Chord Energy (CHRD) 10-Q 7 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	5-May-14
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Trading Symbol	'OAS	'
Entity Registrant Name	'Oasis Petroleum Inc.	'
Entity Central Index Key	'0001486159	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	101,174,985

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheet (Unaudited) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
ASSETS	'	'
Cash and cash equivalents	$56,298	$91,901
Accounts receivable — oil and gas revenues	202,749	175,653
Accounts receivable — joint interest partners	134,553	139,459
Inventory	19,862	20,652
Prepaid expenses	24,450	10,191
Deferred income taxes	8,484	6,335
Derivative instruments	778	2,264
Advances to joint interest partners	214	760
Other current assets	420	391
Total current assets	447,808	447,606
Property, plant and equipment	'	'
Oil and gas properties (successful efforts method)	4,820,902	4,528,958
Other property and equipment	200,158	188,468
Less: accumulated depreciation, depletion, amortization and impairment	-723,429	-637,676
Total property, plant and equipment, net	4,297,631	4,079,750
Assets held for sale	0	137,066
Derivative instruments	470	1,333
Deferred costs and other assets	46,175	46,169
Total assets	4,792,084	4,711,924
LIABILITIES AND STOCKHOLDERS’ EQUITY	'	'
Accounts payable	24,516	8,920
Advances from joint interest partners	10,931	12,829
Revenues and production taxes payable	183,120	146,741
Accrued liabilities	283,024	241,830
Accrued interest payable	24,562	47,910
Derivative instruments	20,663	8,188
Other current liabilities	2,766	0
Total current liabilities	549,582	466,418
Long-term debt	2,260,000	2,535,570
Asset retirement obligations	35,790	35,918
Derivative instruments	679	139
Deferred income taxes	424,049	323,147
Other liabilities	2,002	2,183
Total liabilities	3,272,102	3,363,375
Commitments and contingencies (Note 14)	'	'
Stockholders’ equity	'	'
Common stock, $0.01 par value: 300,000,000 shares authorized; 101,416,749 and 100,866,589 shares issued at March 31, 2014 and December 31, 2013, respectively	999	996
Treasury stock, at cost: 238,453 and 167,155 shares at March 31, 2014 and December 31, 2013, respectively	-8,387	-5,362
Additional paid-in capital	989,525	985,023
Retained earnings	537,845	367,892
Total stockholders’ equity	1,519,982	1,348,549
Total liabilities and stockholders’ equity	$4,792,084	$4,711,924

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheet (Unaudited) (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
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	101,416,749	100,866,589
Treasury stock, shares	238,453	167,155

Condensed_Consolidated_Stateme

Condensed Consolidated Statement of Operations (Unaudited) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Revenues	'	'
Oil and gas revenues	$331,847	$241,651
Well services and midstream revenues	17,672	6,653
Total revenues	349,519	248,304
Expenses	'	'
Lease operating expenses	39,989	19,489
Well services and midstream operating expenses	10,920	2,914
Marketing, transportation and gathering expenses	5,186	3,389
Production taxes	31,803	22,089
Depreciation, depletion and amortization	91,272	66,261
Exploration expenses	380	1,857
Impairment of oil and gas properties	762	498
General and administrative expenses	23,520	13,854
Total expenses	203,832	130,351
Gain on sale of properties	183,393	0
Operating income (loss)	329,080	117,953
Other income (expense)	'	'
Net loss on derivative instruments	-17,603	-14,612
Interest expense, net of capitalized interest	-40,158	-21,183
Other income (expense)	153	780
Total other income (expense)	-57,608	-35,015
Income before income taxes	271,472	82,938
Income tax expense	101,519	31,087
Net income	$169,953	$51,851
Earnings per share:	'	'
Basic (in dollars per share)	$1.71	$0.56
Diluted (in dollars per share)	$1.70	$0.56
Weighted average shares outstanding:	'	'
Basic (in shares)	99,560	92,375
Diluted (in shares)	100,049	92,651

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, unless otherwise specified
Balance at Dec. 31, 2013	$1,348,549	$996	($5,362)	$985,023	$367,892
Balance, shares at Dec. 31, 2013	'	100,699	167	'	'
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'
Fees (2013 issuance of common stock)	-176	'	'	-176	'
Stock-based compensation	4,681	'	'	4,681	'
Stock-based compensation, shares	'	550	'	'	'
Vesting of restricted shares	'	3	'	-3	'
Treasury stock – tax withholdings	-3,025	'	-3,025	'	'
Treasury stock - tax withholdings, shares	'	-71	71	'	'
Net income	169,953	'	'	'	169,953
Balance at Mar. 31, 2014	$1,519,982	$999	($8,387)	$989,525	$537,845
Balance, shares at Mar. 31, 2014	'	101,178	238	'	'

Condensed_Consolidated_Stateme2

Condensed Consolidated Statement of Cash Flows (Unaudited) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:	'	'
Net income	$169,953	$51,851
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation, depletion and amortization	91,272	66,261
Gain on sale of properties	-183,393	0
Impairment of oil and gas properties	762	498
Deferred income taxes	98,753	30,987
Derivative instruments	17,603	14,612
Stock-based compensation expenses	4,505	2,289
Debt discount amortization and other	1,487	746
Working capital and other changes:	'	'
Change in accounts receivable	-9,275	-3,360
Change in inventory	790	-8,407
Change in prepaid expenses	-14,259	293
Change in other current assets	-29	-232
Change in other assets	-1,593	0
Change in accounts payable and accrued liabilities	29,007	15,009
Change in other current liabilities	2,766	0
Change in other liabilities	-82	0
Net cash provided by operating activities	208,267	170,547
Cash flows from investing activities:	'	'
Capital expenditures	-280,895	-217,819
Proceeds from sale of properties	321,943	0
Costs related to sale of properties	-2,010	0
Derivative settlements	-2,239	1,686
Advances from joint interest partners	-1,898	-1,691
Net cash provided by (used in) investing activities	34,901	-217,824
Cash flows from financing activities:	'	'
Principal payments on revolving credit facility	-275,570	0
Purchases of treasury stock	-3,025	-156
Debt issuance costs	0	-25
Other	-176	0
Net cash used in financing activities	-278,771	-181
Decrease in cash and cash equivalents	-35,603	-47,458
Cash and cash equivalents:	'	'
Beginning of period	91,901	213,447
End of period	56,298	165,989
Supplemental non-cash transactions:	'	'
Change in accrued capital expenditures	39,516	13,735
Change in asset retirement obligations	($128)	$2,048

Organization_and_Operations_of

Organization and Operations of the Company	3 Months Ended
	Mar. 31, 2014
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. In 2007, Oasis Petroleum North America LLC (“OPNA”), a Delaware limited liability company, was formed to conduct 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. As part of the formation of OMS, the Company transferred substantially all of its salt water disposal and other midstream assets from OPNA to OMS.
	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 a 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.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
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, 2013 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, 2013 (“2013 Annual Report”).
	Significant Accounting Policies
	There have been no material changes to the Company’s critical accounting policies and estimates from those disclosed in the 2013 Annual Report.

Inventory

Inventory	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Inventory	'
	Inventory
	Equipment and materials consist primarily of tubular goods, well equipment to be used in future drilling or repair operations, well fracturing equipment, chemicals and proppant, all of which are stated at the lower of cost or market value with cost determined on an average cost method. Crude oil inventory includes oil in tank and linefill and is stated at the lower of average cost or market value. Inventory consists of the following:
		March 31, 2014		December 31, 2013
		(In thousands)
	Equipment and materials	$	10,207	$	11,669
	Crude oil inventory	9,655		8,983
	Total inventory	$	19,862	$	20,652

Property_Plant_and_Equipment

Property, Plant and Equipment	3 Months Ended
	Mar. 31, 2014
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-14			31-Dec-13
		(In thousands)
	Proved oil and gas properties(1)	$	3,985,490		$	3,713,525
	Less: Accumulated depreciation, depletion, amortization and impairment	(693,011		)	(612,380		)
	Proved oil and gas properties, net	3,292,479			3,101,145
	Unproved oil and gas properties	835,412			815,433
	Total oil and gas properties, net	4,127,891			3,916,578
	Other property and equipment	200,158			188,468
	Less: Accumulated depreciation	(30,418		)	(25,296		)
	Other property and equipment, net	169,740			163,172
	Total property, plant and equipment, net	$	4,297,631		$	4,079,750
	__________________
	-1	Included in the Company’s proved oil and gas properties are estimates of future asset retirement costs of $32.1 million and $32.6 million at March 31, 2014 and December 31, 2013, respectively.
	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 $0.8 million and $0.5 million for the three months ended March 31, 2014 and 2013, respectively. No impairment charges on proved oil and natural gas properties were recorded for the three months ended March 31, 2014 or 2013.

Divestiture

Divestiture	3 Months Ended
	Mar. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Divestiture	'
	Divestiture
	On March 5, 2014, the Company completed the sale of certain non-operated properties in its Sanish project area and other non-operated leases adjacent to its Sanish position (the “Sanish Divestiture”) for cash proceeds of approximately $321.9 million, which includes, and is subject to further, customary post close adjustments. The Company recognized a $183.4 million gain on sale of properties in its Condensed Consolidated Statement of Operations for the three months ended March 31, 2014. The transaction was structured as an Internal Revenue Code Section 1031 like-kind exchange for tax purposes and as such did not give rise to any currently taxable gain.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	Fair Value Measurements
	In accordance with the Financial Accounting Standards Board’s (“FASB”) 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, 2014
		Level 1		Level 2		Level 3		Total
		(In thousands)
	Assets:
	Money market funds	$	742	$	—	$	—	$	742
	Commodity derivative instruments (see Note 7)	—		1,248		—		1,248
	Total assets	$	742	$	1,248	$	—	$	1,990
	Liabilities:
	Commodity derivative instruments (see Note 7)	$	—	$	21,342	$	—	$	21,342
	Total liabilities	$	—	$	21,342	$	—	$	21,342
		At fair value as of December 31, 2013
		Level 1		Level 2		Level 3		Total
		(In thousands)
	Assets:
	Money market funds	$	742	$	—	$	—	$	742
	Commodity derivative instruments (see Note 7)	—		3,597		—		3,597
	Total assets	$	742	$	3,597	$	—	$	4,339
	Liabilities:
	Commodity derivative instruments (see Note 7)	$	—	$	8,327	$	—	$	8,327
	Total liabilities	$	—	$	8,327	$	—	$	8,327
	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, 2014 and December 31, 2013. The Company’s money market funds represent cash equivalents backed by the assets of high-quality major banks and financial institutions. The Company identified 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 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 calculated 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 liability by $0.3 million and $0.2 million at March 31, 2014 and December 31, 2013, 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, 2014, 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, 2014 is $2,260.0 million, which includes $2,200.0 million of senior unsecured notes and $60.0 million of borrowings under the revolving credit facility (see Note 8 – Long-Term Debt). The fair value of the Company’s senior unsecured notes, which are Level 1 liabilities, is $2,374.5 million at March 31, 2014.
	Nonfinancial Assets and Liabilities
	Asset retirement obligations. The carrying amount of the Company’s ARO in the Condensed Consolidated Balance Sheet at March 31, 2014 is $36.3 million (see Note 9 – Asset Retirement Obligations). The Company determines the 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 timing and existence of a liability, as well as what constitutes adequate restoration. 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 oil and natural gas properties and compares such undiscounted future cash flows to the carrying amount of the 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, 2014 or 2013.

