Concho Resources (CXO) 10-K 26 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 24, 2015
Document Documentand Entity Information [Abstract]
Document Type	10-K
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	CXO
Entity Registrant Name	CONCHO RESOURCES INC
Entity Central Index Key	1358071
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		113,101,342
Entity Public Float	$16,062,966,367

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$21,000	$21,000
Accounts receivable, net of allowance for doubtful accounts:
Oil and natural gas	250,600,000	223,790,000
Joint operations and other	409,665,000	247,945,000
Derivative instruments	490,351,000	590,000
Deferred income taxes	0	30,069,000
Prepaid costs and other	37,759,000	18,460,000
Total current assets	1,188,396,000	520,875,000
Property and equipment:
Oil and natural gas properties, successful efforts method	13,867,831,000	11,215,373,000
Accumulated depletion and depreciation	-3,790,953,000	-2,384,108,000
Total oil and natural gas properties, net	10,076,878,000	8,831,265,000
Other property and equipment, net	129,136,000	114,783,000
Total property and equipment, net	10,206,014,000	8,946,048,000
Deferred loan costs, net	68,443,000	73,048,000
Intangible asset - operating rights, net	27,154,000	28,615,000
Inventory	14,435,000	19,682,000
Noncurrent derivative instruments	262,349,000	966,000
Other assets	33,172,000	1,930,000
Total assets	11,799,963,000	9,591,164,000
Accounts payable:
Trade	20,380,000	13,936,000
Related parties	0	0
Bank overdrafts	92,541,000	36,718,000
Revenue payable	238,098,000	177,617,000
Accrued and prepaid drilling costs	718,300,000	318,296,000
Derivative instruments	0	53,701,000
Deferred income taxes	162,566,000	0
Other current liabilities	195,308,000	156,600,000
Total current liabilities	1,427,193,000	756,868,000
Long-term debt	3,517,320,000	3,630,421,000
Deferred income taxes	1,438,185,000	1,334,653,000
Noncurrent derivative instruments	0	14,088,000
Asset retirement obligations and other long-term liabilities	136,477,000	97,185,000
Commitments and contingencies (Note 9)
Stockholders' equity:
Common stock, $0.001 par value; 300,000,000 authorized; 113,264,918 and 105,222,765 shares issued at December 31, 2014 and 2013, respectively	113,000	105,000
Additional paid-in capital	3,027,412,000	2,027,162,000
Retained earnings	2,279,741,000	1,741,566,000
Treasury stock, at cost; 260,124 and 127,305 shares at December 31, 2014 and 2013, respectively	-26,478,000	-10,884,000
Total stockholders' equity	5,280,788,000	3,757,949,000
Total liabilities and stockholders' equity	$11,799,963,000	$9,591,164,000

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	113,264,918	105,222,765

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating revenues:
Oil sales	$2,189,072	$1,938,433	$1,482,998
Natural gas sales	471,075	381,486	336,816
Total operating revenues	2,660,147	2,319,919	1,819,814
Operating costs and expenses:
Oil and natural gas production	538,374	455,436	343,743
Exploration and abandonments	284,821	109,549	39,840
Depreciation, depletion and amortization	979,740	772,608	575,128
Accretion of discount on asset retirement obligations	7,072	6,047	4,187
Impairments of long-lived assets	447,151	65,375	0
General and administrative (including non-cash stock-based compensation of $47,130, $35,078 and $29,872 for the years ended December 31, 2014, 2013 and 2012, respectively)	204,161	169,815	133,796
(Gain) loss on derivatives not designated as hedges	-890,917	123,652	-127,443
Total operating costs and expenses	1,570,402	1,702,482	969,251
Income from operations	1,089,745	617,437	850,563
Other income (expense):
Interest expense	-216,661	-218,581	-182,705
Loss on extinguishment of debt	-4,316	-28,616	0
Other, net	-12,808	-13,081	-8,587
Total other expense	-233,785	-260,278	-191,292
Income from continuing operations before income taxes	855,960	357,159	659,271
Income tax expense	-317,785	-118,237	-251,041
Income from continuing operations	538,175	238,922	408,230
Income from discontinued operations, net of tax	0	12,081	23,459
Net income	$538,175	$251,003	$431,689
Basic earnings per share:
Income from continuing operations	$4.89	$2.28	$3.96
Income from discontinued operations, net of tax	$0	$0.11	$0.22
Net income	$4.89	$2.39	$4.18
Diluted earnings per share:
Income from continuing operations	$4.88	$2.28	$3.93
Income from discontinued operations, net of tax	$0	$0.11	$0.22
Net income	$4.88	$2.39	$4.15

Consolidated_Statements_of_Ope1

Consolidated Statements of Operations (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Non-cash stock-based compensation	$47,130	$35,078	$29,872

Consolidated_Statement_of_Stoc

Consolidated Statement of Stockholders Equity (USD $)	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
BALANCE at Dec. 31, 2011	$2,980,739,000	$104,000	$1,925,757,000	$1,058,874,000	($3,996,000)
BALANCE, Shares at Dec. 31, 2011		103,756,000			56,000
Net income	431,689,000	0	0	431,689,000	0
Stock options exercised	8,123,000	1,000	8,122,000	0	0
Stock options exercised, shares	500,299	500,000			0
Grants of restricted stock, shares	470,633	471,000
Cancellation of restricted stock, shares		-59,000			0
Stock-based compensation	29,872,000	0	29,872,000	0	0
Excess tax benefits related to stock-based compensation	18,963,000	0	18,963,000	0	0
Purchase of treasury stock	-3,190,000	0	0	0	-3,190,000
Purchase of treasury stock, shares		0			31,000
BALANCE at Dec. 31, 2012	3,466,196,000	105,000	1,982,714,000	1,490,563,000	-7,186,000
BALANCE, Shares at Dec. 31, 2012		104,668,000			87,000
Net income	251,003,000	0	0	251,003,000	0
Stock options exercised	3,223,000	0	3,223,000	0	0
Stock options exercised, shares	174,342	174,000			0
Grants of restricted stock, shares	498,468	499,000
Cancellation of restricted stock, shares		-118,000			0
Stock-based compensation	35,078,000	0	35,078,000	0	0
Excess tax benefits related to stock-based compensation	6,147,000	0	6,147,000	0	0
Purchase of treasury stock	-3,698,000	0	0	0	-3,698,000
Purchase of treasury stock, shares		0			40,000
BALANCE at Dec. 31, 2013	3,757,949,000	105,000	2,027,162,000	1,741,566,000	-10,884,000
BALANCE, Shares at Dec. 31, 2013		105,223,000			127,000
Net income	538,175,000	0	0	538,175,000	0
Issuance of common stock (Shares)		7,475,000
Issuance of common stock	931,989,000	7,000	931,982,000
Stock options exercised	4,659,000	1,000	4,658,000	0	0
Stock options exercised, shares	207,824	208,000			0
Grants of restricted stock, shares	448,730	448,000			0
Cancellation of restricted stock, shares		-89,000			0
Stock-based compensation	47,130,000	0	47,130,000	0	0
Excess tax benefits related to stock-based compensation	16,480,000	0	16,480,000	0	0
Purchase of treasury stock	-15,594,000	0	0	0	-15,594,000
Purchase of treasury stock, shares		0			133,000
BALANCE at Dec. 31, 2014	$5,280,788,000	$113,000	$3,027,412,000	$2,279,741,000	($26,478,000)
BALANCE, Shares at Dec. 31, 2014		113,265,000			260,000

