Income tax benefit (expense)	13,181			(5,805		)	—			7,376
Net income (loss)	$	(18,041	)	$	12,619		$	(12,619	)	$	(18,041	)
Condensed Consolidating Statement of Operations
	Three Months Ended March 31, 2014
	Parent/			Combined			Intercompany			Consolidated
	Issuer			Guarantor			Eliminations
				Subsidiaries
	(In thousands)
Total revenues	$	—		$	349,519		$	—		$	349,519
General and administrative expenses	5,612			17,908			—			23,520
Other operating expenses	—			180,312			—			180,312
Gain on sale of properties	—			183,393			—			183,393
Operating income (loss)	(5,612		)	334,692			—			329,080
Equity in earnings in subsidiaries	196,933			—			(196,933		)	—
Interest expense, net of capitalized interest	(37,424		)	(2,734		)	—			(40,158		)
Other income (expense)	3			(17,453		)	—			(17,450		)
Income before income taxes	153,900			314,505			(196,933		)	271,472
Income tax benefit (expense)	16,053			(117,572		)	—			(101,519		)
Net income	$	169,953		$	196,933		$	(196,933	)	$	169,953
Condensed Consolidating Statement of Cash Flows
	Three Months Ended March 31, 2015
	Parent/			Combined			Intercompany			Consolidated
	Issuer			Guarantor			Eliminations
				Subsidiaries
	(In thousands)
Net cash provided by (used in) operating activities	$	(7,988	)	$	96,349		$	—		$	88,361
Cash flows from investing activities:
Capital expenditures	—			(359,113		)	—			(359,113		)
Derivative settlements	—			109,259			—			109,259
Other investing activities	—			(828		)	—			(828		)
Net cash used in investing activities	—			(250,682		)	—			(250,682		)
Cash flows from financing activities:
Proceeds from sale of common stock	463,218			—			—			463,218
Proceeds from revolving credit facility	—			145,000			—			145,000
Principal payments on revolving credit facility	—			(480,000		)	—			(480,000		)
Other financing activities	(455,232		)	453,712			—			(1,520		)
Net cash provided by financing activities	7,986			118,712			—			126,698
Decrease in cash and cash equivalents	(2		)	(35,621		)	—			(35,623		)
Cash and cash equivalents at beginning of period	776			45,035			—			45,811
Cash and cash equivalents at end of period	$	774		$	9,414		$	—		$	10,188
Condensed Consolidating Statement of Cash Flows
	Three Months Ended March 31, 2014
	Parent/			Combined			Intercompany			Consolidated
	Issuer			Guarantor			Eliminations
				Subsidiaries
	(In thousands)
Net cash provided by (used in) operating activities	$	(56,630	)	$	264,897		$	—		$	208,267
Cash flows from investing activities:
Capital expenditures	—			(280,895		)	—			(280,895		)
Proceeds from sale of properties	—			321,943			—			321,943
Other investing activities	—			(6,147		)	—			(6,147		)
Net cash provided by investing activities	—			34,901			—			34,901
Cash flows from financing activities:
Principal payments on revolving credit facility	—			(275,570		)	—			(275,570		)
Other financing activities	23,289			(26,490		)	—			(3,201		)
Net cash provided by (used in) financing activities	23,289			(302,060		)	—			(278,771		)
Decrease in cash and cash equivalents	(33,341		)	(2,262		)	—			(35,603		)
Cash and cash equivalents at beginning of period	34,277			57,624			—			91,901
Cash and cash equivalents at end of period	$	936		$	55,362		$	—		$	56,298

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events
	The Company has evaluated the period after the balance sheet date, noting no subsequent events or transactions that required recognition or disclosure in the financial statements, other than as noted below.
	Credit facility amendment. On April 13, 2015, the Company entered into its third amendment to the Second Amended Credit Facility (the “Third Amendment”), which extended the maturity date of the Second Amended Credit Facility to April 13, 2020, provided that the 2019 Notes are retired or refinanced 90 days prior to their maturity. In connection with the Third Amendment, the Lenders completed their regular semi-annual redetermination of the borrowing base scheduled for April 1, 2015, resulting in a borrowing base decrease from $2,000.0 million to $1,700.0 million. The Company increased the Lenders’ aggregate elected commitment from $1,500.0 million to $1,525.0 million. The Lenders’ aggregate commitment can be increased to the full $1,700.0 million borrowing base by increasing the commitment of one or more Lenders. The Third Amendment also increased the Lenders in the bank group to 18 financial institutions supporting the Company’s borrowing base facility.
	Derivative instruments. In April and May 2015, the Company entered into new swap agreements with a weighted average price of $61.28 per barrel for total notional amounts of 1,102,000 barrels, 703,000 barrels and 31,000 barrels, which settle in 2015, 2016 and 2017, respectively, based on the WTI crude oil index price. These derivative instruments do not qualify for and were not designated as hedging instruments for accounting purposes.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation
	The accompanying condensed consolidated financial statements of the Company include the accounts of Oasis and its wholly-owned subsidiaries. All significant intercompany transactions have been eliminated in consolidation. The accompanying condensed consolidated financial statements of the Company have not been audited by the Company’s independent registered public accounting firm, except that the Condensed Consolidated Balance Sheet at December 31, 2014 is derived from audited financial statements. Certain reclassifications of prior year balances have been made to conform such amounts to current year classifications. These reclassifications have no impact on net income. In the opinion of management, all adjustments, consisting of normal recurring adjustments necessary for the fair presentation, have been included. Management has made certain estimates and assumptions that affect reported amounts in the condensed consolidated financial statements and disclosures of contingencies. Actual results may differ from those estimates. The results for interim periods are not necessarily indicative of annual results.
	These interim financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain disclosures have been condensed or omitted from these financial statements. Accordingly, they do not include all of the information and notes required by accounting principles generally accepted in the United States of America (“GAAP”) for complete consolidated financial statements and should be read in conjunction with the Company’s audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014 (“2014 Annual Report”).
Significant Accounting Policies	Recent Accounting Pronouncements
	Revenue recognition. In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”). The objective of ASU 2014-09 is greater consistency and comparability across industries by using a five-step model to recognize revenue from customer contracts. ASU 2014-09 also contains some new disclosure requirements under GAAP and is effective for interim and annual reporting periods beginning after December 15, 2016. The Company is currently evaluating the effect that adopting this new guidance will have on its financial position, cash flows and results of operations.
	Going concern. In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Presentation of Financial Statements - Going Concern (“ASU 2014-15”). ASU 2014-15 codifies in GAAP management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to provide related footnote disclosures. ASU 2014-15 is effective for interim and annual reporting periods beginning after December 15, 2016. The Company does not expect the adoption of this guidance to have a material impact on its financial position, cash flows or results of operations.
	Extraordinary items. In January 2015, the FASB issued Accounting Standards Update No. 2015-01, Income Statement - Extraordinary and Unusual Items (“ASU 2015-01”). ASU 2015-01 removes the concept of extraordinary items from GAAP. Under existing guidance, an entity is required to separately disclose extraordinary items, net of tax, in the income statement after income from continuing operations if an event or transaction is of an unusual nature and occurs infrequently. This separate, net-of-tax presentation will no longer be allowed. ASU 2015-01 is effective for interim and annual reporting periods beginning after December 15, 2015. The Company does not expect the adoption of this guidance to have a material impact on its financial position, cash flows or results of operations.
	Debt issuance costs. In April 2015, the FASB issued Accounting Standards Update No. 2015-03, Simplifying the Presentation of Debt Issuance Costs (“ASU 2015-03”). ASU 2015-03 requires debt issuance costs to be presented in the balance sheet as a direct deduction from the carrying value of the associated debt liability, consistent with the presentation of debt discount, but it does not affect the recognition or measurement of debt issuance costs. ASU 2015-03 is effective for interim and annual reporting periods beginning after December 15, 2015. The Company does not expect the adoption of this guidance to have a material impact on its financial position, cash flows or results of operations.