Derivative_Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2014
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, 2014, the Company utilized two-way and three-way costless collar options, swaps and swaps with sub-floors 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 three-way collar is a combination of options: a sold call, a purchased put and a sold put. The purchased put establishes a minimum price (floor), unless the market price falls below the sold put (sub-floor), at which point the minimum price would be NYMEX West Texas Intermediate (“WTI”) crude oil index price plus the difference between the purchased put and the sold put strike price. 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). A swap with a sub-floor is a swap coupled with a sold put (sub-floor) at which point the minimum price would be WTI crude oil index price plus the difference between the swap and the sold put strike price.
	All derivative instruments are recorded on the balance sheet as either assets or liabilities measured at fair value (see Note 6 – 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, both cash settlements and non-cash changes in fair value, are recognized in the other income (expense) section of the 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 are reflected as investing activities in the Company’s Condensed Consolidated Statement of Cash Flows.
	As of March 31, 2014, the Company had the following outstanding commodity derivative instruments, all of which settle monthly based on the average WTI crude oil index price:
	Settlement		Derivative		Total Notional			Weighted Average Prices										Fair Value
	Period		Instrument		Amount of Oil													Asset
								Swap				Sub-Floor		Floor		Ceiling		(Liability)
					(Barrels)			($/Barrel)										(In thousands)
	2014		Two-way collars		993,500									$	90	$	100.91	$	(1,433	)
	2014		Three-way collars		2,581,500							$	70.53	$	90.53	$	105.13	(339		)
	2014		Swaps		3,094,500			$	96.45									(7,101		)
	2014		Swaps with sub-floors		1,650,000			$	92.6			$	70					(9,636		)
	2015		Two-way collars		108,500									$	90	$	99.86	71
	2015		Three-way collars		263,500							$	70.59	$	90.59	$	105.25	458
	2015		Swaps		3,384,500			$	90.27									(2,164		)
	2015		Swaps with sub-floors		186,000			$	92.6			$	70					(349		)
	2016		Swaps		186,000			$	89.39									399
																		$	(20,094	)
	The following table summarizes the location and fair value of all outstanding commodity derivative instruments recorded in the balance sheet for the periods presented:
	Fair Value of Derivative Instrument Assets (Liabilities)
					Fair Value
	Commodity		Balance Sheet Location		March 31, 2014				31-Dec-13
					(In thousands)
	Crude oil		Derivative instruments — current assets		$	778			$	2,264
	Crude oil		Derivative instruments — non-current assets		470				1,333
	Crude oil		Derivative instruments — current liabilities		(20,663		)		(8,188		)
	Crude oil		Derivative instruments — non-current liabilities		(679		)		(139		)
	Total derivative instruments				$	(20,094	)		$	(4,730	)
	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		2014				2013
				(In thousands)
	Change in fair value of derivative instruments	Net loss on derivative instruments		$	(15,364	)		$	(16,298	)
	Derivative settlements	Net loss on derivative instruments		(2,239		)		1,686
	Total net loss on derivative instruments			$	(17,603	)		$	(14,612	)
	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, 2014		$	23,775			$	(22,527	)		$	1,248
	As of December 31, 2013		22,743				(19,146		)		3,597
	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, 2014		$	43,869			$	(22,527	)		$	21,342
	As of December 31, 2013		27,473				(19,146		)		8,327

LongTerm_Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Long-Term Debt	'
	Long-Term Debt
	Senior unsecured notes. On September 24, 2013, the Company issued $1,000.0 million of 6.875% senior unsecured notes due March 15, 2022 (the “2022 Notes”). The issuance of the 2022 Notes 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 in its West Williston project area.
	In connection with the issuance of the 2022 Notes, the Company along with its material subsidiaries (the “Guarantors”) entered into a Registration Rights Agreement pursuant to which the Company and Guarantors agreed to file a registration statement with the SEC to allow the holders of the 2022 Notes to exchange the 2022 Notes for the same principal amount of a new issue of notes with substantially identical terms, except the new notes will be freely transferable under the Securities Act. The Company and the Guarantors will use commercially reasonable efforts to cause the exchange to be completed within 360 days after the 2022 Notes issuance date. Under certain circumstances, in lieu of a registered exchange offer, the Company must use commercially reasonable efforts to file a shelf registration statement for the resale of the 2022 Notes. If the Company fails to satisfy these obligations on a timely basis, the annual interest borne by the 2022 Notes will be increased by 1.0% per annum until the exchange offer is completed or the shelf registration statement is declared effective. The Company estimates the value of this contingent interest is immaterial at March 31, 2014 and December 31, 2013.
	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,” and together with the 2022 Notes, 2019 Notes and 2021 Notes, the “Notes”). The issuance of the 2019 Notes, 2021 Notes and the 2023 Notes resulted in aggregate net proceeds to the Company of $1,175.8 million. The Company used the proceeds from the 2019 Notes, 2021 Notes and the 2023 Notes to fund its exploration, development and acquisition program and for general corporate purposes. Interest on 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, the Guarantors and U.S. Bank National Association, as trustee (the “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.
	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, 2014 and December 31, 2013.
	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. On March 27, 2014, the lenders under the Second Amended Credit Facility (the “Lenders”) completed their regular semi-annual redetermination of the borrowing base, resulting in an increase to the borrowing base from $1,500.0 million to $1,750.0 million. However, the Company elected to limit the Lenders’ aggregate commitment 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, 2014.
	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, 2014, 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 .90 to 1 but less than or equal 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, 2014) 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, 2014, 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 (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, 2014, the Company had $60.0 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 capacity of $1,434.8 million. As of March 31, 2014, the weighted average interest rate on borrowings under the Second Amended Credit Facility was 1.7%. The Company was in compliance with the financial covenants of the Second Amended Credit Facility as of March 31, 2014.
	Deferred financing costs. As of March 31, 2014, the Company had $40.3 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, 2014 and are being amortized over the respective terms of the Notes and the Second Amended Credit Facility. Amortization of deferred financing costs recorded for the three months ended March 31, 2014 and 2013 was $1.6 million and $0.8 million, respectively. 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, 2014
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, 2014:
		(In thousands)
	Balance at December 31, 2013	$	36,458
	Liabilities incurred during period	1,401
	Liabilities settled during period(1)	(1,974		)
	Accretion expense during period(2)	445
	Balance at March 31, 2014	$	36,330
	___________________
	-1	Liabilities settled during period represents ARO related to the properties sold in the Sanish Divestiture.
	-2	Included in depreciation, depletion and amortization on the Company’s Condensed Consolidated Statement of Operations.
	At March 31, 2014, the current portion of the total ARO balance was approximately $0.5 million and is included in accrued liabilities on the Company’s Condensed Consolidated Balance Sheet.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2014
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 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 value 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, 2014, the Company assumed annual forfeiture rates by employee group ranging from 0% to 12.7% based on the Company’s forfeiture history for this type of award.
	During the three months ended March 31, 2014, employees and non-employee directors of the Company were granted restricted stock awards equal to 588,660 shares of common stock with a $42.55 weighted average grant date per share value. Stock-based compensation expense recorded for restricted stock awards for the three months ended March 31, 2014 and 2013 was $3.9 million and $2.1 million, respectively. Stock-based compensation expense 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 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, 2014, the Company assumed an annual forfeiture rate of 3.3% based on the Company’s forfeiture history for the officer employee group receiving PSUs.
	During the three months ended March 31, 2014, officers of the Company were granted 158,970 PSUs with a $41.71 weighted average grant date per share value. Stock-based compensation expense recorded for PSUs for the three months ended March 31, 2014 and 2013 was $0.6 million and $0.3 million, respectively, and is included in general and administrative expenses on the 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, an award recipient 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 recipient 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 in stock price over a historical two-year 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, 2014:
	Forecast period (years)	4
	Risk-free interest rate	1.12	%
	Oasis stock price volatility	44.49	%
	Based on these assumptions, the Monte Carlo simulation model resulted in an expected percentage of PSUs earned of 98% for the PSUs granted during the three months ended March 31, 2014.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The Company’s effective tax rate for the three months ended March 31, 2014 and 2013 was 37.4% and 37.5%, respectively. These rates were 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. As of March 31, 2014, 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, 2014 recorded in deferred 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, 2014, management determined that a valuation allowance was not required for the tax loss carryforwards as they are expected to be fully utilized before expiration.

Earnings_Per_Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2014
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	Earnings Per Share
	Basic earnings 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 per share includes the impact of potentially dilutive non-vested restricted shares outstanding during the periods presented, unless their effect is anti-dilutive. There are no adjustments made to income available to common stockholders in the calculation of diluted earnings per share.
	The following is a calculation of the basic and diluted weighted-average shares outstanding for the three months ended March 31, 2014 and 2013:
		Three Months Ended
		March 31,
		2014	2013
		(In thousands)
	Basic weighted average common shares outstanding	99,560	92,375
	Dilution effect of stock awards at end of period	489	276
	Diluted weighted average common shares outstanding	100,049	92,651
	Anti-dilutive stock-based compensation awards	1,047	778
	Issuance of common stock. On December 9, 2013, the Company completed a public offering of 7,000,000 shares of its common stock, par value $0.01 per share, at an offering price of $44.94 per share. Net proceeds from the offering were $314.4 million, after deducting offering expenses, of which $70,000 is included in common stock and $314.3 million is included in additional paid-in capital on the Company’s Consolidated Balance Sheet. The Company used the net proceeds to repay outstanding indebtedness under its Second Amended Credit Facility, to fund its exploration, development and acquisition program and for general corporate purposes.

Business_Segment_Information

Business Segment Information	3 Months Ended
	Mar. 31, 2014
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, related 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 providing salt water disposal services. 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 expenses. Summarized financial information for the Company’s segments is shown in the following table:
		Exploration and			Well Services			Midstream Services			Consolidated
		Production
		(In thousands)
	Three Months Ended March 31, 2014:
	Revenues	$	331,847		$	52,406		$	9,353		$	393,606
	Inter-segment revenues	—			(36,579		)	(7,508		)	(44,087		)
	Total revenues	331,847			15,827			1,845			349,519
	Operating income	326,533			1,620			927			329,080
	Other income (expense)	(57,660		)	52			—			(57,608		)
	Income before income taxes	268,873			1,672			927			271,472
	Three Months Ended March 31, 2013:
	Revenues	$	241,652		$	35,768		$	4,820		$	282,240
	Inter-segment revenues	—			(30,054		)	(3,882		)	(33,936		)
	Total revenues	241,652			5,714			938			248,304
	Operating income	114,885			2,563			505			117,953
	Other income (expense)	(35,019		)	4			—			(35,015		)
	Income before income taxes	79,866			2,567			505			82,938
	Total Assets:
	As of March 31, 2014	$	4,603,244		$	76,929		$	111,911		$	4,792,084
	As of December 31, 2013	4,532,264			70,708			108,952			4,711,924

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	Lease obligations. The Company’s total rental commitments under leases for office space and other property and equipment at March 31, 2014 were $10.4 million.
	Drilling contracts. As of March 31, 2014, 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 $19.8 million as of March 31, 2014 for the days remaining through the end of the primary terms of the contracts.
	Volume commitment agreements. As of March 31, 2014, the Company had certain agreements with an aggregate requirement to deliver a minimum quantity of approximately 8.1 MMBbl and 11.4 Bcf from its Williston Basin project areas within specified timeframes, all of which are less than five years. Future obligations under these agreements were approximately $43.7 million as of March 31, 2014.
	Water purchase agreements. As of March 31, 2014, the Company had certain agreements for the purchase of freshwater with an aggregate future obligation of approximately $5.0 million.
	Cost sharing agreements. As of March 31, 2014, the Company had certain agreements to share the cost to construct and install electrical facilities. The Company’s estimated future obligation under these agreements was $11.1 million as of March 31, 2014.
	Investment commitment. As of March 31, 2014, the Company had a remaining capital spending commitment of $6.9 million in connection with drilling and completion activities that the Company agreed to fund for certain wells that were part of the Company’s acquisitions of oil and natural gas properties in its East Nesson project area during the third quarter of 2013.
	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 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 and intends to vigorously defend against them.