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$538,175,000	$251,003,000	$431,689,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	979,740,000	772,608,000	575,128,000
Accretion of discount on asset retirement obligations	7,072,000	6,047,000	4,187,000
Impairments of long-lived assets	447,151,000	65,375,000	0
Exploration and abandonments, including dry holes	265,064,000	80,714,000	19,913,000
Non-cash compensation expense	47,130,000	35,078,000	29,872,000
Deferred income taxes	296,167,000	102,427,000	241,819,000
Loss on disposition of assets, net	9,308,000	1,268,000	372,000
(Gain) loss on derivatives not designated as hedges	-890,917,000	123,652,000	-127,443,000
Discontinued operations	0	-12,250,000	49,011,000
Other non-cash items	18,379,000	19,720,000	12,420,000
Changes in operating assets and liabilities, net of acquisitions and dispositions:
Accounts receivable	-104,988,000	-40,009,000	-23,091,000
Prepaid costs and other	-23,628,000	4,945,000	-8,200,000
Inventory	2,441,000	509,000	-1,587,000
Accounts payable	1,566,000	-18,469,000	4,165,000
Revenue payable	60,481,000	28,593,000	16,012,000
Other current liabilities	20,646,000	-59,191,000	13,211,000
Net cash provided by operating activities	1,673,787,000	1,362,020,000	1,237,478,000
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures on oil and natural gas properties	-2,554,914,000	-1,850,992,000	-2,717,283,000
Additions to other property and equipment	-34,320,000	-28,678,000	-56,588,000
Proceeds from the disposition of assets	1,305,000	15,217,000	492,497,000
Contributions to equity method investment	30,050,000	0	0
Funds held in escrow	0	0	17,394,000
Settlements received from (paid on) derivatives not designated as hedges	71,983,000	-32,341,000	23,536,000
Net cash used in investing activities	-2,545,996,000	-1,896,794,000	-2,240,444,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of debt	2,081,000,000	3,257,575,000	4,262,000,000
Payments of debt	-2,191,500,000	-2,729,700,000	-3,241,500,000
Exercise of stock options	4,659,000	3,223,000	8,123,000
Excess tax benefit from stock-based compensation	16,480,000	6,147,000	18,963,000
Net proceeds from issuance of common stock	931,989,000	0	0
Payments for loan costs	-10,648,000	-14,075,000	-23,926,000
Purchase of treasury stock	-15,594,000	-3,698,000	-3,190,000
Bank overdrafts	55,823,000	12,443,000	-14,966,000
Net cash provided by financing activities	872,209,000	531,915,000	1,005,504,000
Net increase (decrease) in cash and cash equivalents	0	-2,859,000	2,538,000
Cash and cash equivalents at beginning of period	21,000	2,880,000	342,000
Cash and cash equivalents at end of period	21,000	21,000	2,880,000
SUPPLEMENTAL CASH FLOWS:
Cash paid for interest	211,342,000	200,961,000	158,715,000
Cash paid for income taxes	$27,844,000	$21,376,000	$19,674,000

Organization_and_nature_of_ope

Organization and nature of operations	12 Months Ended
	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and nature of operations	Note 1. Organization and nature of operations
	Concho Resources Inc. (the “Company”) is a Delaware corporation formed on February 22, 2006. The Company’s principal business is the acquisition, development and exploration of oil and natural gas properties primarily located in the Permian Basin region of Southeast New Mexico and West Texas.