Inventory_Tables

Inventory (Tables)	3 Months Ended
	Mar. 31, 2015
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventory consists of the following:
		March 31, 2015		December 31, 2014
		(In thousands)
	Equipment and materials	$	14,219	$	14,225
	Crude oil inventory	7,737		7,129
	Total inventory	$	21,956	$	21,354

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 31, 2015
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment	The following table sets forth the Company’s property, plant and equipment:
		31-Mar-15			31-Dec-14
		(In thousands)
	Proved oil and gas properties(1)	$	5,467,976		$	5,156,875
	Less: Accumulated depreciation, depletion, amortization and impairment	(1,157,925		)	(1,043,121		)
	Proved oil and gas properties, net	4,310,051			4,113,754
	Unproved oil and gas properties	719,662			809,265
	Total oil and gas properties, net	5,029,713			4,923,019
	Other property and equipment	356,940			313,439
	Less: Accumulated depreciation	(57,291		)	(49,672		)
	Other property and equipment, net	299,649			263,767
	Total property, plant and equipment, net	$	5,329,362		$	5,186,786
	__________________
	-1	Included in the Company’s proved oil and gas properties are estimates of future asset retirement costs of $37.5 million and $36.9 million at March 31, 2015 and December 31, 2014, respectively.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Hierarchy of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables set forth by level within the fair value hierarchy the Company’s financial assets and liabilities that were accounted for at fair value on a recurring basis:
		At fair value as of March 31, 2015
		Level 1		Level 2		Level 3		Total
		(In thousands)
	Assets:
	Money market funds	$	742	$	—	$	—	$	742
	Commodity derivative instruments (see Note 6)	—		253,320		—		253,320
	Total assets	$	742	$	253,320	$	—	$	254,062
		At fair value as of December 31, 2014
		Level 1		Level 2		Level 3		Total
		(In thousands)
	Assets:
	Money market funds	$	742	$	—	$	—	$	742
	Commodity derivative instruments (see Note 6)	—		315,507		—		315,507
	Total assets	$	742	$	315,507	$	—	$	316,249

Derivative_Instruments_Tables

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Outstanding Commodity Derivative Instruments	As of March 31, 2015, the Company had the following outstanding commodity derivative instruments, all of which settle monthly based on the average WTI crude oil index price:
															Weighted Average Deferred Premium
	Settlement	Derivative		Total Notional			Weighted Average Prices										Fair Value
	Period	Instrument		Amount of Oil			Swap				Floor		Ceiling				Asset (Liability)
				(Barrels)			($/Barrel)										(In thousands)
	2015	Two-way collars		1,402,000							$	86.52	$	102.86			$	57,100
	2015	Swaps		3,381,000			$	89.36									152,359
	2015	Deferred premium puts		546,000							$	90			$	2.55	28,188
	2016	Two-way collars		155,000							$	86	$	103.42			4,717
	2016	Swaps		372,000			$	85.27									10,956
																	$	253,320
Schedule of Location and Fair Value of Outstanding Commodity Derivative Instruments	The following table summarizes the location and fair value of all outstanding commodity derivative instruments recorded in the Company’s Condensed Consolidated Balance Sheet for the periods presented:
				Fair Value Asset (Liability)
	Commodity	Balance Sheet Location		March 31, 2015				31-Dec-14
				(In thousands)
	Crude oil	Derivative instruments — current assets		$	253,320			$	302,159
	Crude oil	Derivative instruments — non-current assets		—				13,348
	Total derivative instruments			$	253,320			$	315,507
Gains and Losses from Commodity Derivative Instruments	The following table summarizes the location and amounts of gains and losses from the Company’s commodity derivative instruments for the periods presented:
		Three Months Ended March 31,
	Statement of Operations Location	2015				2014
		(In thousands)
	Net gain (loss) on derivative instruments	$	47,072			$	(17,603	)
Summary of Gross and Net Information about Commodity Derivative Assets	The following tables summarize gross and net information about the Company’s commodity derivative instruments for the periods presented:
	Offsetting of Derivative Assets	Gross Amounts of Recognized Assets				Gross Amounts Offset				Net Amounts of Assets Presented
						in the Balance Sheet				in the Balance Sheet
		(In thousands)
	As of March 31, 2015	$	268,107			$	(14,787	)		$	253,320
	As of December 31, 2014	331,121				(15,614		)		315,507
Summary of Gross and Net Information about Commodity Derivative Liabilities
	Offsetting of Derivative Liabilities	Gross Amounts of Recognized Liabilities				Gross Amounts Offset				Net Amounts of Liabilities Presented
						in the Balance Sheet				in the Balance Sheet
		(In thousands)
	As of March 31, 2015	$	14,787			$	(14,787	)		$	—
	As of December 31, 2014	15,614				(15,614		)		—