Condensed_Consolidating_Financ

Condensed Consolidating Financial Information	3 Months Ended
	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Condensed Consolidating Financial Information	'
	Condensed Consolidating Financial Information
	The Notes (see Note 8) 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
	(In thousands, except share data)
		31-Mar-14
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
	ASSETS
	Current assets
	Cash and cash equivalents	$	936		$	55,362		$	—		$	56,298
	Accounts receivable – oil and gas revenues	—			202,749			—			202,749
	Accounts receivable – joint interest partners	—			134,553			—			134,553
	Accounts receivable – affiliates	770			12,802			(13,572		)	—
	Inventory	—			19,862			—			19,862
	Prepaid expenses	159			24,291			—			24,450
	Deferred income taxes	—			8,484			—			8,484
	Derivative instruments	—			778			—			778
	Advances to joint interest partners	—			214			—			214
	Other current assets	—			420			—			420
	Total current assets	1,865			459,515			(13,572		)	447,808
	Property, plant and equipment
	Oil and gas properties (successful efforts method)	—			4,820,902			—			4,820,902
	Other property and equipment	—			200,158			—			200,158
	Less: accumulated depreciation, depletion, amortization and impairment	—			(723,429		)	—			(723,429		)
	Total property, plant and equipment, net	—			4,297,631			—			4,297,631
	Investments in and advances to subsidiaries	3,621,362			—			(3,621,362		)	—
	Derivative instruments	—			470			—			470
	Deferred income taxes	101,341			—			(101,341		)	—
	Deferred costs and other assets	32,862			13,313			—			46,175
	Total assets	$	3,757,430		$	4,770,929		$	(3,736,275	)	$	4,792,084
	LIABILITIES AND STOCKHOLDERS’ EQUITY
	Current liabilities
	Accounts payable	$	—		$	24,516		$	—		$	24,516
	Accounts payable – affiliates	12,802			770			(13,572		)	—
	Revenues and production taxes payable	—			183,120			—			183,120
	Accrued liabilities	119			282,905			—			283,024
	Accrued interest payable	24,527			35			—			24,562
	Derivative instruments	—			20,663			—			20,663
	Advances from joint interest partners	—			10,931			—			10,931
	Other current liabilities	—			2,766			—			2,766
	Total current liabilities	37,448			525,706			(13,572		)	549,582
	Long-term debt	2,200,000			60,000			—			2,260,000
	Deferred income taxes	—			525,390			(101,341		)	424,049
	Asset retirement obligations	—			35,790			—			35,790
	Derivative instruments	—			679			—			679
	Other liabilities	—			2,002			—			2,002
	Total liabilities	2,237,448			1,149,567			(114,913		)	3,272,102
	Stockholders’ equity
	Capital contributions from affiliates	—			2,904,739			(2,904,739		)	—
	Common stock, $0.01 par value: 300,000,000 shares authorized; 101,416,749 issued	999			—			—			999
	Treasury stock, at cost: 238,453 shares	(8,387		)	—			—			(8,387		)
	Additional paid-in capital	989,525			8,743			(8,743		)	989,525
	Retained earnings	537,845			707,880			(707,880		)	537,845
	Total stockholders’ equity	1,519,982			3,621,362			(3,621,362		)	1,519,982
	Total liabilities and stockholders’ equity	$	3,757,430		$	4,770,929		$	(3,736,275	)	$	4,792,084
	Condensed Consolidating Balance Sheet
	(In thousands, except share data)
		31-Dec-13
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
ASSETS
Current assets
Cash and cash equivalents	$	34,277		$	57,624		$	—		$	91,901
Accounts receivable – oil and gas revenues	—			175,653			—			175,653
Accounts receivable – joint interest partners	—			139,459			—			139,459
Accounts receivable – affiliates	770			9,100			(9,870		)	—
Inventory	—			20,652			—			20,652
Prepaid expenses	318			9,873			—			10,191
Deferred income taxes	—			6,335			—			6,335
Derivative instruments	—			2,264			—			2,264
Advances to joint interest partners	—			760			—			760
Other current assets	—			391			—			391
Total current assets	35,365			422,111			(9,870		)	447,606
Property, plant and equipment
Oil and gas properties (successful efforts method)	—			4,528,958			—			4,528,958
Other property and equipment	—			188,468			—			188,468
Less: accumulated depreciation, depletion, amortization and impairment	—			(637,676		)	—			(637,676		)
Total property, plant and equipment, net	—			4,079,750			—			4,079,750
Assets held for sale	—			137,066			—			137,066
Investments in and advances to subsidiaries	3,450,668			—			(3,450,668		)	—
Derivative instruments	—			1,333			—			1,333
Deferred income taxes	85,288			—			(85,288		)	—
Deferred costs and other assets	33,983			12,186			—			46,169
Total assets	$	3,605,304		$	4,652,446		$	(3,545,826	)	$	4,711,924
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities
Accounts payable	$	—		$	8,920		$	—		$	8,920
Accounts payable – affiliates	9,100			770			(9,870		)	—
Revenues and production taxes payable	—			146,741			—			146,741
Accrued liabilities	33			241,797			—			241,830
Accrued interest payable	47,622			288			—			47,910
Derivative instruments	—			8,188			—			8,188
Advances from joint interest partners	—			12,829			—			12,829
Total current liabilities	56,755			419,533			(9,870		)	466,418
Long-term debt	2,200,000			335,570			—			2,535,570
Deferred income taxes	—			408,435			(85,288		)	323,147
Asset retirement obligations	—			35,918			—			35,918
Derivative instruments	—			139			—			139
Other liabilities	—			2,183			—			2,183
Total liabilities	2,256,755			1,201,778			(95,158		)	3,363,375
Stockholders’ equity
Capital contributions from affiliates	—			2,930,978			(2,930,978		)	—
Common stock, $0.01 par value: 300,000,000 shares authorized; 100,866,589 issued	996			—			—			996
Treasury stock, at cost: 167,155 shares	(5,362		)	—			—			(5,362		)
Additional paid-in capital	985,023			8,743			(8,743		)	985,023
Retained earnings	367,892			510,947			(510,947		)	367,892
Total stockholders’ equity	1,348,549			3,450,668			(3,450,668		)	1,348,549
Total liabilities and stockholders’ equity	$	3,605,304		$	4,652,446		$	(3,545,826	)	$	4,711,924
Condensed Consolidating Statement of Operations
(In thousands)
	Three Months Ended March 31, 2014
	Parent/			Combined			Intercompany			Consolidated
	Issuer			Guarantor			Eliminations
				Subsidiaries
Revenues
Oil and gas revenues	$	—		$	331,847		$	—		$	331,847
Well services and midstream revenues	—			17,672			—			17,672
Total revenues	—			349,519			—			349,519
Expenses
Lease operating expenses	—			39,989			—			39,989
Well services and midstream operating expenses	—			10,920			—			10,920
Marketing, transportation and gathering expenses	—			5,186			—			5,186
Production taxes	—			31,803			—			31,803
Depreciation, depletion and amortization	—			91,272			—			91,272
Exploration expenses	—			380			—			380
Impairment of oil and gas properties	—			762			—			762
General and administrative expenses	5,612			17,908			—			23,520
Total expenses	5,612			198,220			—			203,832
Gain on sale of properties	—			183,393			—			183,393
Operating income (loss)	(5,612		)	334,692			—			329,080
Other income (expense)
Equity in earnings in subsidiaries	196,933			—			(196,933		)	—
Net loss on derivative instruments	—			(17,603		)	—			(17,603		)
Interest expense, net of capitalized interest	(37,424		)	(2,734		)	—			(40,158		)
Other income (expense)	3			150			—			153
Total other income (expense)	159,512			(20,187		)	(196,933		)	(57,608		)
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 Operations
(In thousands)
	Three Months Ended March 31, 2013
	Parent/			Combined			Intercompany			Consolidated
	Issuer			Guarantor			Eliminations
				Subsidiaries
Revenues
Oil and gas revenues	$	—		$	241,651		$	—		$	241,651
Well services and midstream revenues	—			6,653			—			6,653
Total revenues	—			248,304			—			248,304
Expenses
Lease operating expenses	—			19,489			—			19,489
Well services and midstream operating expenses	—			2,914			—			2,914
Marketing, transportation and gathering expenses	—			3,389			—			3,389
Production taxes	—			22,089			—			22,089
Depreciation, depletion and amortization	—			66,261			—			66,261
Exploration expenses	—			1,857			—			1,857
Impairment of oil and gas properties	—			498			—			498
General and administrative expenses	2,876			10,978			—			13,854
Total expenses	2,876			127,475			—			130,351
Operating income (loss)	(2,876		)	120,829			—			117,953
Other income (expense)
Equity in earnings in subsidiaries	66,243			—			(66,243		)	—
Net loss on derivative instruments	—			(14,612		)	—			(14,612		)
Interest expense, net of capitalized interest	(20,518		)	(665		)	—			(21,183		)
Other income (expense)	376			404			—			780
Total other income (expense)	46,101			(14,873		)	(66,243		)	(35,015		)
Income before income taxes	43,225			105,956			(66,243		)	82,938
Income tax benefit (expense)	8,626			(39,713		)	—			(31,087		)
Net income	$	51,851		$	66,243		$	(66,243	)	$	51,851
Condensed Consolidating Statement of Cash Flows
(In thousands)
	Three Months Ended March 31, 2014
	Parent/			Combined			Intercompany			Consolidated
	Issuer			Guarantor			Eliminations
				Subsidiaries
Cash flows from operating activities:
Net income	$	169,953		$	196,933		$	(196,933	)	$	169,953
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Equity in earnings of subsidiaries	(196,933		)	—			196,933			—
Depreciation, depletion and amortization	—			91,272			—			91,272
Gain on sale of properties	—			(183,393		)				(183,393		)
Impairment of oil and gas properties	—			762			—			762
Deferred income taxes	(16,053		)	114,806			—			98,753
Derivative instruments	—			17,603			—			17,603
Stock-based compensation expenses	4,428			77			—			4,505
Debt discount amortization and other	1,123			364			—			1,487
Working capital and other changes:
Change in accounts receivable	—			(12,977		)	3,702			(9,275		)
Change in inventory	—			790			—			790
Change in prepaid expenses	159			(14,418		)	—			(14,259		)
Change in other current assets	—			(29		)	—			(29		)
Change in other assets	—			(1,593		)	—			(1,593		)
Change in accounts payable and accrued liabilities	(19,307		)	52,016			(3,702		)	29,007
Change in other current liabilities	—			2,766			—			2,766
Change in other liabilities	—			(82		)	—			(82		)
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
Costs related to sale of properties	—			(2,010		)				(2,010		)
Derivative settlements	—			(2,239		)	—			(2,239		)
Advances from joint interest partners	—			(1,898		)	—			(1,898		)
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		)
Purchases of treasury stock	(3,025		)	—			—			(3,025		)
Investment in / capital contributions from affiliates	26,490			(26,490		)	—			—
Other	(176		)	—			—			(176		)
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
Condensed Consolidating Statement of Cash Flows
(In thousands)
	Three Months Ended March 31, 2013
	Parent/			Combined			Intercompany			Consolidated
	Issuer			Guarantor			Eliminations
				Subsidiaries
Cash flows from operating activities:
Net income	$	51,851		$	66,243		$	(66,243	)	$	51,851
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Equity in earnings of subsidiaries	(66,243		)	—			66,243			—
Depreciation, depletion and amortization	—			66,261			—			66,261
Impairment of oil and gas properties	—			498			—			498
Deferred income taxes	(8,626		)	39,613			—			30,987
Derivative instruments	—			14,612			—			14,612
Stock-based compensation expenses	2,278			11			—			2,289
Debt discount amortization and other	644			102			—			746
Working capital and other changes:
Change in accounts receivable	11			(3,740		)	369			(3,360		)
Change in inventory	—			(8,407		)	—			(8,407		)
Change in prepaid expenses	157			136			—			293
Change in other current assets	(339		)	107			—			(232		)
Change in accounts payable and accrued liabilities	(8,286		)	23,664			(369		)	15,009
Net cash provided by (used in) operating activities	(28,553		)	199,100			—			170,547
Cash flows from investing activities:
Capital expenditures	—			(217,819		)	—			(217,819		)
Derivative settlements	—			1,686			—			1,686
Advances from joint interest partners	—			(1,691		)	—			(1,691		)
Net cash used in investing activities	—			(217,824		)	—			(217,824		)
Cash flows from financing activities:
Purchases of treasury stock	(156		)	—			—			(156		)
Debt issuance costs	—			(25		)	—			(25		)
Investment in / capital contributions from affiliates	(23,252		)	23,252			—			—
Net cash provided by (used in) financing activities	(23,408		)	23,227			—			(181		)
Increase (decrease) in cash and cash equivalents	(51,961		)	4,503			—			(47,458		)
Cash and cash equivalents at beginning of period	133,797			79,650			—			213,447
Cash and cash equivalents at end of period	$	81,836		$	84,153		$	—		$	165,989