Summary_of_significant_account

Summary of significant accounting policies	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Summary of significant accounting policies	Note 2. Summary of significant accounting policies
	Principles of consolidation. The consolidated financial statements of the Company include the accounts of the Company and its 100 percent owned subsidiaries. In addition, from time to time, a third-party has formed entities to effectuate a tax-free exchange of assets for the Company. The Company has 100 percent control over the decisions of the entities, but has no direct ownership. The third-party conveys ownership to the Company upon completion of the tax-free exchange process. The Company consolidates the financial statements of these entities. All material intercompany balances and transactions have been eliminated.
	Discontinued operations. The Company made the following divestiture of assets during the period covered by these consolidated financial statements:
	(dollars in millions)
	Date divested					Dec-12
	Net proceeds				$	503.1
	Gain on disposition of assets				$	0.9
	As a result, the Company has reflected the results of operations of these divested assets as discontinued operations, rather than as a component of continuing operations. See Note 13 for additional information regarding this divestiture and its discontinued operations.
	Use of estimates in the preparation of financial statements. Preparation of financial statements in conformity with generally accepted accounting principles in the United States of America (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from these estimates. Depletion of oil and natural gas properties is determined using estimates of proved oil and natural gas reserves. There are numerous uncertainties inherent in the estimation of quantities of proved reserves and in the projection of future rates of production and the timing of development expenditures. Similarly, evaluations for impairment of proved and unproved oil and natural gas properties are subject to numerous uncertainties including, among others, estimates of future recoverable reserves and commodity price outlooks. Other significant estimates include, but are not limited to, the asset retirement obligations, fair value of derivative financial instruments, the fair value of business combinations, fair value of stock-based compensation and income taxes.
	Cash equivalents. The Company considers all cash on hand, depository accounts held by banks, money market accounts and investments with an original maturity of three months or less to be cash equivalents. The Company’s cash and cash equivalents are held in financial institutions in amounts that exceed the insurance limits of the Federal Deposit Insurance Corporation. However, management believes that the Company’s counterparty risks are minimal based on the reputation and history of the institutions selected.
	Accounts receivable. The Company sells oil and natural gas to various customers and participates with other parties in the drilling, completion and operation of oil and natural gas wells. Joint interest and oil and natural gas sales receivables related to these operations are generally unsecured. The Company determines joint interest operations accounts receivable allowances based on management’s assessment of the creditworthiness of the joint interest owners and the Company’s ability to realize the receivables through netting of anticipated future production revenues. Receivables are considered past due if full payment is not received by the contractual due date. Past due accounts are generally written off against the allowance for doubtful accounts only after all collection attempts have been exhausted. The Company had an allowance for doubtful accounts of approximately $0.7 million at both December 31, 2014 and 2013.
	Inventory. Inventory consists primarily of tubular goods and other oilfield equipment that the Company plans to utilize in its ongoing exploration and development activities and is carried at the lower of cost or market value, on a weighted average cost basis.
	Deferred loan costs. Deferred loan costs are stated at cost, net of amortization, which is computed using the effective interest and straight-line methods. The Company had deferred loan costs of $68.4 million and $73.0 million, net of accumulated amortization of $59.7 million and $48.7 million, at December 31, 2014 and December 31, 2013, respectively.
	Oil and natural gas properties. The Company utilizes the successful efforts method of accounting for its oil and natural gas properties. Under this method all costs associated with productive wells and nonproductive development wells are capitalized, while nonproductive exploration costs are expensed. Capitalized acquisition costs relating to proved properties are depleted using the unit-of-production method based on proved reserves. The depletion of capitalized drilling and development costs is based on the unit-of-production method using proved developed reserves. During the years ended December 31, 2014, 2013 and 2012, the Company recognized depletion expense from continuing and discontinued operations of $960.9 million, $756.0 million and $591.3 million, respectively.
	The Company generally does not carry the costs of drilling an exploratory well as an asset in its consolidated balance sheets following the completion of drilling unless the exploratory well finds oil and natural gas reserves in an area requiring a major capital expenditure and both of the following conditions are met:
	the well has found a sufficient quantity of reserves to justify its completion as a producing well; and
	the Company is making sufficient progress assessing the reserves and the economic and operating viability of the project.
	Due to the capital intensive nature and the geographical location of certain projects, it may take the Company longer than one year to evaluate the future potential of the exploration well and economics associated with making a determination on its commercial viability. In these instances, the project's feasibility is not contingent upon price improvements or advances in technology, but rather the Company's ongoing efforts and expenditures related to accurately predicting the hydrocarbon recoverability based on well information, gaining access to other companies' production, transportation or processing facilities and/or getting partner approval to drill additional appraisal wells. These activities are ongoing and being pursued constantly. Consequently, the Company's assessment of suspended exploratory well costs is continuous until a decision can be made that the well has found proved reserves or is noncommercial and is charged to exploration and abandonments expense. See Note 3 for additional information regarding the Company's suspended exploratory well costs.
	Proceeds from the sales of individual properties and the capitalized costs of individual properties sold or abandoned are credited and charged, respectively, to accumulated depletion. Generally, no gain or loss is recognized until the entire depletion base is sold. However, gain or loss is recognized from the sale of less than an entire depletion base if the disposition is significant enough to materially impact the depletion rate of the remaining properties in the depletion base. Ordinary maintenance and repair costs are expensed as incurred.
	Costs of significant nonproducing properties, wells in the process of being drilled and completed and development projects are excluded from depletion until the related project is completed and proved developed reserves are established or, if unsuccessful, impairment is determined. The Company capitalizes interest, if debt is outstanding, on expenditures for significant development projects until such projects are ready for their intended use. The Company had capitalized interest of $1.4 million during 2014. The Company did not capitalize interest during 2013 or 2012.
	The Company reviews its long-lived assets to be held and used, including proved oil and natural gas properties, whenever events or circumstances indicate that the carrying value of those assets may not be recoverable. An impairment loss is indicated if the sum of the expected future cash flows is less than the carrying amount of the assets. In this circumstance, the Company recognizes an impairment loss for the amount by which the carrying amount of the asset exceeds the estimated fair value of the asset. The Company reviews its oil and natural gas properties by depletion base or by individual well for those wells not constituting part of a depletion base. For each property determined to be impaired, an impairment loss equal to the difference between the carrying value of the properties and the estimated fair value (discounted future cash flows) of the properties would be recognized at that time. Estimating future cash flows involves the use of judgments, including estimation of the proved and risk-adjusted unproved oil and natural gas reserve quantities, timing of development and production, expected future commodity prices, capital expenditures and production costs. The Company recognized impairment expense of $447.2 million and $65.4 million during the years ended December 31, 2014 and 2013, respectively, related to its proved oil and natural gas properties. The Company did not recognize impairment expense related to its long-lived assets for the year ended December 31, 2012.
	Unproved oil and natural gas properties are each periodically assessed for impairment by considering future drilling plans, the results of exploration activities, commodity price outlooks, planned future sales or expiration of all or a portion of such projects. During the years ended December 31, 2014, 2013 and 2012, the Company recognized expense of $217.3 million, $49.8 million and $12.4 million, respectively, related to abandoned prospects and expiring acreage, which is included in exploration and abandonments expense in the accompanying consolidated statements of operations.
	Other property and equipment.  Other capital assets include buildings, transportation equipment, computer equipment and software, telecommunications equipment, leasehold improvements and furniture and fixtures. These items are recorded at cost, or fair value if acquired, and are depreciated using the straight-line method based on expected lives of the individual assets or group of assets ranging from two to 31 years. The Company had other capital assets of $129.1 million and $114.8 million, net of accumulated depreciation of $52.5 million and $39.2 million, at December 31, 2014 and December 31, 2013, respectively. During the years ended December 31, 2014, 2013 and 2012, the Company recognized depreciation expense of $17.3 million, $15.2 million and $12.4 million, respectively.
	Intangible assets. The Company has capitalized certain operating rights acquired in an acquisition. The gross operating rights, which have no residual value, are amortized over the estimated economic life of 25 years. Impairment will be assessed if indicators of potential impairment exist or when there is a material change in the remaining useful economic life. The following table reflects the gross and net intangible assets at December 31, 2014 and 2013, respectively:
				December 31,
	(in thousands)			2014			2013
	Gross intangible - operating rights		$	36,557		$	36,557
	Accumulated amortization			-9,403			-7,942
		Net intangible - operating rights	$	27,154		$	28,615
	The following table reflects amortization expense from continuing and discontinued operations for the years ended December 31, 2014, 2013 and 2012:
			Years Ending December 31,
	(in thousands)		2014			2013		2012
	Amortization expense		$	1,461		$	1,461	$	1,549
	The following table reflects the estimated aggregate amortization expense for each of the periods presented below at December 31, 2014:
	(in thousands)
	2015		$	1,461
	2016			1,461
	2017			1,461
	2018			1,461
	2019			1,461
	Thereafter			19,849
		Total	$	27,154
	Equity method investment. The Company owns a 50 percent member interest in a midstream joint venture, Alpha Crude Connector, LLC (“ACC”), to construct a crude oil gathering and transportation system in the northern Delaware Basin. The Company accounts for its investment in ACC under the equity method of accounting for investments in unconsolidated affiliates. The Company’s net investment in ACC is $29.5 million at December 31, 2014 and is included in other assets in the Company’s consolidated balance sheet. The equity loss for the period since inception is approximately $1.3 million and is included in other expense in the Company’s consolidated statement of operations. During 2014, the Company recorded $0.7 million of capitalized interest on the investment in ACC.
	Environmental. The Company is subject to extensive federal, state and local environmental laws and regulations. These laws, which are often changing, regulate the discharge of materials into the environment and may require the Company to remove or mitigate the environmental effects of the disposal or release of petroleum or chemical substances at various sites. Environmental expenditures are expensed. Expenditures that relate to an existing condition caused by past operations and that have no future economic benefits are expensed. Liabilities for expenditures of a noncapital nature are recorded when environmental assessment and/or remediation is probable and the costs can be reasonably estimated. Such liabilities are generally undiscounted unless the timing of cash payments is fixed and readily determinable. At December 31, 2014 and 2013, the Company has accrued approximately $1.7 million and $2.3 million, respectively, related to environmental liabilities. During the years ended December 31, 2014, 2013 and 2012, the Company recognized environmental charges of $4.0 million, $3.4 million and $4.4 million, respectively.
	Derivative instruments. The Company recognizes its derivative instruments, other than any commodity derivative contracts that are designated as normal purchase and normal sale, as either assets or liabilities measured at fair value. The Company netted the fair value of derivative instruments by counterparty in the accompanying consolidated balance sheets where the right of offset exists. The Company did not have any derivatives designated as fair value or cash flow hedges during the years ended December 31, 2014, 2013 or 2012. The Company may also enter into physical delivery contracts to effectively provide commodity price hedges. Because these contracts are not expected to be net cash settled, they are considered to be normal sales contracts and not derivatives. Therefore, these contracts are not recorded in the Company’s consolidated financial statements.
	Asset retirement obligations. The Company records the fair value of a liability for an asset retirement obligation in the period in which it is incurred and a corresponding increase in the carrying amount of the related long-lived asset. Subsequently, the asset retirement cost included in the carrying amount of the related asset is allocated to expense through depletion of the asset. Changes in the liability due to passage of time are generally recognized as an increase in the carrying amount of the liability and as corresponding accretion expense.
	Treasury stock. Treasury stock purchases are recorded at cost. Upon reissuance, the cost of treasury shares held is reduced by the average purchase price per share of the aggregate treasury shares held.
	Revenue recognition. Oil and natural gas revenues are recorded at the time of physical transfer of such products to the purchaser, which for the Company is primarily at the wellhead. The Company follows the sales method of accounting for oil and natural gas sales, recognizing revenues based on the Company’s actual proceeds from the oil and natural gas sold to purchasers.
	Oil and natural gas imbalances. Oil and natural gas imbalances are generated on properties for which two or more owners have the right to take production “in-kind” and, in doing so, take more or less than their respective entitled percentage. Imbalances are tracked by well, but the Company does not record any receivable from or payable to the other owners unless the imbalance has reached a level at which it exceeds the remaining reserves in the respective well. If reserves are insufficient to offset the imbalance and the Company is in an overtake position, a liability is recorded for the amount of shortfall in reserves valued at a contract price or the market price in effect at the time the imbalance is generated. If the Company is in an undertake position, a receivable is recorded for an amount that is reasonably expected to be received, not to exceed the current market value of such imbalance. The Company had no significant imbalances at December 31, 2014 or 2013.
	General and administrative expense. The Company receives fees for the operation of jointly-owned oil and natural gas properties and records such reimbursements as reductions of general and administrative expense. Such fees from continuing and discontinued operations totaled approximately $23.2 million, $18.5 million and $16.8 million for the years ended December 31, 2014, 2013 and 2012, respectively.
	Stock-based compensation. For stock-based compensation awards granted, stock-based compensation expense is being recognized in the Company's financial statements on an accelerated basis over the awards' vesting periods based on their fair values on the dates of grant. The stock-based compensation awards generally vest over a period ranging from one to five years. The Company utilizes (i) the Black-Scholes option pricing model to measure the fair value of stock options, (ii) the average of the grant date’s high and low stock prices for the fair value of restricted stock and (iii) the Monte Carlo simulation method for the fair value of performance unit awards.
	Income taxes. The Company recognizes deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rate is recognized in income in the period that includes the enactment date. A valuation allowance is established to reduce deferred tax assets if it is more likely than not that the related tax benefits will not be realized.
	The Company evaluates uncertain tax positions for recognition and measurement in the consolidated financial statements. To recognize a tax position, the Company determines whether it is more likely than not that the tax positions will be sustained upon examination, including resolution of any related appeals or litigation, based on the technical merits of the position. A tax position that meets the more likely than not threshold is measured to determine the amount of benefit to be recognized in the consolidated financial statements. The amount of tax benefit recognized with respect to any tax position is measured as the largest amount of benefit that is greater than 50 percent likely of being realized upon settlement. The Company had no material uncertain tax positions that required recognition in the consolidated financial statements at December 31, 2014 and 2013. Any interest or penalties would be recognized as a component of income tax expense.
	Recent accounting pronouncements. In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” that outlines a new, single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. This new revenue recognition model provides a five-step analysis in determining when and how revenue is recognized. The new model will require revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration a company expects to receive in exchange for those goods or services.
	An entity is required to apply ASU 2014-09 for annual reporting periods beginning after December 15, 2016, and interim periods within those annual periods. An entity can apply ASU 2014-09 using either a full retrospective method, meaning the standard is applied to all of the periods presented, or a modified retrospective method, meaning the cumulative effect of initially applying the standard is recognized in the most current period presented in the financial statements. The Company is evaluating the impact that this new guidance will have on its consolidated financial statements.
	In April 2014, the FASB issued ASU No. 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity (Topics 205 and 360),” that raises the threshold for a disposal to qualify as a discontinued operation and requires new disclosures of both discontinued operations and certain other disposals that do not meet the definition of a discontinued operation. Under the revised standard, a discontinued operation is (i) a component of an entity or group of components that has been disposed of by sale, disposed of other than by sale or is classified as held for sale that represents a strategic shift that has or will have a major effect on an entity’s operations and financial results or (ii) an acquired business or nonprofit activity that is classified as held for sale on the date of the acquisition. This update is aimed at reducing the frequency of disposals reported as discontinued operations by focusing on strategic shifts that have or will have a major effect on an entity’s operations and financial results.
	An entity is required to apply ASU 2014-08 for annual reporting periods beginning on or after December 15, 2014, and interim periods within those annual periods, though earlier adoption is permitted. An entity should provide the disclosures required by this amendment prospectively. The Company does not expect this guidance to have a significant impact on the consolidated financial statements.