LongTerm_Debt_Tables

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Schedule of Long-Term Debt Interest Rate	As of March 31, 2015, any outstanding LIBOR and ABR loans bore their respective interest rates plus the applicable margin indicated in the following table:
	Ratio of Total Outstanding Borrowings to Borrowing Base	Applicable Margin		Applicable Margin
		for LIBOR Loans		for ABR Loans
	Less than .25 to 1	1.5	%	0	%
	Greater than or equal to .25 to 1 but less than .50 to 1	1.75	%	0.25	%
	Greater than or equal to .50 to 1 but less than .75 to 1	2	%	0.5	%
	Greater than or equal to .75 to 1 but less than .90 to 1	2.25	%	0.75	%
	Greater than or equal to .90 to 1	2.5	%	1	%

Asset_Retirement_Obligations_T

Asset Retirement Obligations (Tables)	3 Months Ended
	Mar. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Changes in Asset Retirement Obligations	The following table reflects the changes in the Company’s ARO during the three months ended March 31, 2015:
		(In thousands)
	Balance at December 31, 2014	$	42,549
	Liabilities incurred during period	372
	Liabilities settled during period	(41		)
	Accretion expense during period(1)	537
	Revisions to estimates	241
	Balance at March 31, 2015	$	43,658
	___________________
	-1	Included in depreciation, depletion and amortization on the Company’s Condensed Consolidated Statement of Operations.

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Assumptions	The following assumptions were used for the Monte Carlo model to determine the grant date fair value and associated stock-based compensation expense of the PSUs granted during the three months ended March 31, 2015:
	Forecast period (years)	4
	Risk-free interest rate	0.99	%
	Oasis stock price volatility	50.11	%

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Schedule of Weighted-Average Number of Shares Outstanding	The following is a calculation of the basic and diluted weighted-average shares outstanding for the three months ended March 31, 2015 and 2014:
		Three Months Ended March 31,
		2015	2014
		(In thousands)
	Basic weighted average common shares outstanding	109,303	99,560
	Dilution effect of stock awards at end of period(1)	—	489
	Diluted weighted average common shares outstanding	109,303	100,049
	Anti-dilutive stock-based compensation awards	3,046	1,047

Business_Segment_Information_T

Business Segment Information (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Summarized Financial Information of Segments	The following table summarizes financial information for the Company’s business segments for the periods presented:
		Exploration and			Well Services			Midstream Services			Eliminations			Consolidated
		Production
		(In thousands)
	Three months ended March 31, 2015:
	Revenues from external customers	$	173,859		$	2,708		$	3,820		$	—		$	180,387
	Inter-segment revenues	—			48,197			13,822			(62,019		)	—
	Total revenues	173,859			50,905			17,642			(62,019		)	180,387
	Operating income (loss)	(42,247		)	9,610			9,308			(10,306		)	(33,635		)
	Other income (expense)	8,239			(2		)	(19		)	—			8,218
	Income (loss) before income taxes	$	(34,008	)	$	9,608		$	9,289		$	(10,306	)	$	(25,417	)
	Three months ended March 31, 2014:
	Revenues from external customers	$	331,847		$	15,827		$	1,845		$	—		$	349,519
	Inter-segment revenues	—			36,579			7,508			(44,087		)	—
	Total revenues	331,847			52,406			9,353			(44,087		)	349,519
	Operating income	322,945			13,452			4,632			(11,949		)	329,080
	Other income (expense)	(57,660		)	52			—			—			(57,608		)
	Income before income taxes	$	265,285		$	13,504		$	4,632		$	(11,949	)	$	271,472
	As of March 31, 2015:
	Property, plant and equipment, net	$	5,194,649		$	56,270		$	207,713		$	(129,270	)	$	5,329,362
	Total assets	5,758,513			330,239			265,627			(437,442		)	5,916,937
	As of December 31, 2014:
	Property, plant and equipment, net	$	5,074,588		$	58,767		$	172,394		$	(118,963	)	$	5,186,786
	Total assets	5,802,295			281,844			212,685			(358,412		)	5,938,412