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2014
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.
	Lease obligations. In April 2014, the Company entered into an amendment to its lease agreement for office space, which increased its total rental commitments under leases to $27.6 million as of the date of this report.
	Drilling contracts. In April 2014, the Company entered into additional 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 $21.9 million as of the date of this report.
	Derivative instruments. In April 2014, the Company entered into new swap agreements, which settle monthly based on the WTI crude oil index price, for a total notional amount of 1,092,000 barrels in 2015. These derivative instruments do not qualify for and were not designated as hedging instruments for accounting purposes.

Organization_and_Operations_of1

Organization and Operations of the Company (Policies)	3 Months Ended
	Mar. 31, 2014
Accounting Policies [Abstract]	'
Organization	'
	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. In 2007, Oasis Petroleum North America LLC (“OPNA”), a Delaware limited liability company, was formed to conduct 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. As part of the formation of OMS, the Company transferred substantially all of its salt water disposal and other midstream assets from OPNA to OMS.
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, 2013 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, 2013 (“2013 Annual Report”).
Significant Accounting Policies	'
	Significant Accounting Policies
	There have been no material changes to the Company’s critical accounting policies and estimates from those disclosed in the 2013 Annual Report.

Inventory_Tables

Inventory (Tables)	3 Months Ended
	Mar. 31, 2014
Inventory Disclosure [Abstract]	'
Schedule of Inventory	'
	Inventory consists of the following:
		March 31, 2014		December 31, 2013
		(In thousands)
	Equipment and materials	$	10,207	$	11,669
	Crude oil inventory	9,655		8,983
	Total inventory	$	19,862	$	20,652

Property_Plant_and_Equipment_T

Property, Plant and Equipment (Tables)	3 Months Ended
	Mar. 31, 2014
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-14			31-Dec-13
		(In thousands)
	Proved oil and gas properties(1)	$	3,985,490		$	3,713,525
	Less: Accumulated depreciation, depletion, amortization and impairment	(693,011		)	(612,380		)
	Proved oil and gas properties, net	3,292,479			3,101,145
	Unproved oil and gas properties	835,412			815,433
	Total oil and gas properties, net	4,127,891			3,916,578
	Other property and equipment	200,158			188,468
	Less: Accumulated depreciation	(30,418		)	(25,296		)
	Other property and equipment, net	169,740			163,172
	Total property, plant and equipment, net	$	4,297,631		$	4,079,750
	__________________
	-1	Included in the Company’s proved oil and gas properties are estimates of future asset retirement costs of $32.1 million and $32.6 million at March 31, 2014 and December 31, 2013, respectively.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2014
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, 2014
		Level 1		Level 2		Level 3		Total
		(In thousands)
	Assets:
	Money market funds	$	742	$	—	$	—	$	742
	Commodity derivative instruments (see Note 7)	—		1,248		—		1,248
	Total assets	$	742	$	1,248	$	—	$	1,990
	Liabilities:
	Commodity derivative instruments (see Note 7)	$	—	$	21,342	$	—	$	21,342
	Total liabilities	$	—	$	21,342	$	—	$	21,342
		At fair value as of December 31, 2013
		Level 1		Level 2		Level 3		Total
		(In thousands)
	Assets:
	Money market funds	$	742	$	—	$	—	$	742
	Commodity derivative instruments (see Note 7)	—		3,597		—		3,597
	Total assets	$	742	$	3,597	$	—	$	4,339
	Liabilities:
	Commodity derivative instruments (see Note 7)	$	—	$	8,327	$	—	$	8,327
	Total liabilities	$	—	$	8,327	$	—	$	8,327

Derivative_Instruments_Tables

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Schedule of Outstanding Commodity Derivative Instruments	'
	As of March 31, 2014, the Company had the following outstanding commodity derivative instruments, all of which settle monthly based on the average WTI crude oil index price:
	Settlement		Derivative		Total Notional			Weighted Average Prices										Fair Value
	Period		Instrument		Amount of Oil													Asset
								Swap				Sub-Floor		Floor		Ceiling		(Liability)
					(Barrels)			($/Barrel)										(In thousands)
	2014		Two-way collars		993,500									$	90	$	100.91	$	(1,433	)
	2014		Three-way collars		2,581,500							$	70.53	$	90.53	$	105.13	(339		)
	2014		Swaps		3,094,500			$	96.45									(7,101		)
	2014		Swaps with sub-floors		1,650,000			$	92.6			$	70					(9,636		)
	2015		Two-way collars		108,500									$	90	$	99.86	71
	2015		Three-way collars		263,500							$	70.59	$	90.59	$	105.25	458
	2015		Swaps		3,384,500			$	90.27									(2,164		)
	2015		Swaps with sub-floors		186,000			$	92.6			$	70					(349		)
	2016		Swaps		186,000			$	89.39									399
																		$	(20,094	)
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 balance sheet for the periods presented:
	Fair Value of Derivative Instrument Assets (Liabilities)
					Fair Value
	Commodity		Balance Sheet Location		March 31, 2014				31-Dec-13
					(In thousands)
	Crude oil		Derivative instruments — current assets		$	778			$	2,264
	Crude oil		Derivative instruments — non-current assets		470				1,333
	Crude oil		Derivative instruments — current liabilities		(20,663		)		(8,188		)
	Crude oil		Derivative instruments — non-current liabilities		(679		)		(139		)
	Total derivative instruments				$	(20,094	)		$	(4,730	)
Realized and Unrealized 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		2014				2013
				(In thousands)
	Change in fair value of derivative instruments	Net loss on derivative instruments		$	(15,364	)		$	(16,298	)
	Derivative settlements	Net loss on derivative instruments		(2,239		)		1,686
	Total net loss on derivative instruments			$	(17,603	)		$	(14,612	)
Summary of Gross and Net Information about Commodity Derivative Instruments	'
	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, 2014		$	23,775			$	(22,527	)		$	1,248
	As of December 31, 2013		22,743				(19,146		)		3,597
	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, 2014		$	43,869			$	(22,527	)		$	21,342
	As of December 31, 2013		27,473				(19,146		)		8,327

LongTerm_Debt_Tables

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2014
Debt Disclosure [Abstract]	'
Schedule of Long-Term Debt Interest Rate	'
	As of March 31, 2014, 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 .90 to 1 but less than or equal 1	2.5	%	1	%

Asset_Retirement_Obligations_T

Asset Retirement Obligations (Tables)	3 Months Ended
	Mar. 31, 2014
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, 2014:
		(In thousands)
	Balance at December 31, 2013	$	36,458
	Liabilities incurred during period	1,401
	Liabilities settled during period(1)	(1,974		)
	Accretion expense during period(2)	445
	Balance at March 31, 2014	$	36,330
	___________________
	-1	Liabilities settled during period represents ARO related to the properties sold in the Sanish Divestiture.
	-2	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, 2014
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, 2014:
	Forecast period (years)	4
	Risk-free interest rate	1.12	%
	Oasis stock price volatility	44.49	%

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2014
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, 2014 and 2013:
		Three Months Ended
		March 31,
		2014	2013
		(In thousands)
	Basic weighted average common shares outstanding	99,560	92,375
	Dilution effect of stock awards at end of period	489	276
	Diluted weighted average common shares outstanding	100,049	92,651
	Anti-dilutive stock-based compensation awards	1,047	778

Business_Segment_Information_T

Business Segment Information (Tables)	3 Months Ended
	Mar. 31, 2014
Segment Reporting [Abstract]	'
Summarized Financial Information of Segments	'
	Summarized financial information for the Company’s segments is shown in the following table:
		Exploration and			Well Services			Midstream Services			Consolidated
		Production
		(In thousands)
	Three Months Ended March 31, 2014:
	Revenues	$	331,847		$	52,406		$	9,353		$	393,606
	Inter-segment revenues	—			(36,579		)	(7,508		)	(44,087		)
	Total revenues	331,847			15,827			1,845			349,519
	Operating income	326,533			1,620			927			329,080
	Other income (expense)	(57,660		)	52			—			(57,608		)
	Income before income taxes	268,873			1,672			927			271,472
	Three Months Ended March 31, 2013:
	Revenues	$	241,652		$	35,768		$	4,820		$	282,240
	Inter-segment revenues	—			(30,054		)	(3,882		)	(33,936		)
	Total revenues	241,652			5,714			938			248,304
	Operating income	114,885			2,563			505			117,953
	Other income (expense)	(35,019		)	4			—			(35,015		)
	Income before income taxes	79,866			2,567			505			82,938
	Total Assets:
	As of March 31, 2014	$	4,603,244		$	76,929		$	111,911		$	4,792,084
	As of December 31, 2013	4,532,264			70,708			108,952			4,711,924