Exploratory_well_costs

Exploratory well costs	12 Months Ended
	Dec. 31, 2014
Disclosure Exploratory Well Costs Capitalized Exploratory Well Activity [Abstract]
Exploratory well costs	Note 3. Exploratory well costs
	The Company capitalizes exploratory well costs until a determination is made that the well has either found proved reserves or that it is impaired. The capitalized exploratory well costs are carried in unproved oil and natural gas properties. See Unaudited Supplementary Data for the proved and unproved components of oil and natural gas properties. If the exploratory well is determined to be impaired, the well costs are charged to exploration and abandonments expense in the consolidated statements of operations.
	The following table reflects the Company’s net capitalized exploratory well activity during each of the years ended December 31, 2014, 2013 and 2012:
			Years Ended December 31,
	(in thousands)		2014		2013		2012
	Beginning capitalized exploratory well costs		$	144,504	$	118,806	$	107,767
		Additions to exploratory well costs pending the determination of proved reserves		234,057		130,967		112,529
		Reclassifications due to determination of proved reserves		-99,657		-94,114		-99,514
		Exploratory well costs charged to expense		-37,247		-11,155		-1,976
	Ending capitalized exploratory well costs		$	241,657	$	144,504	$	118,806
	The following table provides an aging at December 31, 2014 and 2013 of capitalized exploratory well costs based on the date drilling was completed:
				December 31,
	(dollars in thousands)			2014		2013
	Capitalized exploratory well costs that have been capitalized for a period of one year or less		$	232,346	$	122,753
	Capitalized exploratory well costs that have been capitalized for a period greater than one year			9,311		21,751
		Total capitalized exploratory well costs	$	241,657	$	144,504
	Number of projects with exploratory well costs that have been capitalized for a period greater
		than one year		7		10
	Projects operated by others. At December 31, 2014, the Company had approximately $6.3 million of suspended well costs greater than one year recorded for five wells that are operated by others and waiting on completion.
	Other projects. At December 31, 2014, the Company had approximately $3.0 million of suspended well costs greater than one year recorded for two wells that have encountered technical difficulties that the Company is in the process of redrilling.