Condensed_Consolidating_Financ1

Condensed Consolidating Financial Information (Tables)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Condensed Consolidating Balance Sheet	Condensed Consolidating Balance Sheet
		31-Mar-15
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
		(In thousands)
	ASSETS
	Cash and cash equivalents	$	774		$	9,414		$	—		$	10,188
	Accounts receivable	—			243,169			—			243,169
	Accounts receivable – affiliates	1,032			143,517			(144,549		)	—
	Other current assets	148			293,082			—			293,230
	Oil and gas properties (successful efforts method)	—			6,187,638			—			6,187,638
	Other property and equipment	—			356,940			—			356,940
	Accumulated depreciation, depletion, amortization and impairment	—			(1,215,216		)	—			(1,215,216		)
	Investments in and advances to subsidiaries	4,499,571			—			(4,499,571		)	—
	Other long-term assets	190,812			12,674			(162,498		)	40,988
	Total assets	$	4,692,337		$	6,031,218		$	(4,806,618	)	$	5,916,937
	LIABILITIES AND EQUITY
	Accounts payable	$	—		$	9,339		$	—		$	9,339
	Accounts payable – affiliates	143,517			1,032			(144,549		)	—
	Other current liabilities	24,575			608,325			—			632,900
	Long-term debt	2,200,000			165,000			—			2,365,000
	Other long-term liabilities	—			747,951			(162,498		)	585,453
	Common stock	1,372			—			—			1,372
	Other equity	2,322,873			4,499,571			(4,499,571		)	2,322,873
	Total liabilities and equity	$	4,692,337		$	6,031,218		$	(4,806,618	)	$	5,916,937
	Condensed Consolidating Balance Sheet
		31-Dec-14
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
		(In thousands)
	ASSETS
	Cash and cash equivalents	$	776		$	45,035		$	—		$	45,811
	Accounts receivable	—			306,471			—			306,471
	Accounts receivable – affiliates	781			91,459			(92,240		)	—
	Prepaid expenses	297			13,976			—			14,273
	Other current assets	—			330,052			—			330,052
	Oil and gas properties (successful efforts method)	—			5,966,140			—			5,966,140
	Other property and equipment	—			313,439			—			313,439
	Accumulated depreciation, depletion, amortization and impairment	—			(1,092,793		)	—			(1,092,793		)
	Investments in and advances to subsidiaries	4,032,494			—			(4,032,494		)	—
	Other long-term assets	178,752			25,584			(149,317		)	55,019
	Total assets	$	4,213,100		$	5,999,363		$	(4,274,051	)	$	5,938,412
	LIABILITIES AND EQUITY
	Accounts payable	$	—		$	20,958		$	—		$	20,958
	Accounts payable – affiliates	91,459			781			(92,240		)	—
	Other current liabilities	49,340			724,830			—			774,170
	Long-term debt	2,200,000			500,000			—			2,700,000
	Other long-term liabilities	—			720,300			(149,317		)	570,983
	Equity	1,872,301			4,032,494			(4,032,494		)	1,872,301
	Total liabilities and equity	$	4,213,100		$	5,999,363		$	(4,274,051	)	$	5,938,412
Condensed Consolidating Statement of Operations	Condensed Consolidating Statement of Operations
		Three Months Ended March 31, 2015
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
		(In thousands)
	Total revenues	$	—		$	180,387		$	—		$	180,387
	Total operating expenses	8,619			205,403			—			214,022
	Operating loss	(8,619		)	(25,016		)	—			(33,635		)
	Equity in earnings in subsidiaries	12,619			—			(12,619		)	—
	Other income (expense)	(35,222		)	43,440			—			8,218
	Income (loss) before income taxes	(31,222		)	18,424			(12,619		)	(25,417		)
	Income tax benefit (expense)	13,181			(5,805		)	—			7,376
	Net income (loss)	$	(18,041	)	$	12,619		$	(12,619	)	$	(18,041	)
	Condensed Consolidating Statement of Operations
		Three Months Ended March 31, 2014
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
		(In thousands)
	Total revenues	$	—		$	349,519		$	—		$	349,519
	General and administrative expenses	5,612			17,908			—			23,520
	Other operating expenses	—			180,312			—			180,312
	Gain on sale of properties	—			183,393			—			183,393
	Operating income (loss)	(5,612		)	334,692			—			329,080
	Equity in earnings in subsidiaries	196,933			—			(196,933		)	—
	Interest expense, net of capitalized interest	(37,424		)	(2,734		)	—			(40,158		)
	Other income (expense)	3			(17,453		)	—			(17,450		)
	Income before income taxes	153,900			314,505			(196,933		)	271,472
	Income tax benefit (expense)	16,053			(117,572		)	—			(101,519		)
	Net income	$	169,953		$	196,933		$	(196,933	)	$	169,953
Condensed Consolidating Statement of Cash Flows	Condensed Consolidating Statement of Cash Flows
		Three Months Ended March 31, 2015
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
		(In thousands)
	Net cash provided by (used in) operating activities	$	(7,988	)	$	96,349		$	—		$	88,361
	Cash flows from investing activities:
	Capital expenditures	—			(359,113		)	—			(359,113		)
	Derivative settlements	—			109,259			—			109,259
	Other investing activities	—			(828		)	—			(828		)
	Net cash used in investing activities	—			(250,682		)	—			(250,682		)
	Cash flows from financing activities:
	Proceeds from sale of common stock	463,218			—			—			463,218
	Proceeds from revolving credit facility	—			145,000			—			145,000
	Principal payments on revolving credit facility	—			(480,000		)	—			(480,000		)
	Other financing activities	(455,232		)	453,712			—			(1,520		)
	Net cash provided by financing activities	7,986			118,712			—			126,698
	Decrease in cash and cash equivalents	(2		)	(35,621		)	—			(35,623		)
	Cash and cash equivalents at beginning of period	776			45,035			—			45,811
	Cash and cash equivalents at end of period	$	774		$	9,414		$	—		$	10,188
	Condensed Consolidating Statement of Cash Flows
		Three Months Ended March 31, 2014
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
		(In thousands)
	Net cash provided by (used in) operating activities	$	(56,630	)	$	264,897		$	—		$	208,267
	Cash flows from investing activities:
	Capital expenditures	—			(280,895		)	—			(280,895		)
	Proceeds from sale of properties	—			321,943			—			321,943
	Other investing activities	—			(6,147		)	—			(6,147		)
	Net cash provided by investing activities	—			34,901			—			34,901
	Cash flows from financing activities:
	Principal payments on revolving credit facility	—			(275,570		)	—			(275,570		)
	Other financing activities	23,289			(26,490		)	—			(3,201		)
	Net cash provided by (used in) financing activities	23,289			(302,060		)	—			(278,771		)
	Decrease in cash and cash equivalents	(33,341		)	(2,262		)	—			(35,603		)
	Cash and cash equivalents at beginning of period	34,277			57,624			—			91,901
	Cash and cash equivalents at end of period	$	936		$	55,362		$	—		$	56,298

Inventory_Schedule_of_Inventor

Inventory - Schedule of Inventory (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]
Equipment and materials	$14,219	$14,225
Crude oil inventory	7,737	7,129
Total inventory	$21,956	$21,354

Property_Plant_and_Equipment_S

Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Detail) (USD $)	Mar. 31, 2015		Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Proved oil and gas properties	$5,467,976,000	[1]	$5,156,875,000	[1]
Less: Accumulated depreciation, depletion, amortization and impairment	-1,157,925,000		-1,043,121,000
Proved oil and gas properties, net	4,310,051,000		4,113,754,000
Unproved oil and gas properties	719,662,000		809,265,000
Total oil and gas properties, net	5,029,713,000		4,923,019,000
Other property and equipment	356,940,000		313,439,000
Less: Accumulated depreciation	-57,291,000		-49,672,000
Other property and equipment, net	299,649,000		263,767,000
Total property, plant and equipment, net	5,329,362,000		5,186,786,000
Asset retirement costs	$37,500,000		$36,900,000
[1]	Included in the Company’s proved oil and gas properties are estimates of future asset retirement costs of $37.5 million and $36.9 million at March 31, 2015 and December 31, 2014, respectively.