Condensed_Consolidating_Financ1

Condensed Consolidating Financial Information (Tables)	3 Months Ended
	Mar. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Condensed Consolidating Balance Sheet	'
	Condensed Consolidating Balance Sheet
	(In thousands, except share data)
		31-Mar-14
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
	ASSETS
	Current assets
	Cash and cash equivalents	$	936		$	55,362		$	—		$	56,298
	Accounts receivable – oil and gas revenues	—			202,749			—			202,749
	Accounts receivable – joint interest partners	—			134,553			—			134,553
	Accounts receivable – affiliates	770			12,802			(13,572		)	—
	Inventory	—			19,862			—			19,862
	Prepaid expenses	159			24,291			—			24,450
	Deferred income taxes	—			8,484			—			8,484
	Derivative instruments	—			778			—			778
	Advances to joint interest partners	—			214			—			214
	Other current assets	—			420			—			420
	Total current assets	1,865			459,515			(13,572		)	447,808
	Property, plant and equipment
	Oil and gas properties (successful efforts method)	—			4,820,902			—			4,820,902
	Other property and equipment	—			200,158			—			200,158
	Less: accumulated depreciation, depletion, amortization and impairment	—			(723,429		)	—			(723,429		)
	Total property, plant and equipment, net	—			4,297,631			—			4,297,631
	Investments in and advances to subsidiaries	3,621,362			—			(3,621,362		)	—
	Derivative instruments	—			470			—			470
	Deferred income taxes	101,341			—			(101,341		)	—
	Deferred costs and other assets	32,862			13,313			—			46,175
	Total assets	$	3,757,430		$	4,770,929		$	(3,736,275	)	$	4,792,084
	LIABILITIES AND STOCKHOLDERS’ EQUITY
	Current liabilities
	Accounts payable	$	—		$	24,516		$	—		$	24,516
	Accounts payable – affiliates	12,802			770			(13,572		)	—
	Revenues and production taxes payable	—			183,120			—			183,120
	Accrued liabilities	119			282,905			—			283,024
	Accrued interest payable	24,527			35			—			24,562
	Derivative instruments	—			20,663			—			20,663
	Advances from joint interest partners	—			10,931			—			10,931
	Other current liabilities	—			2,766			—			2,766
	Total current liabilities	37,448			525,706			(13,572		)	549,582
	Long-term debt	2,200,000			60,000			—			2,260,000
	Deferred income taxes	—			525,390			(101,341		)	424,049
	Asset retirement obligations	—			35,790			—			35,790
	Derivative instruments	—			679			—			679
	Other liabilities	—			2,002			—			2,002
	Total liabilities	2,237,448			1,149,567			(114,913		)	3,272,102
	Stockholders’ equity
	Capital contributions from affiliates	—			2,904,739			(2,904,739		)	—
	Common stock, $0.01 par value: 300,000,000 shares authorized; 101,416,749 issued	999			—			—			999
	Treasury stock, at cost: 238,453 shares	(8,387		)	—			—			(8,387		)
	Additional paid-in capital	989,525			8,743			(8,743		)	989,525
	Retained earnings	537,845			707,880			(707,880		)	537,845
	Total stockholders’ equity	1,519,982			3,621,362			(3,621,362		)	1,519,982
	Total liabilities and stockholders’ equity	$	3,757,430		$	4,770,929		$	(3,736,275	)	$	4,792,084
		31-Dec-13
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
	ASSETS
	Current assets
	Cash and cash equivalents	$	34,277		$	57,624		$	—		$	91,901
	Accounts receivable – oil and gas revenues	—			175,653			—			175,653
	Accounts receivable – joint interest partners	—			139,459			—			139,459
Accounts receivable – affiliates	770			9,100			(9,870		)	—
Inventory	—			20,652			—			20,652
Prepaid expenses	318			9,873			—			10,191
Deferred income taxes	—			6,335			—			6,335
Derivative instruments	—			2,264			—			2,264
Advances to joint interest partners	—			760			—			760
Other current assets	—			391			—			391
Total current assets	35,365			422,111			(9,870		)	447,606
Property, plant and equipment
Oil and gas properties (successful efforts method)	—			4,528,958			—			4,528,958
Other property and equipment	—			188,468			—			188,468
Less: accumulated depreciation, depletion, amortization and impairment	—			(637,676		)	—			(637,676		)
Total property, plant and equipment, net	—			4,079,750			—			4,079,750
Assets held for sale	—			137,066			—			137,066
Investments in and advances to subsidiaries	3,450,668			—			(3,450,668		)	—
Derivative instruments	—			1,333			—			1,333
Deferred income taxes	85,288			—			(85,288		)	—
Deferred costs and other assets	33,983			12,186			—			46,169
Total assets	$	3,605,304		$	4,652,446		$	(3,545,826	)	$	4,711,924
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities
Accounts payable	$	—		$	8,920		$	—		$	8,920
Accounts payable – affiliates	9,100			770			(9,870		)	—
Revenues and production taxes payable	—			146,741			—			146,741
Accrued liabilities	33			241,797			—			241,830
Accrued interest payable	47,622			288			—			47,910
Derivative instruments	—			8,188			—			8,188
Advances from joint interest partners	—			12,829			—			12,829
Total current liabilities	56,755			419,533			(9,870		)	466,418
Long-term debt	2,200,000			335,570			—			2,535,570
Deferred income taxes	—			408,435			(85,288		)	323,147
Asset retirement obligations	—			35,918			—			35,918
Derivative instruments	—			139			—			139
Other liabilities	—			2,183			—			2,183
Total liabilities	2,256,755			1,201,778			(95,158		)	3,363,375
Stockholders’ equity
Capital contributions from affiliates	—			2,930,978			(2,930,978		)	—
Common stock, $0.01 par value: 300,000,000 shares authorized; 100,866,589 issued	996			—			—			996
Treasury stock, at cost: 167,155 shares	(5,362		)	—			—			(5,362		)
Additional paid-in capital	985,023			8,743			(8,743		)	985,023
Retained earnings	367,892			510,947			(510,947		)	367,892
Total stockholders’ equity	1,348,549			3,450,668			(3,450,668		)	1,348,549
Total liabilities and stockholders’ equity	$	3,605,304		$	4,652,446		$	(3,545,826	)	$	4,711,924
Condensed Consolidating Statement of Operations	'
	Condensed Consolidating Statement of Operations
	(In thousands)
		Three Months Ended March 31, 2014
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
	Revenues
	Oil and gas revenues	$	—		$	331,847		$	—		$	331,847
	Well services and midstream revenues	—			17,672			—			17,672
	Total revenues	—			349,519			—			349,519
	Expenses
	Lease operating expenses	—			39,989			—			39,989
	Well services and midstream operating expenses	—			10,920			—			10,920
	Marketing, transportation and gathering expenses	—			5,186			—			5,186
	Production taxes	—			31,803			—			31,803
	Depreciation, depletion and amortization	—			91,272			—			91,272
	Exploration expenses	—			380			—			380
	Impairment of oil and gas properties	—			762			—			762
	General and administrative expenses	5,612			17,908			—			23,520
	Total expenses	5,612			198,220			—			203,832
	Gain on sale of properties	—			183,393			—			183,393
	Operating income (loss)	(5,612		)	334,692			—			329,080
	Other income (expense)
	Equity in earnings in subsidiaries	196,933			—			(196,933		)	—
	Net loss on derivative instruments	—			(17,603		)	—			(17,603		)
	Interest expense, net of capitalized interest	(37,424		)	(2,734		)	—			(40,158		)
	Other income (expense)	3			150			—			153
	Total other income (expense)	159,512			(20,187		)	(196,933		)	(57,608		)
	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 Operations
	(In thousands)
		Three Months Ended March 31, 2013
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
	Revenues
	Oil and gas revenues	$	—		$	241,651		$	—		$	241,651
	Well services and midstream revenues	—			6,653			—			6,653
	Total revenues	—			248,304			—			248,304
	Expenses
	Lease operating expenses	—			19,489			—			19,489
	Well services and midstream operating expenses	—			2,914			—			2,914
	Marketing, transportation and gathering expenses	—			3,389			—			3,389
	Production taxes	—			22,089			—			22,089
	Depreciation, depletion and amortization	—			66,261			—			66,261
	Exploration expenses	—			1,857			—			1,857
	Impairment of oil and gas properties	—			498			—			498
	General and administrative expenses	2,876			10,978			—			13,854
	Total expenses	2,876			127,475			—			130,351
	Operating income (loss)	(2,876		)	120,829			—			117,953
	Other income (expense)
	Equity in earnings in subsidiaries	66,243			—			(66,243		)	—
	Net loss on derivative instruments	—			(14,612		)	—			(14,612		)
	Interest expense, net of capitalized interest	(20,518		)	(665		)	—			(21,183		)
	Other income (expense)	376			404			—			780
	Total other income (expense)	46,101			(14,873		)	(66,243		)	(35,015		)
	Income before income taxes	43,225			105,956			(66,243		)	82,938
	Income tax benefit (expense)	8,626			(39,713		)	—			(31,087		)
	Net income	$	51,851		$	66,243		$	(66,243	)	$	51,851
Condensed Consolidating Statement of Cash Flows	'
	Condensed Consolidating Statement of Cash Flows
	(In thousands)
		Three Months Ended March 31, 2014
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
	Cash flows from operating activities:
	Net income	$	169,953		$	196,933		$	(196,933	)	$	169,953
	Adjustments to reconcile net income to net cash provided by (used in) operating activities:
	Equity in earnings of subsidiaries	(196,933		)	—			196,933			—
	Depreciation, depletion and amortization	—			91,272			—			91,272
	Gain on sale of properties	—			(183,393		)				(183,393		)
	Impairment of oil and gas properties	—			762			—			762
	Deferred income taxes	(16,053		)	114,806			—			98,753
	Derivative instruments	—			17,603			—			17,603
	Stock-based compensation expenses	4,428			77			—			4,505
	Debt discount amortization and other	1,123			364			—			1,487
	Working capital and other changes:
	Change in accounts receivable	—			(12,977		)	3,702			(9,275		)
	Change in inventory	—			790			—			790
	Change in prepaid expenses	159			(14,418		)	—			(14,259		)
	Change in other current assets	—			(29		)	—			(29		)
	Change in other assets	—			(1,593		)	—			(1,593		)
	Change in accounts payable and accrued liabilities	(19,307		)	52,016			(3,702		)	29,007
	Change in other current liabilities	—			2,766			—			2,766
	Change in other liabilities	—			(82		)	—			(82		)
	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
	Costs related to sale of properties	—			(2,010		)				(2,010		)
	Derivative settlements	—			(2,239		)	—			(2,239		)
	Advances from joint interest partners	—			(1,898		)	—			(1,898		)
	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		)
	Purchases of treasury stock	(3,025		)	—			—			(3,025		)
	Investment in / capital contributions from affiliates	26,490			(26,490		)	—			—
	Other	(176		)	—			—			(176		)
	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
	Condensed Consolidating Statement of Cash Flows
	(In thousands)
		Three Months Ended March 31, 2013
		Parent/			Combined			Intercompany			Consolidated
		Issuer			Guarantor			Eliminations
					Subsidiaries
	Cash flows from operating activities:
	Net income	$	51,851		$	66,243		$	(66,243	)	$	51,851
	Adjustments to reconcile net income to net cash provided by (used in) operating activities:
	Equity in earnings of subsidiaries	(66,243		)	—			66,243			—
	Depreciation, depletion and amortization	—			66,261			—			66,261
	Impairment of oil and gas properties	—			498			—			498
	Deferred income taxes	(8,626		)	39,613			—			30,987
	Derivative instruments	—			14,612			—			14,612
	Stock-based compensation expenses	2,278			11			—			2,289
	Debt discount amortization and other	644			102			—			746
	Working capital and other changes:
	Change in accounts receivable	11			(3,740		)	369			(3,360		)
	Change in inventory	—			(8,407		)	—			(8,407		)
	Change in prepaid expenses	157			136			—			293
Change in other current assets	(339		)	107			—			(232		)
Change in accounts payable and accrued liabilities	(8,286		)	23,664			(369		)	15,009
Net cash provided by (used in) operating activities	(28,553		)	199,100			—			170,547
Cash flows from investing activities:
Capital expenditures	—			(217,819		)	—			(217,819		)
Derivative settlements	—			1,686			—			1,686
Advances from joint interest partners	—			(1,691		)	—			(1,691		)
Net cash used in investing activities	—			(217,824		)	—			(217,824		)
Cash flows from financing activities:
Purchases of treasury stock	(156		)	—			—			(156		)
Debt issuance costs	—			(25		)	—			(25		)
Investment in / capital contributions from affiliates	(23,252		)	23,252			—			—
Net cash provided by (used in) financing activities	(23,408		)	23,227			—			(181		)
Increase (decrease) in cash and cash equivalents	(51,961		)	4,503			—			(47,458		)
Cash and cash equivalents at beginning of period	133,797			79,650			—			213,447
Cash and cash equivalents at end of period	$	81,836		$	84,153		$	—		$	165,989