Asset_retirement_obligations

Asset retirement obligations	12 Months Ended
	Dec. 31, 2014
Asset Retirement Obligation Disclosure [Abstract]
Asset retirement obligations	Note 4. Asset retirement obligations
	The Company’s asset retirement obligations represent the estimated present value of the estimated cash flows the Company will incur to plug, abandon and remediate its producing properties at the end of their productive lives, in accordance with applicable state laws. Market risk premiums associated with asset retirement obligations are estimated to represent a component of the Company's credit-adjusted risk-free rate that is utilized in the calculations of asset retirement obligations.
	The Company’s asset retirement obligation transactions during the years ended December 31, 2014, 2013 and 2012 are summarized in the table below:
			Years Ended December 31,
	(in thousands)			2014		2013		2012
	Asset retirement obligations, beginning of period		$	101,593	$	86,261	$	59,685
		Liabilities incurred from new wells		5,324		6,338		7,729
		Liabilities assumed in acquisitions		4,065		593		29,113
		Accretion expense for continuing operations		7,072		6,047		4,187
		Accretion expense for discontinued operations		-		-		1,004
		Disposition of wells		-		-		-24,614
		Liabilities settled upon plugging and abandoning wells		-2,926		-3,447		-1,261
		Revision of estimates		4,753		5,801		10,418
	Asset retirement obligations, end of period		$	119,881	$	101,593	$	86,261

Incentive_plans

Incentive plans	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Incentive plans	Note 5. Incentive plans
	Defined contribution plan. The Company sponsors a 401(k) defined contribution plan for the benefit of substantially all employees. During the years ended December 31, 2014, 2013 and 2012, the Company matched 100 percent of employee contributions, not to exceed 10 percent of the employee’s annual salary. The Company’s contributions to the plan for the years ended December 31, 2014, 2013 and 2012 were approximately $8.1 million, $6.6 million and $5.3 million, respectively, of which a portion was recoverable from other working interest owners.
	Stock incentive plan. The Company’s 2006 Stock Incentive Plan, as amended and restated (the “Plan”), provides for granting stock options, restricted stock awards and performance awards to directors, officers and employees of the Company. A total of 7.5 million shares of common stock have been authorized for issuance under the Plan. At December 31, 2014, the Company had 823,975 awards available for future grant.
	Restricted stock awards. All restricted shares are legally issued and outstanding. If an employee terminates employment prior to the restriction lapse date, the awarded shares are forfeited and cancelled and are no longer considered issued and outstanding. A summary of the Company’s restricted stock award activity for the years ended December 31, 2014, 2013 and 2012 is presented below:
								Weighted
								Average
					Number of			Grant Date
					Restricted			Fair Value
					Shares			Per Share
	Restricted stock:
		Outstanding at January 1, 2012			912,013
			Shares granted		470,633		$	98.31
			Shares cancelled / forfeited		-58,727
			Lapse of restrictions		-251,392
		Outstanding at December 31, 2012			1,072,527
			Shares granted		498,468		$	88.19
			Shares cancelled / forfeited		-118,472
			Lapse of restrictions		-236,074
		Outstanding at December 31, 2013			1,216,449
			Shares granted		448,730		$	129.12
			Shares cancelled / forfeited		-89,401
			Lapse of restrictions		-484,469
		Outstanding at December 31, 2014			1,091,309
	For restricted stock awards granted, stock-based compensation expense is being recognized in the Company's financial statements on an accelerated basis over the awards' vesting periods based on their fair values on the dates of grant. The restricted stock-based compensation awards generally vest over a period ranging from one to five years. The Company utilizes the average of the grant date’s high and low stock prices for the fair value of restricted stock.
	The following table summarizes information about stock-based compensation for the Company’s restricted stock awards activity under the Plan for years ended December 31, 2014, 2013 and 2012:
					Years Ended December 31,
	(in thousands)					2014			2013			2012
	Grant date fair value for awards during the period (a)				$	57,940		$	44,947		$	46,268
	Stock-based compensation expense from restricted stock				$	36,585		$	30,984		$	29,685
	Income taxes and other information:
		Income tax benefit related to restricted stock			$	13,672		$	11,650		$	11,349
		Deductions in current taxable income related to restricted stock vestings			$	58,908		$	20,883		$	23,570
	(a) The year ended December 31, 2013 includes the effects of $1 million due to modifications of certain stock-based awards.
	Stock option awards.  A summary of the Company’s stock option award activity under the Plan for the years ended December 31, 2014, 2013 and 2012 is presented below:
					Years Ended December 31,
					2014					2013					2012
								Weighted					Weighted				Weighted
								Average					Average				Average
					Number of			Exercise		Number of			Exercise		Number of		Exercise
					Options			Price		Options			Price		Options		Price
	Stock options:
		Outstanding at beginning of period			255,537		$	21.5		429,879		$	20.28		930,178	$	18.1
			Options exercised		-207,824		$	22.42		-174,342		$	18.48		-500,299	$	16.24
		Outstanding at end of period			47,713		$	17.49		255,537		$	21.5		429,879	$	20.28
		Vested and exercisable at end of period			47,713		$	17.49		255,537		$	21.5		403,077	$	20.24
	The intrinsic value of options exercised during 2014, 2013 and 2012 was approximately $23.2 million, $13.2 million and $39.8 million, respectively, based on the difference between the market price at the exercise date and the option exercise price.
	The following table summarizes information about the Company’s vested and exercisable stock options outstanding at December 31, 2014:
								Weighted
								Average			Weighted			Intrinsic
			Range of					Remaining			Average			Value
			Exercise			Number		Contractual			Exercise			of
			Prices			Vested		Life			Price			Options
														(in thousands)
	December 31, 2014:
		Vested and exercisable options:
			$12.00			5,636		0.91 years		$	12		$	495
			$12.50 - $15.50			15,000		2.62 years		$	12.85			1,304
			$20.00 - $23.00			27,077		3.98 years		$	21.2			2,127
						47,713		3.19 years		$	17.49		$	3,926
	The following table summarizes information about stock-based compensation for stock options for the years ended December 31, 2014, 2013 and 2012:
				Years Ended December 31,
	(in thousands)					2014			2013			2012
	Stock-based compensation expense from stock options				$	-		$	14		$	187
	Income taxes and other information:
	Income tax benefit related to stock options			$	-		$	6		$	72
	Deductions in current taxable income related to stock options exercised			$	23,208		$	13,193		$	39,828
Performance unit awards. During the years ended December 31, 2014 and 2013, the Company awarded performance units to its officers under the Plan. The number of shares of common stock that will ultimately be issued will be determined by a combination of (i) comparing the Company's total shareholder return relative to the total shareholder return of a predetermined group of peer companies at the end of the performance period and (ii) the Company’s absolute total shareholder return at the end of the performance period. The performance period is 36 months. The grant date fair value was determined using the Monte Carlo simulation method and is being expensed ratably over the performance period. Expected volatilities utilized in the model were estimated using a historical period consistent with the remaining performance period of approximately three years. The risk-free interest rate was based on the United States Treasury rate for a term commensurate with the expected life of the grant.
The Company used the following assumptions to estimate the fair value of performance unit awards granted during the years ended December 31, 2014 and 2013:
				Years Ended December 31,
				2014			2013
Risk-free interest rate				0.76%			0.37%
Range of volatilities				29.2% - 42.2%			31.5% - 45.1%
The following table summarizes the performance unit activity for the years ended December 31, 2014 and 2013:
					Number of			Grant Date
					Units (a)			Fair Value
Performance units:
	Outstanding at December 31, 2012				-
		Units granted			110,889		$	111.4
	Outstanding at December 31, 2013				110,889
		Units granted			139,425		$	139.54
	Outstanding at December 31, 2014				250,314
(a)	Reflects the amount of performance units granted. The actual payout of shares will be between zero and 300 percent of the performance units granted depending on the Company's performance at the end of the performance period.
The following table summarizes information about stock-based compensation expense for performance units for the years ended December 31, 2014
				Years Ended December 31,
(in thousands)					2014			2013
Grant date fair value for awards during the period				$	19,455		$	12,352
Stock-based compensation expense from performance units				$	10,545		$	4,080
Income tax benefit related to performance units				$	3,941		$	1,560
Future stock-based compensation expense. The following table reflects the future stock-based compensation expense to be recorded for all the stock-based compensation awards that were outstanding at December 31, 2014:
				Restricted			Performance
(in thousands)				Stock			Units			Total
2015			$	30,290		$	10,668		$	40,958
2016				18,819			6,514			25,333
2017				7,066			-			7,066
2018				851			-			851
2019				3			-			3
	Total		$	57,029		$	17,182		$	74,211