Property_Plant_and_Equipment_A

Property, Plant and Equipment - Additional Information (Detail) (USD $)	3 Months Ended		0 Months Ended	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 05, 2014	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Impairment of oil and gas properties	$5,321,000	$762,000
Gain on sale of properties	0	183,393,000
Unproved property leases [Member]
Property, Plant and Equipment [Line Items]
Impairment of oil and gas properties	5,300,000	800,000
Non-Operated Oil and Natural Gas Properties [Member]
Property, Plant and Equipment [Line Items]
Proceeds from sale of properties			324,900,000
Gain on sale of properties				$187,000,000

Fair_Value_Measurements_Hierar

Fair Value Measurements - Hierarchy of Fair Value, Assets and Liabilities Measured on Recurring Basis (Detail) (Fair Value, Measurements, Recurring [Member], USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Assets:
Total assets	$254,062	$316,249
Money market funds [Member]
Assets:
Total assets	742	742
Commodity derivative instruments [Member]
Assets:
Total assets	253,320	315,507
Level 1 [Member]
Assets:
Total assets	742	742
Level 1 [Member] | Money market funds [Member]
Assets:
Total assets	742	742
Level 2 [Member]
Assets:
Total assets	253,320	315,507
Level 2 [Member] | Commodity derivative instruments [Member]
Assets:
Total assets	253,320	315,507
Level 3 [Member]
Assets:
Total assets	0	0
Level 3 [Member] | Money market funds [Member]
Assets:
Total assets	0	0
Level 3 [Member] | Commodity derivative instruments [Member]
Assets:
Total assets	$0	$0

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Derivative credit risk valuation adjustment, derivative assets	$400,000	$600,000
Long-term debt	2,365,000,000	2,700,000,000
Asset retirement obligation, carrying value	43,658,000	42,549,000
Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Long-term debt	2,200,000,000
Long-term debt, fair value	2,141,000,000
Second Amended Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, amount outstanding	$165,000,000

Derivative_Instruments_Schedul

Derivative Instruments - Schedule of Outstanding Commodity Derivative Instruments (Detail) (USD $)	Mar. 31, 2015
In Thousands, unless otherwise specified
Derivative [Line Items]
Fair Value Asset (Liability)	$253,320
2015 Two-Way Collars [Member]
Derivative [Line Items]
Total Notional Amount of Oil (Barrels)	1,402
Average Floor Price (in dollars per barrel)	86.52
Average Ceiling Price (in dollars per barrel)	102.86
Fair Value Asset (Liability)	57,100
2015 Swaps [Member]
Derivative [Line Items]
Total Notional Amount of Oil (Barrels)	3,381
Average Swap Price (in dollars per barrel)	89.36
Fair Value Asset (Liability)	152,359
2015 Deferred Premium Puts [Member]
Derivative [Line Items]
Total Notional Amount of Oil (Barrels)	546
Average Floor Price (in dollars per barrel)	90
Average deferred premium (in dollars per barrel)	2.55
Fair Value Asset (Liability)	28,188
2016 Two Way Collars [Member]
Derivative [Line Items]
Total Notional Amount of Oil (Barrels)	155
Average Floor Price (in dollars per barrel)	86
Average Ceiling Price (in dollars per barrel)	103.42
Fair Value Asset (Liability)	4,717
2016 Swaps [Member]
Derivative [Line Items]
Total Notional Amount of Oil (Barrels)	372
Average Swap Price (in dollars per barrel)	85.27
Fair Value Asset (Liability)	$10,956

Derivative_Instruments_Schedul1

Derivative Instruments - Schedule of Location and Fair Value of Outstanding Commodity Derivative Instruments (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]
Derivative instruments — current assets	$253,320	$302,159
Derivative instruments — non-current assets	0	13,348
Total derivative instruments	253,320
Crude oil [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments — current assets	253,320	302,159
Derivative instruments — non-current assets	0	13,348
Total derivative instruments	$253,320	$315,507

Derivative_Instruments_Realize

Derivative Instruments - Realized and Unrealized Gains and Losses from Commodity Derivative Instruments (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Net gain (loss) on derivative instruments	$47,072	($17,603)

Derivative_Instruments_Summary

Derivative Instruments - Summary of Gross and Net Information about Commodity Derivative Instruments (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amounts of Recognized Assets	$268,107	$331,121
Derivative Assets, Gross Amounts Offset in the Balance Sheet	-14,787	-15,614
Net Amounts of Assets Presented in the Balance Sheet	253,320	315,507
Gross Amounts of Recognized Liabilities	14,787	15,614
Derivative Liabilities, Gross Amounts Offset in the Balance Sheet	-14,787	-15,614
Net Amounts of Liabilities Presented in the Balance Sheet	$0	$0