Inventory_Schedule_of_Inventor

Inventory - Schedule of Inventory (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Inventory Disclosure [Abstract]	'	'
Equipment and materials	$10,207	$11,669
Crude oil inventory	9,655	8,983
Total inventory	$19,862	$20,652

Property_Plant_and_Equipment_S

Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Detail) (USD $)	Mar. 31, 2014		Dec. 31, 2013
In Thousands, unless otherwise specified
Property, Plant and Equipment [Abstract]	'		'
Proved oil and gas properties	$3,985,490	[1]	$3,713,525	[1]
Less: Accumulated depreciation, depletion, amortization and impairment	-693,011		-612,380
Proved oil and gas properties, net	3,292,479	[2]	3,101,145	[2]
Unproved oil and gas properties	835,412		815,433
Total oil and gas properties, net	4,127,891		3,916,578
Other property and equipment	200,158		188,468
Less: Accumulated depreciation	-30,418		-25,296
Other property and equipment, net	169,740	[2]	163,172	[2]
Total property, plant and equipment, net	$4,297,631		$4,079,750
[1]	Included in the Company’s proved oil and gas properties are estimates of future asset retirement costs of $32.1 million and $32.6 million at March 31, 2014 and December 31, 2013, respectively.
[2]	{F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOjNkMjhjMTZiYzUyMTQ5ZTdiNjI0YWNlZjM4ZmExYjdhfFRleHRTZWxlY3Rpb246NUQyOUI2RjJERUQzNDcyNjBFNENCMkNBREE1OENBNkYM}

Property_Plant_and_Equipment_S1

Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Parenthetical) (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Property, Plant and Equipment [Abstract]	'	'
Asset retirement costs	$32.10	$32.60

Property_Plant_and_Equipment_A

Property, Plant and Equipment - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Property, Plant and Equipment [Line Items]	'	'
Impairment of oil and gas properties	$762	$498
Unproved property leases [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Impairment of oil and gas properties	$800	$498

Divestiture_Details

Divestiture (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Discontinued Operations and Disposal Groups [Abstract]	'	'
Cash proceeds from sale of non-operated properties	$321,943	$0
Gain on sale of properties	$183,393	$0

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, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets:	'	'
Total assets	$1,990	$4,339
Liabilities:	'	'
Total liabilities	21,342	8,327
Money market funds [Member]	'	'
Assets:	'	'
Total assets	742	742
Commodity derivative instruments [Member]	'	'
Assets:	'	'
Total assets	1,248	3,597
Liabilities:	'	'
Total liabilities	21,342	8,327
Level 1 [Member]	'	'
Assets:	'	'
Total assets	742	742
Liabilities:	'	'
Total liabilities	'	'
Level 1 [Member] | Money market funds [Member]	'	'
Assets:	'	'
Total assets	742	742
Level 1 [Member] | Commodity derivative instruments [Member]	'	'
Assets:	'	'
Total assets	'	'
Liabilities:	'	'
Total liabilities	'	'
Level 2 [Member]	'	'
Assets:	'	'
Total assets	1,248	3,597
Liabilities:	'	'
Total liabilities	21,342	8,327
Level 2 [Member] | Money market funds [Member]	'	'
Assets:	'	'
Total assets	'	'
Level 2 [Member] | Commodity derivative instruments [Member]	'	'
Assets:	'	'
Total assets	1,248	3,597
Liabilities:	'	'
Total liabilities	21,342	8,327
Fair Value, Inputs, Level 3 [Member]	'	'
Assets:	'	'
Total assets	'	'
Liabilities:	'	'
Total liabilities	'	'
Fair Value, Inputs, Level 3 [Member] | Money market funds [Member]	'	'
Assets:	'	'
Total assets	'	'
Fair Value, Inputs, Level 3 [Member] | Commodity derivative instruments [Member]	'	'
Assets:	'	'
Total assets	'	'
Liabilities:	'	'
Total liabilities	'	'

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]	'	'
Derivative credit risk valuation adjustment, derivative assets	$300,000	$200,000
Long-term debt	2,260,000,000	2,535,570,000
Asset retirement obligation, carrying value	36,330,000	36,458,000
Senior Unsecured Debt [Member]	'	'
Debt Instrument [Line Items]	'	'
Long-term debt	2,200,000,000	'
Long-term debt, fair value	2,374,500,000	'
Second Amended Credit Facility [Member]	'	'
Debt Instrument [Line Items]	'	'
Long-term debt	$60,000,000	'

Derivative_Instruments_Schedul

Derivative Instruments - Schedule of Outstanding Commodity Derivative Instruments (Detail) (USD $)	Mar. 31, 2014
In Thousands, unless otherwise specified
Derivative [Line Items]	'
Fair Value Asset (Liability)	($20,094)
2014 Two-Way Collars [Member]	'
Derivative [Line Items]	'
Settlement Period	'2014
Total Notional Amount of Oil (Barrels)	993,500
Average Floor Price (in dollars per barrel)	90
Average Ceiling Price (in dollars per barrel)	100.91
Fair Value Asset (Liability)	-1,433
2014 Three-Way Collars [Member]	'
Derivative [Line Items]	'
Settlement Period	'2014
Total Notional Amount of Oil (Barrels)	2,581,500
Average Sub-Floor Price (in dollars per barrel)	70.53
Average Floor Price (in dollars per barrel)	90.53
Average Ceiling Price (in dollars per barrel)	105.13
Fair Value Asset (Liability)	-339
2014 Swaps [Member]	'
Derivative [Line Items]	'
Settlement Period	'2014
Total Notional Amount of Oil (Barrels)	3,094,500
Average Swap Price (in dollars per barrel)	96.45
Fair Value Asset (Liability)	-7,101
2014 Swaps with sub-floors [Member]	'
Derivative [Line Items]	'
Settlement Period	'2014
Total Notional Amount of Oil (Barrels)	1,650,000
Average Swap Price (in dollars per barrel)	92.6
Average Sub-Floor Price (in dollars per barrel)	70
Fair Value Asset (Liability)	-9,636
2015 Two-Way Collars [Member]	'
Derivative [Line Items]	'
Settlement Period	'2015
Total Notional Amount of Oil (Barrels)	108,500
Average Floor Price (in dollars per barrel)	90
Average Ceiling Price (in dollars per barrel)	99.86
Fair Value Asset (Liability)	71
2015 Three-Way Collars [Member]	'
Derivative [Line Items]	'
Settlement Period	'2015
Total Notional Amount of Oil (Barrels)	263,500
Average Sub-Floor Price (in dollars per barrel)	70.59
Average Floor Price (in dollars per barrel)	90.59
Average Ceiling Price (in dollars per barrel)	105.25
Fair Value Asset (Liability)	458
2015 Swaps [Member]	'
Derivative [Line Items]	'
Settlement Period	'2015
Total Notional Amount of Oil (Barrels)	3,384,500
Average Swap Price (in dollars per barrel)	90.27
Fair Value Asset (Liability)	-2,164
2015 Swaps with sub-floors [Member]	'
Derivative [Line Items]	'
Settlement Period	'2015
Total Notional Amount of Oil (Barrels)	186,000
Average Swap Price (in dollars per barrel)	92.6
Average Sub-Floor Price (in dollars per barrel)	70
Fair Value Asset (Liability)	-349
2016 Swaps [Member]	'
Derivative [Line Items]	'
Settlement Period	'2016
Total Notional Amount of Oil (Barrels)	186,000
Average Swap Price (in dollars per barrel)	89.39
Fair Value Asset (Liability)	$399

Derivative_Instruments_Schedul1

Derivative Instruments - Schedule of Location and Fair Value of Outstanding Commodity Derivative Instruments (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]	'	'
Derivative instruments — current assets	$778	$2,264
Derivative instruments — non-current assets	470	1,333
Derivative instruments — current liabilities	-20,663	-8,188
Derivative instruments — non-current liabilities	-679	-139
Total derivative instruments	-20,094	'
Crude oil [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Derivative instruments — current assets	778	2,264
Derivative instruments — non-current assets	470	1,333
Derivative instruments — current liabilities	-20,663	-8,188
Derivative instruments — non-current liabilities	-679	-139
Total derivative instruments	($20,094)	($4,730)

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, 2014	Mar. 31, 2013
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'	'
Change in fair value of derivative instruments	($15,364)	($16,298)
Derivative settlements	-2,239	1,686
Total net loss on derivative instruments	($17,603)	($14,612)

Derivative_Instruments_Summary

Derivative Instruments - Summary of Gross and Net Information about Commodity Derivative Instruments (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'	'
Gross Amounts of Recognized Assets	$23,775	$22,743
Derivative Assets, Gross Amounts Offset in the Balance Sheet	-22,527	-19,146
Net Amounts of Assets Presented in the Balance Sheet	1,248	3,597
Gross Amounts of Recognized Liabilities	43,869	27,473
Derivative Liabilities, Gross Amounts Offset in the Balance Sheet	-22,527	-19,146
Net Amounts of Liabilities Presented in the Balance Sheet	$21,342	$8,327

LongTerm_Debt_Additional_Infor

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

3 Months Ended

24 Months Ended

3 Months Ended

3 Months Ended

0 Months Ended

24 Months Ended

Mar. 31, 2014

Mar. 31, 2013

Mar. 31, 2014

Dec. 31, 2012

Mar. 31, 2014

Mar. 27, 2014

Apr. 05, 2013

Mar. 31, 2014

Mar. 31, 2014

Sep. 24, 2013

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2012

Dec. 31, 2013

Senior Unsecured Debt [Member]

Senior Unsecured Debt [Member]

Second Amended Credit Facility [Member]

Second Amended Credit Facility [Member]

Second Amended Credit Facility [Member]

Current Ratio [Member]

Minimum [Member]

2022 Notes [Member]

2019 Notes [Member]

2021 Notes [Member]

2023 Notes [Member]

2023 Notes [Member]

Second Amended Credit Facility [Member]

Second Amended Credit Facility [Member]

Senior Unsecured Debt [Member]

Senior Unsecured Debt [Member]

Senior Unsecured Debt [Member]

Senior Unsecured Debt [Member]

Senior Unsecured Debt [Member]

Debt Disclosure [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Principal debt amount

'

'

'

'

'

'

'

'

'

$1,000,000,000

$400,000,000

$400,000,000

'

$400,000,000

Stated interest rate

'

'

'

'

'

'

'

'

'

6.88%

7.25%

6.50%

'

6.88%

Debt instrument, maturity date

'

'

'

'

5-Apr-18

'

'

'

'

15-Mar-22

1-Feb-19

1-Nov-21

15-Jan-23

'

Line of credit facility maximum increase to aggregate commitments

'

'

'

'

'

1,750,000,000

1,500,000,000

'

'

'

'

'

'

'

Net proceeds from issuance of notes

'

'

'

1,175,800,000

'

'

'

'

'

983,600,000

'

'

'

'

Exchange term

'

'

'

'

'

'

'

'

'

'360 days

'

'

'

'

Exchange increase in interest rate

'

'

'

'

'

'

'

'

'

1.00%

'

'

'

'

Senior unsecured notes payment frequency

'

'

'semi-annually

'

'

'

'

'

'

'

'

'

'

'

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

'

'

'

'

'

'

'

'

'

'

'

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

'

'

'

'

'

'

'

'

'

Percentage of the reserve value of assets as determined by reserve reports (at least 80%)

'

'

'

'

'

'

'

'

80.00%

'

'

'

'

'

Commitment fee of borrowing base capacity not utilized

'

'

'

'

0.38%

'

'

'

'

'

'

'

'

'