Disclosures_about_fair_value_o

Disclosures about fair value of financial instruments	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Disclosures about fair value of financial instruments	Note 6. Disclosures about fair value of financial instruments
	The Company uses a valuation framework based upon inputs that market participants use in pricing an asset or liability, which are classified into two categories: observable inputs and unobservable inputs. Observable inputs represent market data obtained from independent sources, whereas unobservable inputs reflect a company’s own market assumptions, which are used if observable inputs are not reasonably available without undue cost and effort. These two types of inputs are further prioritized into the following fair value input hierarchy:
	Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities. The Company considers active markets to be those in which transactions for the assets or liabilities occur in sufficient frequency and volume to provide pricing information on an ongoing basis.
	Level 2: Quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability. This category includes those derivative instruments that the Company values using observable market data. Substantially all of these inputs are observable in the marketplace throughout the full term of the derivative instrument, can be derived from observable data, or supported by observable levels at which transactions are executed in the marketplace. Level 2 instruments primarily include non-exchange traded derivatives such as over-the-counter commodity price swaps, basis swaps, collars and floors, investments and interest rate swaps. The Company’s valuation models are primarily industry-standard models that consider various inputs including: (i) quoted forward prices for commodities, (ii) time value, (iii) current market and contractual prices for the underlying instruments and (iv) volatility factors, as well as other relevant economic measures.
	Level 3: Measured based on prices or valuation models that require inputs that are both significant to the fair value measurement and less observable from objective sources (i.e., supported by little or no market activity). The Company’s valuation models are primarily industry-standard models that consider various inputs including: (i) quoted forward prices for commodities, (ii) time value, (iii) volatility factors and (iv) current market and contractual prices for the underlying instruments, as well as other relevant economic measures.
	Financial Assets and Liabilities Measured at Fair Value
	The following table presents the carrying amounts and fair values of the Company’s financial instruments at December 31, 2014 and 2013:
					31-Dec-14						31-Dec-13
					Carrying			Fair			Carrying			Fair
	(in thousands)				Value			Value			Value			Value
		Assets:
			Derivative instruments		$	752,700		$	752,700		$	1,556		$	1,556
		Liabilities:
			Derivative instruments		$	-		$	-		$	67,789		$	67,789
			Credit facility		$	139,500		$	131,068		$	250,000		$	250,770
			7.0% senior notes due 2021		$	600,000		$	625,500		$	600,000		$	660,000
			6.5% senior notes due 2022		$	600,000		$	628,500		$	600,000		$	649,500
			5.5% senior notes due 2022		$	600,000		$	598,500		$	600,000		$	619,500
			5.5% senior notes due 2023		$	1,577,820		$	1,573,875		$	1,580,421		$	1,627,834
	Cash and cash equivalents, accounts receivable, other current assets, accounts payable, interest payable and other current liabilities. The carrying amounts approximate fair value due to the short maturity of these instruments.
	Credit facility.  The fair value of the Company’s credit facility is estimated by discounting the principal and interest payments at the Company’s credit-adjusted discount rate at the reporting date, which utilizes inputs that are Level 2 measurements in the fair value hierarchy.
	Senior notes. The fair values of the Company’s senior notes are based on quoted market prices. The debt securities are not actively traded and, therefore, are classified as Level 2 in the fair value hierarchy.
	Derivative instruments. The fair value of the Company’s derivative instruments is estimated by management considering various factors, including closing exchange and over-the-counter quotations and the time value of the underlying commitments. Financial assets and liabilities are classified 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 to the fair value measurement requires judgment and may affect the valuation of the fair value of assets and liabilities and their placement within the fair value hierarchy levels. The following tables summarize (i) the valuation of each of the Company’s financial instruments by required fair value hierarchy levels and (ii) the gross fair value by the appropriate balance sheet classification, even when the derivative instruments are subject to netting arrangements and qualify for net presentation in the Company’s consolidated balance sheets at December 31, 2014 and 2013. The Company nets the fair value of derivative instruments by counterparty in the Company’s consolidated balance sheets.
	31-Dec-14
						Fair Value Measurements Using															Net
						Quoted Prices													Gross		Fair Value
						in Active					Significant								Amounts		Presented
						Markets for					Other			Significant					Offset in the		in the
						Identical					Observable			Unobservable					Consolidated		Consolidated
						Assets					Inputs			Inputs			Total		Balance		Balance
	(in thousands)					(Level 1)					(Level 2)			(Level 3)			Fair Value		Sheet		Sheet
		Assets
			Current:
				Commodity derivatives			$	-		$	501,717		$	-		$	501,717	$	-11,366	$	490,351
			Noncurrent:
				Commodity derivatives				-			262,349			-			262,349		-		262,349
		Liabilities
			Current:
				Commodity derivatives				-			-11,366			-			-11,366		11,366		-
			Noncurrent:
				Commodity derivatives				-			-			-			-		-		-
		Net derivative instruments					$	-		$	752,700		$	-		$	752,700	$	-	$	752,700
	31-Dec-13
						Fair Value Measurements Using															Net
						Quoted Prices													Gross		Fair Value
						in Active					Significant								Amounts		Presented
						Markets for					Other			Significant					Offset in the		in the
						Identical					Observable			Unobservable					Consolidated		Consolidated
						Assets					Inputs			Inputs			Total		Balance		Balance
	(in thousands)					(Level 1)					(Level 2)			(Level 3)			Fair Value		Sheet		Sheet
		Assets
			Current:
				Commodity derivatives			$	-		$	12,819		$	-		$	12,819	$	-12,229	$	590
			Noncurrent:
				Commodity derivatives				-			5,300			-			5,300		-4,334		966
		Liabilities
			Current:
				Commodity derivatives				-			-65,930			-			-65,930		12,229		-53,701
			Noncurrent:
				Commodity derivatives				-			-18,422			-			-18,422		4,334		-14,088
		Net derivative instruments					$	-		$	-66,233		$	-		$	-66,233	$	-	$	-66,233
	Concentrations of credit risk. As of December 31, 2014, the Company’s primary concentration of credit risks are the risk of collecting accounts receivable and the risk of counterparties’ failure to perform under derivative obligations. See Note 11 for information regarding the Company's major customers and derivative counterparties.
	The Company has entered into International Swap Dealers Association Master Agreements (“ISDA Agreements”) with each of its derivative counterparties. The terms of the ISDA Agreements provide the Company and the counterparties with rights of set off upon the occurrence of defined acts of default by either the Company or a counterparty to a derivative, whereby the party not in default may set off all derivative liabilities owed to the defaulting party against all derivative asset receivables from the defaulting party. See Note 7 for additional information regarding the Company's derivative activities.
	Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
Certain assets and liabilities are reported at fair value on a nonrecurring basis in the Company’s consolidated balance sheets. The following methods and assumptions were used to estimate the fair values:
Impairments of long-lived assets – The Company reviews its long-lived assets to be held and used, including proved oil and natural gas properties, whenever events or circumstances indicate that the carrying value of those assets may not be recoverable, for instance when there are declines in commodity prices or well performance. An impairment loss is indicated if the sum of the expected undiscounted future net cash flows is less than the carrying amount of the assets. In this circumstance, the Company recognizes an impairment loss for the amount by which the carrying amount of the asset exceeds the estimated fair value of the asset. The Company reviews its oil and natural gas properties by depletion base or by individual well for those wells not constituting part of a depletion base. For each property determined to be impaired, an impairment loss equal to the difference between the carrying value of the properties and the estimated fair value of the properties would be recognized at that time.
The Company calculates the estimated fair values using a discounted future cash flow model. Management’s assumptions associated with the calculation of discounted future cash flows include commodity prices based on NYMEX futures price strips (Level 1), as well as Level 3 assumptions including (i) pricing adjustments for differentials, (ii) production costs, (iii) capital expenditures, (iv) production volumes and (v) estimated reserves.
As a result of management’s assessments, the Company recognized impairment charges to reduce the carrying values to their fair values. The following table reports the carrying amount, estimated fair value and impairment expense of long-lived assets for the indicated periods:
						Estimated
			Carrying			Fair Value			Impairment
(in thousands)			Amount			(Level 3)			Expense
Dec-14		$	677,021		$	245,346		$	431,675
Sep-14		$	26,790		$	11,314		$	15,476
Jun-13		$	84,140		$	18,765		$	65,375
It is reasonably possible that the estimate of undiscounted future net cash flows may change in the future resulting in the need to further impair carrying values. The primary factors that may affect estimates of future cash flows are (i) commodity futures prices, (ii) increases or decreases in production and capital costs, (iii) future reserve adjustments, both positive and negative, to proved reserves and appropriate risk-adjusted probable and possible reserves and (iv) results of future drilling activities.
Additionally, based on the factors above as of December 31, 2014, the Company determined that undiscounted future cash flows attributable to certain depletion groups indicated that their carrying amounts were expected to be recovered; however, they may be at risk for impairment if management’s estimates of future cash flows further decline.