LongTerm_Debt_LongTerm_Debt_Ad

Long-Term Debt Long-Term Debt - Additional Information (Details) (USD $)	3 Months Ended		24 Months Ended	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2014
Debt Instrument [Line Items]
Deferred financing costs	$33,900,000
Amortization of deferred financing costs	1,600,000	1,600,000
Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Net proceeds from issuance of notes			1,175,800,000
Redemption percentage, maximum	35.00%
Redemption term	180 days
Percentage of minimum outstanding principal amount	65.00%
Event of default by payment default ($10.0 million or more)	10,000,000
Event of default by final judgments (in excess of $10.0 million)	10,000,000
Second Amended Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility maximum increase to aggregate commitments	2,000,000,000
Line of credit facility, maximum borrowing capacity	1,500,000,000
Line of credit facility, capacity available for specific purpose other than for trade purchases	2,500,000,000
Commitment fee of borrowing base capacity not utilized	0.38%
Minimum current ratio	1
Line of credit facility, amount outstanding	165,000,000
Outstanding letters of credit	5,200,000
Line of credit facility, remaining borrowing capacity	1,329,800,000
Weighted average interest rate	1.70%				1.90%
Minimum [Member] | Second Amended Credit Facility [Member]
Debt Instrument [Line Items]
Percentage of the reserve value of assets as determined by reserve reports (at least 80%)	80.00%
Ratio of EBITDAX to interest expense necessary to maintain covenants	2.5
2022 Notes [Member] | Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Principal debt amount				1,000,000,000
Stated interest rate				6.88%
Net proceeds from issuance of notes				983,600,000
2019 Notes [Member] | Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Principal debt amount			400,000,000
Stated interest rate			7.25%
2021 Notes [Member] | Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Principal debt amount			400,000,000
Stated interest rate			6.50%
2023 Notes [Member] | Senior Unsecured Debt [Member]
Debt Instrument [Line Items]
Principal debt amount			$400,000,000
Stated interest rate			6.88%

LongTerm_Debt_Schedule_of_Long

Long-Term Debt - Schedule of Long-Term Debt Interest Rate (Detail)	3 Months Ended
	Mar. 31, 2015
Less than .25 to 1 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.25
Less than .25 to 1 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	1.50%
Less than .25 to 1 [Member] | ABR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	0.00%
Greater than or equal to .25 to 1 but less than .50 to 1 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.5
Greater than or equal to .25 to 1 but less than .50 to 1 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.25
Greater than or equal to .25 to 1 but less than .50 to 1 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	1.75%
Greater than or equal to .25 to 1 but less than .50 to 1 [Member] | ABR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	0.25%
Greater than or equal to .50 to 1 but less than .75 to 1 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.75
Greater than or equal to .50 to 1 but less than .75 to 1 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.5
Greater than or equal to .50 to 1 but less than .75 to 1 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	2.00%
Greater than or equal to .50 to 1 but less than .75 to 1 [Member] | ABR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	0.50%
Greater than or equal to .75 to 1 but less than .90 to 1 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.9
Greater than or equal to .75 to 1 but less than .90 to 1 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.75
Greater than or equal to .75 to 1 but less than .90 to 1 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	2.25%
Greater than or equal to .75 to 1 but less than .90 to 1 [Member] | ABR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	0.75%
Greater than .90 to 1 but less than or equal 1 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Outstanding Borrowings to Borrowing Base	0.9
Greater than .90 to 1 but less than or equal 1 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	2.50%
Greater than .90 to 1 but less than or equal 1 [Member] | ABR [Member]
Debt Instrument [Line Items]
Debt instrument interest rate terms, in percentage	1.00%

Asset_Retirement_Obligations_S

Asset Retirement Obligations - Schedule of Changes in Asset Retirement Obligations (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Balance at December 31, 2014	$42,549
Liabilities incurred during period	372
Liabilities settled during period	-41
Accretion expense during period	537	[1]
Revisions to estimates	241
Balance at March 31, 2015	$43,658
[1]	Included in depreciation, depletion and amortization on the Company’s Condensed Consolidated Statement of Operations.

Asset_Retirement_Obligations_A

Asset Retirement Obligations - Additional Information (Detail) (USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
Asset Retirement Obligation Disclosure [Abstract]
Total asset retirement obligations, current portion	$0.70

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Income tax benefit	$7,376,000	($101,519,000)
Effective tax rate	29.00%	37.40%
Income Tax Benefit, Excluding Discrete Tax Items	$10,600,000
Income Tax Benefit, Excluding Discrete Tax Items, Percentage of Loss Before Tax	41.60%

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$7,606	$4,505
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Restricted stock granted	1,219,820
Granted, weighted average grant date fair value per unit	$13.09
Stock-based compensation expense	6,800	3,900
Restricted Stock [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual forfeiture rate	0.00%
Restricted Stock [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual forfeiture rate	16.90%
Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted	425,590
Granted, weighted average grant date fair value per unit	$11.20
Stock-based compensation expense	$800	$600
Right to received shares of common stock	1
Performance share units initial performance period, years	3 years
Grant date fair value amortization term	4 years
Number of trading days	30 days
Performance Share Units [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual forfeiture rate	2.40%
PSU granted percentage of earnings	0.00%
Performance Share Units [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual forfeiture rate	4.90%
PSU granted percentage of earnings	200.00%
PSU 2015 Grants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant date fair value amortization term	4 years
Expected percentage earned	86.00%

StockBased_Compensation_Summar

Stock-Based Compensation - Summary of Assumptions (Detail) (PSU 2015 Grants [Member])	3 Months Ended
	Mar. 31, 2015
PSU 2015 Grants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Forecast period (years)	4 years
Risk-free interest rate	0.99%
Oasis stock price volatility	50.11%

Common_Stock_Details

Common Stock (Details) (USD $)	0 Months Ended	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 09, 2015	Mar. 31, 2015	Mar. 31, 2014	Mar. 09, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Common stock, par value (in dollars per share)		$0.01			$0.01
Shares issued, price per share	$12.80			$12.80
Proceeds from sale of common stock	$463,100	$463,218	$0
Common Stock [Member]
Class of Stock [Line Items]
Issuance of common stock, shares	36,800,000
Additional Paid-in-Capital [Member]
Class of Stock [Line Items]
Proceeds from sale of common stock	462,700
Common Stock [Member]
Class of Stock [Line Items]
Issuance of common stock, shares		36,800,000
Proceeds from sale of common stock	$368
Over-Allotment Option [Member] | Common Stock [Member]
Class of Stock [Line Items]
Issuance of common stock, shares	4,800,000

Earnings_Per_Share_Schedule_of

Earnings Per Share - Schedule of Weighted-Average Number of Shares Outstanding (Detail)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Earnings Per Share [Abstract]
Basic weighted average common shares outstanding	109,303		99,560
Dilution effect of stock awards at end of period(1)	0	[1]	489	[1]
Diluted weighted average common shares outstanding	109,303		100,049
Anti-dilutive stock-based compensation awards	3,046		1,047
[1]	No unvested stock awards were included in computing loss per share for the three months ended March 31, 2015 because the effect was anti-dilutive.