Ratio of EBITDAX to interest expense necessary to maintain covenants

'

'

'

'

'

'

'

'

2.5

'

'

'

'

'

Minimum current ratio

'

'

'

'

'

'

'

1

'

'

'

'

'

'

Line of credit facility, amount outstanding

'

'

'

'

60,000,000

'

'

'

'

'

'

'

'

'

Outstanding letters of credit

'

'

'

'

5,200,000

'

'

'

'

'

'

'

'

'

Line of credit facility, remaining borrowing capacity

'

'

'

'

1,434,800,000

'

'

'

'

'

'

'

'

'

Weighted average interest rate

'

'

'

'

1.70%

'

'

'

'

'

'

'

'

'

Deferred financing costs

40,300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Amortization of deferred financing costs

$1,600,000

$800,000

'

'

'

'

'

'

'

'

'

'

'

'

LongTerm_Debt_Schedule_of_Long

Long-Term Debt - Schedule of Long-Term Debt Interest Rate (Detail)	3 Months Ended
	Mar. 31, 2014
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, 2014
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]	'
Balance at December 31, 2013	$36,458
Liabilities incurred during period	1,401
Liabilities settled during period	-1,974	[1]
Accretion expense during period	445	[2]
Balance at March 31, 2014	$36,330
[1]	Liabilities settled during period represents ARO related to the properties sold in the Sanish Divestiture.
[2]	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, 2014
In Millions, unless otherwise specified
Asset Retirement Obligation Disclosure [Abstract]	'
Total asset retirement obligations, current portion	$0.50

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Stock-based compensation expense	$4,505	$2,289
Restricted Stock [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Award vesting period	'3 years	'
Restricted stock granted	588,660	'
Granted, weighted average grant date fair value per unit	$42.55	'
Stock-based compensation expense	3,900	2,100
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	12.70%	'
Performance Share Units [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Annual forfeiture rate	3.30%	'
Restricted stock granted	158,970	'
Granted, weighted average grant date fair value per unit	$41.71	'
Stock-based compensation expense	$600	$300
Right to received shares of common stock	1	'
Performance share units initial performance period, years	'3 years	'
Amortized performance period	'4 years	'
Number of trading days	'30 days	'
Valuation model standard deviation term	'2 years	'
Performance Share Units [Member] | Minimum [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
PSU granted percentage of earnings	0.00%	'
Performance Share Units [Member] | Maximum [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
PSU granted percentage of earnings	200.00%	'
PSU 2014 Grants [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Amortized performance period	'4 years	'
Expected percentage earned	98.00%	'

StockBased_Compensation_Summar

Stock-Based Compensation - Summary of Assumptions (Detail) (PSU 2014 Grants [Member])	3 Months Ended
	Mar. 31, 2014
PSU 2014 Grants [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Forecast period (years)	'4 years
Risk-free interest rate	1.12%
Oasis stock price volatility	44.49%

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Tax Disclosure [Abstract]	'	'
Effective tax rate	37.40%	37.50%

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, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]	'	'
Basic weighted average common shares outstanding	99,560	92,375
Dilution effect of stock awards at end of period	489	276
Diluted weighted average common shares outstanding	100,049	92,651
Anti-dilutive stock-based compensation awards	1,047	778

Earnings_Per_Share_Earnings_Pe

Earnings Per Share Earnings Per Share - Additional Information (Details) (USD $)	0 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 09, 2013	Mar. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]	'	'	'
Common stock, par value (in dollars per share)	'	$0.01	$0.01
Shares issued, price per share	$44.94	'	'
Proceeds from issuance of common stock, net of discounts and expenses	$314,400	'	'
Common Stock [Member]	'	'	'
Class of Stock [Line Items]	'	'	'
Issuance of common stock, shares	7,000,000	'	'
Common stock, par value (in dollars per share)	$0.01	'	'
Additional Paid-in-Capital [Member]	'	'	'
Class of Stock [Line Items]	'	'	'
Proceeds from issuance of common stock, net of discounts and expenses	314,300	'	'
Common Stock [Member]	'	'	'
Class of Stock [Line Items]	'	'	'
Proceeds from issuance of common stock, net of discounts and expenses	$70	'	'

Business_Segment_Information_A

Business Segment Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014
	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, 2014	Mar. 31, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]	'	'	'
Total revenues	$349,519	$248,304	'
Operating income (loss)	329,080	117,953	'
Other income (expense)	-57,608	-35,015	'
Income (loss) before income taxes	271,472	82,938	'
Total assets	4,792,084	'	4,711,924
Exploration and Production [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	331,847	241,652	'
Well Services [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	15,827	5,714	'
Midstream Services [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	1,845	938	'
Operating Segments [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	393,606	282,240	'
Operating income (loss)	329,080	117,953	'
Other income (expense)	-57,608	-35,015	'
Income (loss) before income taxes	271,472	82,938	'
Total assets	4,792,084	'	4,711,924
Operating Segments [Member] | Exploration and Production [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	331,847	241,652	'
Operating income (loss)	326,533	114,885	'
Other income (expense)	-57,660	-35,019	'
Income (loss) before income taxes	268,873	79,866	'
Total assets	4,603,244	'	4,532,264
Operating Segments [Member] | Well Services [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	52,406	35,768	'
Operating income (loss)	1,620	2,563	'
Other income (expense)	52	4	'
Income (loss) before income taxes	1,672	2,567	'
Total assets	76,929	'	70,708
Operating Segments [Member] | Midstream Services [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	9,353	4,820	'
Operating income (loss)	927	505	'
Income (loss) before income taxes	927	505	'
Total assets	111,911	'	108,952
Intersegment Eliminations [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	-44,087	-33,936	'
Intersegment Eliminations [Member] | Well Services [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	-36,579	-30,054	'
Intersegment Eliminations [Member] | Midstream Services [Member]	'	'	'
Segment Reporting Information [Line Items]	'	'	'
Total revenues	($7,508)	($3,882)	'

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
Commitments And Contingencies [Line Items]	'
Total rental commitments under leases	$10.40
Future obligations under water purchase agreements	5
Future obligations under cost sharing agreements	11.1
Investment commitment	6.9
Long Term Commitments [Member]	'
Commitments And Contingencies [Line Items]	'
Future obligations under supply agreements	43.7
Drilling contracts [Member]	'
Commitments And Contingencies [Line Items]	'
Payments upon early contract termination	$19.80
Williston Basin Project [Member] | Long Term Commitments [Member]	'
Commitments And Contingencies [Line Items]	'
Maximum commitment term	'5 years
Williston Basin Project [Member] | Long Term Commitments [Member] | Crude oil [Member]	'
Commitments And Contingencies [Line Items]	'
Minimum quantity of delivery	8,100,000
Williston Basin Project [Member] | Long Term Commitments [Member] | Natural Gas [Member]	'
Commitments And Contingencies [Line Items]	'
Minimum quantity of delivery	11,400

Condensed_Consolidating_Financ2

Condensed Consolidating Financial Information - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2014
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, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
ASSETS	'	'	'	'
Cash and cash equivalents	$56,298	$91,901	$165,989	$213,447
Accounts receivable — oil and gas revenues	202,749	175,653	'	'
Accounts receivable — joint interest partners	134,553	139,459	'	'
Accounts receivable – affiliates	'	'	'	'
Inventory	19,862	20,652	'	'
Prepaid expenses	24,450	10,191	'	'
Deferred income taxes	8,484	6,335	'	'
Derivative instruments	778	2,264	'	'
Advances to joint interest partners	214	760	'	'
Other current assets	420	391	'	'
Total current assets	447,808	447,606	'	'
Property, plant and equipment	'	'	'	'
Oil and gas properties (successful efforts method)	4,820,902	4,528,958	'	'
Other property and equipment	200,158	188,468	'	'
Less: accumulated depreciation, depletion, amortization and impairment	-723,429	-637,676	'	'
Total property, plant and equipment, net	4,297,631	4,079,750	'	'
Assets held for sale	0	137,066	'	'
Derivative instruments	470	1,333	'	'
Deferred income taxes	'	'	'	'
Deferred costs and other assets	46,175	46,169	'	'
Total assets	4,792,084	4,711,924	'	'
LIABILITIES AND STOCKHOLDERS’ EQUITY	'	'	'	'
Accounts payable	24,516	8,920	'	'
Accounts payable – affiliates	'	'	'	'
Revenues and production taxes payable	183,120	146,741	'	'
Accrued liabilities	283,024	241,830	'	'
Accrued interest payable	24,562	47,910	'	'
Derivative instruments	20,663	8,188	'	'
Advances from joint interest partners	10,931	12,829	'	'
Other current liabilities	2,766	0	'	'
Total current liabilities	549,582	466,418	'	'
Long-term debt	2,260,000	2,535,570	'	'
Deferred income taxes	424,049	323,147	'	'
Asset retirement obligations	35,790	35,918	'	'
Derivative instruments	679	139	'	'
Other liabilities	2,002	2,183	'	'
Total liabilities	3,272,102	3,363,375	'	'
Stockholders’ equity	'	'	'	'
Common stock, $0.01 par value: 300,000,000 shares authorized; 101,416,749 and 100,866,589 shares issued at March 31, 2014 and December 31, 2013, respectively	999	996	'	'
Treasury stock, at cost: 238,453 and 167,155 shares at March 31, 2014 and December 31, 2013, respectively	-8,387	-5,362	'	'
Additional paid-in capital	989,525	985,023	'	'
Retained earnings	537,845	367,892	'	'
Total stockholders’ equity	1,519,982	1,348,549	'	'
Total liabilities and stockholders’ equity	4,792,084	4,711,924	'	'
Parent/Issuer [Member]	'	'	'	'
ASSETS	'	'	'	'
Cash and cash equivalents	936	34,277	81,836	133,797
Accounts receivable – affiliates	770	770	'	'
Prepaid expenses	159	318	'	'
Other current assets	0	'	'	'
Total current assets	1,865	35,365	'	'
Property, plant and equipment	'	'	'	'
Investments in and advances to subsidiaries	3,621,362	3,450,668	'	'
Deferred income taxes	101,341	85,288	'	'
Deferred costs and other assets	32,862	33,983	'	'
Total assets	3,757,430	3,605,304	'	'
LIABILITIES AND STOCKHOLDERS’ EQUITY	'	'	'	'
Accounts payable	0	0	'	'
Accounts payable – affiliates	12,802	9,100	'	'
Accrued liabilities	119	33	'	'
Accrued interest payable	24,527	47,622	'	'
Total current liabilities	37,448	56,755	'	'
Long-term debt	2,200,000	2,200,000	'	'
Total liabilities	2,237,448	2,256,755	'	'
Stockholders’ equity	'	'	'	'
Common stock, $0.01 par value: 300,000,000 shares authorized; 101,416,749 and 100,866,589 shares issued at March 31, 2014 and December 31, 2013, respectively	999	996	'	'
Treasury stock, at cost: 238,453 and 167,155 shares at March 31, 2014 and December 31, 2013, respectively	-8,387	-5,362	'	'
Additional paid-in capital	989,525	985,023	'	'
Retained earnings	537,845	367,892	'	'
Total stockholders’ equity	1,519,982	1,348,549	'	'
Total liabilities and stockholders’ equity	3,757,430	3,605,304	'	'
Combined Guarantor Subsidiaries [Member]	'	'	'	'
ASSETS	'	'	'	'
Cash and cash equivalents	55,362	57,624	84,153	79,650
Accounts receivable — oil and gas revenues	202,749	175,653	'	'
Accounts receivable — joint interest partners	134,553	139,459	'	'
Accounts receivable – affiliates	12,802	9,100	'	'
Inventory	19,862	20,652	'	'
Prepaid expenses	24,291	9,873	'	'
Deferred income taxes	8,484	6,335	'	'
Derivative instruments	778	2,264	'	'
Advances to joint interest partners	214	760	'	'
Other current assets	420	391	'	'
Total current assets	459,515	422,111	'	'
Property, plant and equipment	'	'	'	'
Oil and gas properties (successful efforts method)	4,820,902	4,528,958	'	'
Other property and equipment	200,158	188,468	'	'
Less: accumulated depreciation, depletion, amortization and impairment	-723,429	-637,676	'	'
Total property, plant and equipment, net	4,297,631	4,079,750	'	'
Assets held for sale	'	137,066	'	'
Derivative instruments	470	1,333	'	'
Deferred costs and other assets	13,313	12,186	'	'
Total assets	4,770,929	4,652,446	'	'
LIABILITIES AND STOCKHOLDERS’ EQUITY	'	'	'	'
Accounts payable	24,516	8,920	'	'
Accounts payable – affiliates	770	770	'	'
Revenues and production taxes payable	183,120	146,741	'	'
Accrued liabilities	282,905	241,797	'	'
Accrued interest payable	35	288	'	'
Derivative instruments	20,663	8,188	'	'
Advances from joint interest partners	10,931	12,829	'	'
Other current liabilities	2,766	'	'	'
Total current liabilities	525,706	419,533	'	'
Long-term debt	60,000	335,570	'	'
Deferred income taxes	525,390	408,435	'	'
Asset retirement obligations	35,790	35,918	'	'
Derivative instruments	679	139	'	'
Other liabilities	2,002	2,183	'	'
Total liabilities	1,149,567	1,201,778	'	'
Stockholders’ equity	'	'	'	'
Capital contributions from affiliates	2,904,739	2,930,978	'	'
Additional paid-in capital	8,743	8,743	'	'
Retained earnings	707,880	510,947	'	'
Total stockholders’ equity	3,621,362	3,450,668	'	'
Total liabilities and stockholders’ equity	4,770,929	4,652,446	'	'
Intercompany Eliminations [Member]	'	'	'	'
ASSETS	'	'	'	'
Accounts receivable – affiliates	-13,572	-9,870	'	'
Total current assets	-13,572	-9,870	'	'
Property, plant and equipment	'	'	'	'
Investments in and advances to subsidiaries	-3,621,362	-3,450,668	'	'
Deferred income taxes	-101,341	-85,288	'	'
Total assets	-3,736,275	-3,545,826	'	'
LIABILITIES AND STOCKHOLDERS’ EQUITY	'	'	'	'
Accounts payable – affiliates	-13,572	-9,870	'	'
Total current liabilities	-13,572	-9,870	'	'
Deferred income taxes	-101,341	-85,288	'	'
Total liabilities	-114,913	-95,158	'	'
Stockholders’ equity	'	'	'	'
Capital contributions from affiliates	-2,904,739	-2,930,978	'	'
Additional paid-in capital	-8,743	-8,743	'	'
Retained earnings	-707,880	-510,947	'	'
Total stockholders’ equity	-3,621,362	-3,450,668	'	'
Total liabilities and stockholders’ equity	($3,736,275)	($3,545,826)	'	'