Derivative_financial_instrumen

Derivative financial instruments	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative financial instruments	Note 7. Derivative financial instruments
	The Company uses derivative financial instruments to manage its exposure to commodity price fluctuations. Commodity derivative instruments are used to (i) reduce the effect of the volatility of price changes on the oil and natural gas the Company produces and sells, (ii) support the Company’s capital budget and expenditure plans and (iii) support the economics associated with acquisitions. The Company does not enter into derivative financial instruments for speculative or trading purposes. The Company may also enter into physical delivery contracts to effectively provide commodity price hedges. Because these contracts are not expected to be net cash settled, they are considered to be normal sales contracts and not derivatives. Therefore, these contracts are not recorded in the Company’s consolidated financial statements.
	The Company does not designate its derivative instruments to qualify for hedge accounting. Accordingly, the Company reflects changes in the fair value of its derivative instruments in its statements of operations as they occur.
	The following table summarizes the gains and losses reported in earnings related to the commodity derivative instruments for the years ended December 31, 2014, 2013 and 2012:
				Years Ended December 31,
	(in thousands)				2014			2013			2012
	Gain (loss) on derivatives not designated as hedges:
		Oil derivatives		$	869,421		$	-133,890		$	127,293
		Natural gas derivatives			21,496			10,238			150
			Total	$	890,917		$	-123,652		$	127,443
	The following table represents the Company's cash receipts from (payments on) derivatives reported in the Company's cash flows from investing for the years ended December 31, 2014, 2013 and 2012:
				Years Ended December 31,
	(in thousands)				2014			2013			2012
	Cash receipts from (payments on) derivatives not designated as hedges:
		Oil derivatives		$	76,335		$	-41,616		$	22,411
		Natural gas derivatives			-4,352			9,275			1,125
			Total	$	71,983		$	-32,341		$	23,536
	Commodity derivative contracts at December 31, 2014. The following table sets forth the Company’s outstanding derivative contracts at December 31, 2014. When aggregating multiple contracts, the weighted average contract price is disclosed. All of the Company’s derivative contracts at December 31, 2014 are expected to settle by June 30, 2017.
					First		Second		Third		Fourth
					Quarter		Quarter		Quarter		Quarter		Total
	Oil Swaps: (a)
		2015:00:00
			Volume (Bbl)		4,240,000		3,919,000		3,654,000		3,449,000		15,262,000
			Price per Bbl	$	88.32	$	87.5	$	87.57	$	87.42	$	87.73
		2016:00:00
			Volume (Bbl)		3,218,000		3,068,000		2,958,000		105,000		9,349,000
			Price per Bbl	$	90.43	$	90.9	$	90.46	$	88.28	$	90.57
		2017:00:00
			Volume (Bbl)		84,000		84,000		-		-		168,000
			Price per Bbl	$	87	$	87	$	-	$	-	$	87
	Oil Basis Swaps: (b)
		2015:00:00
			Volume (Bbl)		3,915,000		3,836,500		3,634,000		3,404,000		14,789,500
			Price per Bbl	$	-3.47	$	-3.45	$	-3.44	$	-3.38	$	-3.44
	Natural Gas Swaps: (c)
		2015:00:00
			Volume (MMBtu)		5,850,000		5,915,000		5,980,000		5,980,000		23,725,000
			Price per MMBtu	$	4.16	$	4.16	$	4.16	$	4.16	$	4.16
	Natural Gas Basis Swaps: (d)
		2015:00:00
			Volume (MMBtu)		1,350,000		1,365,000		1,380,000		1,380,000		5,475,000
			Price per MMBtu	$	-0.13	$	-0.13	$	-0.13	$	-0.13	$	-0.13
	(a) The index prices for the oil price swaps are based on the NYMEX – West Texas Intermediate (“WTI”) monthly average futures price.
	(b) The basis differential price is between Midland – WTI and Cushing – WTI.
	(c) The index prices for the natural gas price swaps are based on the NYMEX – Henry Hub last trading day futures price.
	(d) The basis differential price is between the El Paso Permian delivery point and NYMEX – Henry Hub delivery point.
	Derivative counterparties. The Company uses credit and other financial criteria to evaluate the credit standing of, and to select, counterparties to its derivative instruments. Although the Company does not obtain collateral or otherwise secure the fair value of its derivative instruments, associated credit risk is mitigated by the Company’s credit risk policies and procedures. See additional information in Note 11.