Business_Segment_Information_A

Business Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2015
	Segment
Segment Reporting [Abstract]
Current operating units	3

Business_Segment_Information_S

Business Segment Information - Summarized Financial Information of Segments (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Total revenues	$180,387	$349,519
Operating income (loss)	-33,635	329,080
Other income (expense)	8,218	-57,608
Income (loss) before income taxes	-25,417	271,472
Property, Plant and Equipment, Net	5,329,362		5,186,786
Total assets	5,916,937		5,938,412
Exploration and Production [Member]
Segment Reporting Information [Line Items]
Total revenues	173,859	331,847
Well Services [Member]
Segment Reporting Information [Line Items]
Total revenues	50,905	52,406
Midstream Services [Member]
Segment Reporting Information [Line Items]
Total revenues	17,642	9,353
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	180,387	349,519
Operating income (loss)	-33,635	329,080
Other income (expense)	8,218	-57,608
Income (loss) before income taxes	-25,417	271,472
Property, Plant and Equipment, Net	5,329,362		5,186,786
Total assets	5,916,937		5,938,412
Operating Segments [Member] | Exploration and Production [Member]
Segment Reporting Information [Line Items]
Total revenues	173,859	331,847
Operating income (loss)	-42,247	322,945
Other income (expense)	8,239	-57,660
Income (loss) before income taxes	-34,008	265,285
Property, Plant and Equipment, Net	5,194,649		5,074,588
Total assets	5,758,513		5,802,295
Operating Segments [Member] | Well Services [Member]
Segment Reporting Information [Line Items]
Total revenues	2,708	15,827
Operating income (loss)	9,610	13,452
Other income (expense)	-2	52
Income (loss) before income taxes	9,608	13,504
Property, Plant and Equipment, Net	56,270		58,767
Total assets	330,239		281,844
Operating Segments [Member] | Midstream Services [Member]
Segment Reporting Information [Line Items]
Total revenues	3,820	1,845
Operating income (loss)	9,308	4,632
Other income (expense)	-19
Income (loss) before income taxes	9,289	4,632
Property, Plant and Equipment, Net	207,713		172,394
Total assets	265,627		212,685
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Total revenues	-62,019	-44,087
Operating income (loss)	-10,306	-11,949
Income (loss) before income taxes	-10,306	-11,949
Property, Plant and Equipment, Net	-129,270		-118,963
Total assets	-437,442		-358,412
Segment Reconciling Items [Member] | Well Services [Member]
Segment Reporting Information [Line Items]
Total revenues	48,197	36,579
Segment Reconciling Items [Member] | Midstream Services [Member]
Segment Reporting Information [Line Items]
Total revenues	$13,822	$7,508

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Commitments And Contingencies [Line Items]
Total rental commitments under leases	$32,500,000
Rig termination	1,080,000	0
Future obligations under purchase agreements	52,800,000
Future obligations under cost sharing agreements	8,100,000
Long Term Commitments [Member]
Commitments And Contingencies [Line Items]
Future obligations under supply agreements	190,500,000
Drilling contracts [Member]
Commitments And Contingencies [Line Items]
Rig termination	1,100,000
Payments upon early contract termination	$10,200,000
Williston Basin Project [Member] | Long Term Commitments [Member]
Commitments And Contingencies [Line Items]
Maximum commitment term	10 years
Williston Basin Project [Member] | Long Term Commitments [Member] | Crude oil [Member]
Commitments And Contingencies [Line Items]
Minimum quantity of delivery	31,000
Williston Basin Project [Member] | Long Term Commitments [Member] | Natural Gas [Member]
Commitments And Contingencies [Line Items]
Minimum quantity of delivery	6,600

Condensed_Consolidating_Financ2

Condensed Consolidating Financial Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Ownership percentage, Guarantors	100.00%

Condensed_Consolidating_Financ3

Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Balance Sheet (Detail) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
ASSETS
Cash and cash equivalents	$10,188	$45,811	$56,298	$91,901
Accounts receivable	243,169	306,471
Prepaid expenses	16,954	14,273
Other current assets	293,230	330,052
Oil and gas properties (successful efforts method)	6,187,638	5,966,140
Other property and equipment	356,940	313,439
Less: accumulated depreciation, depletion, amortization and impairment	-1,215,216	-1,092,793
Other long-term assets	40,988	55,019
Total assets	5,916,937	5,938,412
LIABILITIES AND STOCKHOLDERS’ EQUITY
Accounts payable	9,339	20,958
Other current liabilities	632,900	774,170
Long-term debt	2,365,000	2,700,000
Other long-term liabilities	585,453	570,983
Common stock	1,372	1,001
Other equity	2,322,873
Equity	2,324,245	1,872,301
Total liabilities and stockholders’ equity	5,916,937	5,938,412
Parent/Issuer [Member]
ASSETS
Cash and cash equivalents	774	776	936	34,277
Accounts receivable – affiliates	1,032	781
Prepaid expenses		297
Other current assets	148
Investments in and advances to subsidiaries	4,499,571	4,032,494
Other long-term assets	190,812	178,752
Total assets	4,692,337	4,213,100
LIABILITIES AND STOCKHOLDERS’ EQUITY
Accounts payable – affiliates	143,517	91,459
Other current liabilities	24,575	49,340
Long-term debt	2,200,000	2,200,000
Common stock	1,372
Other equity	2,322,873
Equity		1,872,301
Total liabilities and stockholders’ equity	4,692,337	4,213,100
Combined Guarantor Subsidiaries [Member]
ASSETS
Cash and cash equivalents	9,414	45,035	55,362	57,624
Accounts receivable	243,169	306,471
Accounts receivable – affiliates	143,517	91,459
Prepaid expenses		13,976
Other current assets	293,082	330,052
Oil and gas properties (successful efforts method)	6,187,638	5,966,140
Other property and equipment	356,940	313,439
Less: accumulated depreciation, depletion, amortization and impairment	-1,215,216	-1,092,793
Other long-term assets	12,674	25,584
Total assets	6,031,218	5,999,363
LIABILITIES AND STOCKHOLDERS’ EQUITY
Accounts payable	9,339	20,958
Accounts payable – affiliates	1,032	781
Other current liabilities	608,325	724,830
Long-term debt	165,000	500,000
Other long-term liabilities	747,951	720,300
Other equity	4,499,571
Equity		4,032,494
Total liabilities and stockholders’ equity	6,031,218	5,999,363
Intercompany Eliminations [Member]
ASSETS
Accounts receivable – affiliates	-144,549	-92,240
Investments in and advances to subsidiaries	-4,499,571	-4,032,494
Other long-term assets	-162,498	-149,317
Total assets	-4,806,618	-4,274,051
LIABILITIES AND STOCKHOLDERS’ EQUITY
Accounts payable – affiliates	-144,549	-92,240
Other long-term liabilities	-162,498	-149,317
Other equity	-4,499,571
Equity		-4,032,494
Total liabilities and stockholders’ equity	($4,806,618)	($4,274,051)