Condensed_Consolidating_Financ4

Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Balance Sheet (Parenthetical) (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
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	101,416,749	100,866,589
Treasury stock, shares	238,453	167,155

Condensed_Consolidating_Financ5

Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Statement of Operations (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Revenues	'	'
Oil and gas revenues	$331,847	$241,651
Well services and midstream revenues	17,672	6,653
Total revenues	349,519	248,304
Expenses	'	'
Lease operating expenses	39,989	19,489
Well services and midstream operating expenses	10,920	2,914
Marketing, transportation and gathering expenses	5,186	3,389
Production taxes	31,803	22,089
Depreciation, depletion and amortization	91,272	66,261
Exploration expenses	380	1,857
Impairment of oil and gas properties	762	498
General and administrative expenses	23,520	13,854
Total expenses	203,832	130,351
Gain on sale of properties	183,393	0
Operating income (loss)	329,080	117,953
Other income (expense)	'	'
Net loss on derivative instruments	-17,603	-14,612
Interest expense, net of capitalized interest	-40,158	-21,183
Other income (expense)	153	780
Total other income (expense)	-57,608	-35,015
Income before income taxes	271,472	82,938
Income tax benefit (expense)	-101,519	-31,087
Net income	169,953	51,851
Parent/Issuer [Member]	'	'
Expenses	'	'
General and administrative expenses	5,612	2,876
Total expenses	5,612	2,876
Operating income (loss)	-5,612	-2,876
Other income (expense)	'	'
Equity in earnings in subsidiaries	196,933	66,243
Interest expense, net of capitalized interest	-37,424	-20,518
Other income (expense)	3	376
Total other income (expense)	159,512	46,101
Income before income taxes	153,900	43,225
Income tax benefit (expense)	16,053	8,626
Net income	169,953	51,851
Combined Guarantor Subsidiaries [Member]	'	'
Revenues	'	'
Oil and gas revenues	331,847	241,651
Well services and midstream revenues	17,672	6,653
Total revenues	349,519	248,304
Expenses	'	'
Lease operating expenses	39,989	19,489
Well services and midstream operating expenses	10,920	2,914
Marketing, transportation and gathering expenses	5,186	3,389
Production taxes	31,803	22,089
Depreciation, depletion and amortization	91,272	66,261
Exploration expenses	380	1,857
Impairment of oil and gas properties	762	498
General and administrative expenses	17,908	10,978
Total expenses	198,220	127,475
Gain on sale of properties	183,393	'
Operating income (loss)	334,692	120,829
Other income (expense)	'	'
Net loss on derivative instruments	-17,603	-14,612
Interest expense, net of capitalized interest	-2,734	-665
Other income (expense)	150	404
Total other income (expense)	-20,187	-14,873
Income before income taxes	314,505	105,956
Income tax benefit (expense)	-117,572	-39,713
Net income	196,933	66,243
Intercompany Eliminations [Member]	'	'
Other income (expense)	'	'
Equity in earnings in subsidiaries	-196,933	-66,243
Total other income (expense)	-196,933	-66,243
Income before income taxes	-196,933	-66,243
Net income	($196,933)	($66,243)

Condensed_Consolidating_Financ6

Condensed Consolidating Financial Information - Schedule of Condensed Consolidating Statement of Cash Flows (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:	'	'
Net income	$169,953	$51,851
Adjustments to reconcile net income to net cash provided by (used in) operating activities:	'	'
Depreciation, depletion and amortization	91,272	66,261
Gain on sale of properties	-183,393	0
Impairment of oil and gas properties	762	498
Deferred income taxes	98,753	30,987
Derivative instruments	17,603	14,612
Stock-based compensation expenses	4,505	2,289
Debt discount amortization and other	1,487	746
Working capital and other changes:	'	'
Change in accounts receivable	-9,275	-3,360
Change in inventory	790	-8,407
Change in prepaid expenses	-14,259	293
Change in other current assets	-29	-232
Change in other assets	-1,593	0
Change in accounts payable and accrued liabilities	29,007	15,009
Change in other current liabilities	2,766	0
Change in other liabilities	-82	0
Net cash provided by operating activities	208,267	170,547
Cash flows from investing activities:	'	'
Capital expenditures	-280,895	-217,819
Proceeds from sale of properties	321,943	0
Costs related to sale of properties	-2,010	0
Derivative settlements	-2,239	1,686
Advances from joint interest partners	-1,898	-1,691
Net cash provided by (used in) investing activities	34,901	-217,824
Cash flows from financing activities:	'	'
Principal payments on revolving credit facility	-275,570	0
Purchases of treasury stock	-3,025	-156
Debt issuance costs	0	-25
Other	-176	0
Net cash used in financing activities	-278,771	-181
Decrease in cash and cash equivalents	-35,603	-47,458
Beginning of period	91,901	213,447
End of period	56,298	165,989
Parent/Issuer [Member]	'	'
Cash flows from operating activities:	'	'
Net income	169,953	51,851
Adjustments to reconcile net income to net cash provided by (used in) operating activities:	'	'
Equity in earnings of subsidiaries	-196,933	-66,243
Deferred income taxes	-16,053	-8,626
Stock-based compensation expenses	4,428	2,278
Debt discount amortization and other	1,123	644
Working capital and other changes:	'	'
Change in accounts receivable	0	11
Change in prepaid expenses	159	157
Change in other current assets	0	-339
Change in accounts payable and accrued liabilities	-19,307	-8,286
Net cash provided by operating activities	-56,630	-28,553
Cash flows from investing activities:	'	'
Net cash provided by (used in) investing activities	0	'
Cash flows from financing activities:	'	'
Purchases of treasury stock	-3,025	-156
Investment in / capital contributions from affiliates	26,490	-23,252
Other	-176	'
Net cash used in financing activities	23,289	-23,408
Decrease in cash and cash equivalents	-33,341	-51,961
Beginning of period	34,277	133,797
End of period	936	81,836
Combined Guarantor Subsidiaries [Member]	'	'
Cash flows from operating activities:	'	'
Net income	196,933	66,243
Adjustments to reconcile net income to net cash provided by (used in) operating activities:	'	'
Depreciation, depletion and amortization	91,272	66,261
Gain on sale of properties	-183,393	'
Impairment of oil and gas properties	762	498
Deferred income taxes	114,806	39,613
Derivative instruments	17,603	14,612
Stock-based compensation expenses	77	11
Debt discount amortization and other	364	102
Working capital and other changes:	'	'
Change in accounts receivable	-12,977	-3,740
Change in inventory	790	-8,407
Change in prepaid expenses	-14,418	136
Change in other current assets	-29	107
Change in other assets	-1,593	'
Change in accounts payable and accrued liabilities	52,016	23,664
Change in other current liabilities	2,766	'
Change in other liabilities	-82	'
Net cash provided by operating activities	264,897	199,100
Cash flows from investing activities:	'	'
Capital expenditures	-280,895	-217,819
Proceeds from sale of properties	321,943	'
Costs related to sale of properties	-2,010	'
Derivative settlements	-2,239	1,686
Advances from joint interest partners	-1,898	-1,691
Net cash provided by (used in) investing activities	34,901	-217,824
Cash flows from financing activities:	'	'
Principal payments on revolving credit facility	-275,570	'
Debt issuance costs	'	-25
Investment in / capital contributions from affiliates	-26,490	23,252
Net cash used in financing activities	-302,060	23,227
Decrease in cash and cash equivalents	-2,262	4,503
Beginning of period	57,624	79,650
End of period	55,362	84,153
Intercompany Eliminations [Member]	'	'
Cash flows from operating activities:	'	'
Net income	-196,933	-66,243
Adjustments to reconcile net income to net cash provided by (used in) operating activities:	'	'
Equity in earnings of subsidiaries	196,933	66,243
Working capital and other changes:	'	'
Change in accounts receivable	3,702	369
Change in accounts payable and accrued liabilities	($3,702)	($369)

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (USD $)	Mar. 31, 2014	Mar. 31, 2014	7-May-14	7-May-14	Apr. 30, 2014
In Millions, unless otherwise specified		Drilling contracts [Member]	Subsequent Event [Member]	Subsequent Event [Member]	Two Thousand Fifteen Swap Agreement [Member]
				Drilling contracts [Member]	Subsequent Event [Member]
					bbl
Subsequent Event [Line Items]	'	'	'	'	'
Total rental commitments under leases	$10.40	'	$27.60	'	'
Payments upon early contract termination	'	$19.80	'	$21.90	'
Total Notional Amount of Oil (Barrels)	'	'	'	'	1,092,000