Condensed_Consolidating_Financ4

Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Statement of Operations (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Revenues
Total revenues	$180,387	$349,519
Expenses
General and administrative expenses	23,324	23,520
Other operating expenses		180,312
Total expenses	214,022	203,832
Gain on sale of properties	0	183,393
Operating income (loss)	-33,635	329,080
Other income (expense)
Interest expense, net of capitalized interest	-38,784	-40,158
Other income (expense)	8,218	-17,450
Income (loss) before income taxes	-25,417	271,472
Income tax benefit (expense)	7,376	-101,519
Net income (loss)	-18,041	169,953
Parent/Issuer [Member]
Expenses
General and administrative expenses		5,612
Total expenses	8,619
Operating income (loss)	-8,619	-5,612
Other income (expense)
Equity in earnings in subsidiaries	12,619	196,933
Interest expense, net of capitalized interest		-37,424
Other income (expense)	-35,222	3
Income (loss) before income taxes	-31,222	153,900
Income tax benefit (expense)	13,181	16,053
Net income (loss)	-18,041	169,953
Combined Guarantor Subsidiaries [Member]
Revenues
Total revenues	180,387	349,519
Expenses
General and administrative expenses		17,908
Other operating expenses		180,312
Total expenses	205,403
Gain on sale of properties		183,393
Operating income (loss)	-25,016	334,692
Other income (expense)
Interest expense, net of capitalized interest		-2,734
Other income (expense)	43,440	-17,453
Income (loss) before income taxes	18,424	314,505
Income tax benefit (expense)	-5,805	-117,572
Net income (loss)	12,619	196,933
Intercompany Eliminations [Member]
Other income (expense)
Equity in earnings in subsidiaries	-12,619	-196,933
Income (loss) before income taxes	-12,619	-196,933
Net income (loss)	($12,619)	($196,933)

Condensed_Consolidating_Financ5

Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Statement of Cash Flows (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net cash provided by operating activities	$88,361	$208,267
Cash flows from investing activities:
Capital expenditures	-359,113	-280,895
Proceeds from sale of properties	0	321,943
Derivative settlements	109,259	-2,239
Other investing activities	-828	-6,147
Net cash provided by (used in) investing activities	-250,682	34,901
Cash flows from financing activities:
Proceeds from sale of common stock	463,218	0
Proceeds from revolving credit facility	145,000	0
Principal payments on revolving credit facility	-480,000	-275,570
Other financing activities	-1,520	-3,201
Net cash provided by (used in) financing activities	126,698	-278,771
Decrease in cash and cash equivalents	-35,623	-35,603
Beginning of period	45,811	91,901
End of period	10,188	56,298
Parent/Issuer [Member]
Cash flows from operating activities:
Net cash provided by operating activities	-7,988	-56,630
Cash flows from investing activities:
Net cash provided by (used in) investing activities	0
Cash flows from financing activities:
Proceeds from sale of common stock	463,218
Other financing activities	-455,232	23,289
Net cash provided by (used in) financing activities	7,986	23,289
Decrease in cash and cash equivalents	-2	-33,341
Beginning of period	776	34,277
End of period	774	936
Combined Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash provided by operating activities	96,349	264,897
Cash flows from investing activities:
Capital expenditures	-359,113	-280,895
Proceeds from sale of properties		321,943
Derivative settlements	109,259
Other investing activities	-828	-6,147
Net cash provided by (used in) investing activities	-250,682	34,901
Cash flows from financing activities:
Proceeds from revolving credit facility	145,000
Principal payments on revolving credit facility	-480,000	-275,570
Other financing activities	453,712	-26,490
Net cash provided by (used in) financing activities	118,712	-302,060
Decrease in cash and cash equivalents	-35,621	-2,262
Beginning of period	45,035	57,624
End of period	$9,414	$55,362

Subsequent_Events_Subsequent_E

Subsequent Events Subsequent Events (Details) (USD $)	Mar. 31, 2015	Apr. 13, 2015	Apr. 12, 2015	7-May-15
	financial_institution
Subsequent Event [Line Items]
Number of lenders in the bank group	18
Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Line of credit facility maximum increase to aggregate commitments	2,000,000,000
Line of credit facility, maximum borrowing capacity	1,500,000,000
Revolving Credit Facility [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Line of credit facility maximum increase to aggregate commitments		1,700,000,000	2,000,000,000
Line of credit facility, maximum borrowing capacity		$1,525,000,000	$1,500,000,000
Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Average swap price (in dollars per barrel)				61.28
Two Thousand Fifteen Swap Agreement [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Total Notional Amount of Oil (Barrels)				1,102
Two Thousand Sixteen Swap Agreement [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Total Notional Amount of Oil (Barrels)				703
Two Thousand Seventeen Swap Agreement [Member] | Not Designated as Hedging Instrument [Member] | Energy Related Derivative [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Total Notional Amount of Oil (Barrels)				31