Debt

Debt	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Debt	Note 8. Debt
	The Company’s debt consists of the following at December 31, 2014 and 2013:
						December 31,
	(in thousands)					2014			2013
	Credit facility				$	139,500		$	250,000
	7.0% unsecured senior notes due 2021					600,000			600,000
	6.5% unsecured senior notes due 2022					600,000			600,000
	5.5% unsecured senior notes due 2022					600,000			600,000
	5.5% unsecured senior notes due 2023					1,550,000			1,550,000
	Unamortized original issue premium (discount), net					27,820			30,421
		Less: current portion				-			-
			Total long-term debt		$	3,517,320		$	3,630,421
	Credit facility. The Company’s credit facility, as amended and restated (the “Credit Facility”), has a maturity date of May 9, 2019. The Company’s borrowing base is $3.25 billion until the next scheduled borrowing base redetermination in May 2015, and commitments from the Company’s bank group total $2.5 billion. Between scheduled borrowing base redeterminations, the Company and the lenders (requiring a 66 2/3 percent vote), may each request one special redetermination.
	Advances on the Credit Facility bear interest, at the Company’s option, based on (i) the prime rate of JPMorgan Chase Bank (“JPM Prime Rate”) (3.25 percent at December 31, 2014) or (ii) a Eurodollar rate (substantially equal to the LIBOR). At December 31, 2014, the interest rates of Eurodollar rate advances and JPM Prime Rate advances varied, with interest margins ranging from 125 to 225 basis points and 25 to 125 basis points per annum, respectively, depending on the balance outstanding on the Credit Facility. During the years ended December 31, 2014, 2013 and 2012, the Company incurred commitment fees on the unused portion of the available commitments of $7.7 million, $8.3 million and $6.3 million, respectively. Under the current Credit Facility, commitment fees range from 30 to 37.5 basis points per annum. The Company had approximately $2.4 billion of unused commitments under its credit facility at December 31, 2014. Based on the Company’s current ratio as defined in its credit facility as part of its financial covenants, at December 31, 2014, the Company’s additional borrowings would be limited to approximately $1.6 billion.
	The Company’s obligations under the Credit Facility are secured by a first lien on substantially all of its oil and natural gas properties. At December 31, 2014, all of the Company’s subsidiaries are guarantors and have had their equity pledged to secure borrowings under the Credit Facility.
	The Credit Facility contains various restrictive covenants and compliance requirements which include:
	maintenance of certain financial ratios, including (i) maintenance of a quarterly ratio of total debt to consolidated earnings before interest expense, income taxes, depletion, depreciation, and amortization, exploration expense and other noncash income and expenses to be no greater than 4.25 to 1.0, and (ii) maintenance of a ratio of current assets to current liabilities, excluding noncash assets and liabilities related to financial derivatives and asset retirement obligations and including the unfunded amounts under the Credit Facility, to be not less than 1.0 to 1.0;
	limits on the incurrence of certain indebtedness and certain types of liens;
	restrictions as to mergers, combinations and dispositions of assets; and
	limits on the payment of cash dividends.
	The Company recorded a loss on extinguishment of debt related to the Credit Facility of approximately $4.3 million for the year ended December 31, 2014. This amount includes the proportional amount of unamortized deferred loan costs associated with banks with lesser commitments in the amended credit facility syndicate.
	Senior notes. Interest on the Company’s senior notes is paid in arrears semi-annually. The senior notes are fully and unconditionally guaranteed on a senior unsecured basis by all subsidiaries of the Company, subject to customary release provisions as described in Note 16.
	On June 3, 2013, the Company received tenders and consents from the holders of approximately $225.6 million in aggregate principal amount, or approximately 75.2 percent, of its outstanding 8.625% senior notes due 2017 (the “8.625% Notes”) in connection with a cash tender offer for any and all of the 8.625% Notes at a price of 106.922 percent of the unpaid principal amount.
	On June 21, 2013, the Company redeemed the remaining outstanding 8.625% Notes not purchased in the tender offer at a redemption price of 106.516 percent of the unpaid principal amount plus accrued and unpaid interest through June 20, 2013.
	The Company recorded a loss on extinguishment of debt related to the tender offer and redemption of its 8.625% Notes of approximately $28.6 million for the year ended December 31, 2013. This amount includes approximately $20.4 million associated with the premium paid for the tender offer and redemption of the notes, approximately $5.5 million of unamortized deferred loan costs and approximately $2.7 million of unamortized discount.
	On June 4, 2013, the Company completed the issuance of an additional $850 million in principal amount of its 5.5% senior notes due 2023 (the “Offering”) at 103.75 percent of par (resulting in a 4.884% yield) for net proceeds of approximately $867.8 million. The Company used a portion of the net proceeds from the Offering to fund the tender offer and redemption of the 8.625% Notes and to pay down amounts outstanding on the Credit Facility.
	At December 31, 2014, the Company was in compliance with the covenants under its debt instruments.
	Future benefit to interest expense from original issue premium at December 31, 2014 was as follows:
	(in thousands)
	2015			$		2,747
	2016					2,900
	2017					3,062
	2018					3,233
	2019					3,413
	Thereafter					12,465
		Total		$		27,820
	Principal maturities of long-term debt. Principal maturities of long-term debt outstanding at December 31, 2014 are as follows:
	(in thousands)
	2015			$		-
	2016					-
	2017					-
	2018					-
	2019					139,500
	Thereafter					3,350,000
		Total		$		3,489,500
	Interest expense. The following amounts have been incurred and charged to interest expense for the years ended December 31, 2014, 2013 and 2012:
							Years Ended December 31,
	(in thousands)							2014			2013		2012
	Cash payments for interest						$	211,342		$	200,961	$	158,715
	Amortization of original issue discount (premium)							-2,599			-1,248		462
	Amortization of deferred loan origination costs							10,937			13,172		11,958
	Net changes in accruals							-737			5,696		11,570
		Interest costs incurred						218,943			218,581		182,705
	Less: capitalized interest							-2,282			-		-
		Total interest expense					$	216,661		$	218,581	$	182,705

Commitments_and_contingencies

Commitments and contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Note 9. Commitments and contingencies
	Severance agreements. The Company has entered into severance and change in control agreements with all of its officers. The current annual salaries for the Company’s officers covered under such agreements total approximately $7.4 million.
	Indemnifications. The Company has agreed to indemnify its directors and officers with respect to claims and damages arising from certain acts or omissions taken in such capacity.
	Legal actions. The Company is a party to proceedings and claims incidental to its business. While many of these matters involve inherent uncertainty, the Company believes that the amount of the liability, if any, ultimately incurred with respect to any such proceedings or claims will not have a material adverse effect on the Company’s consolidated financial position as a whole or on its liquidity, capital resources or future results of operations. The Company will continue to evaluate proceedings and claims involving the Company on a regular basis and will establish and adjust any reserves as appropriate to reflect its assessment of the then current status of the matters.
	Severance tax, royalty and joint interest audits. The Company is subject to routine severance, royalty and joint interest audits from regulatory bodies and non-operators and makes accruals as necessary for estimated exposure when deemed probable and estimable. Additionally, the Company is subject to various possible contingencies that arise primarily from interpretations affecting the oil and natural gas industry. Such contingencies include differing interpretations as to the prices at which oil and natural gas sales may be made, the prices at which royalty owners may be paid for production from their leases, allowable costs under joint interest arrangements and other matters. At December 31, 2014 and 2013, the Company had $12.3 million and $12.2 million accrued for estimated exposure, respectively. Although we believe that we have estimated our exposure with respect to the various laws and regulations, administrative rulings and interpretations thereof, adjustments could be required as new interpretations and regulations are issued.
	Commitments. The Company periodically enters into contractual arrangements under which the Company is committed to expend funds. The following table summarizes the Company’s commitments at December 31, 2014:
		Payments Due By Period
	(in thousands)		Total			2015		2016		2017		2018		2019		Thereafter
	Purchase obligations (a)	$	167,174		$	57,489	$	30,017	$	15,080	$	21,077	$	7,606	$	35,905
	(a) Relates to purchase agreements we have entered into including daywork drilling contracts, water commitment agreements, throughput volume delivery commitments and power commitments.
	____________________________________________________________________________________
	Operating leases. The Company leases vehicles, equipment and office facilities under non-cancellable operating leases. Lease payments associated with these operating leases for the years ended December 31, 2014, 2013 and 2012 were approximately $7.2 million, $5.7 million and $4.7 million, respectively.
	Future minimum lease commitments under non-cancellable operating leases at December 31, 2014 are as follows:
	(in thousands)
	2015			$	7,245
	2016				5,589
	2017				5,577
	2018				4,787
	2019				4,112
	Thereafter				8,905
		Total		$	36,215

Income_taxes

Income taxes	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income taxes	Note 10. Income taxes
	The Company uses an asset and liability approach for financial accounting and reporting for income taxes. The Company’s objectives of accounting for income taxes are to recognize (i) the amount of taxes payable or refundable for the current year and (ii) deferred tax liabilities and assets for the future tax consequences of events that have been recognized in its financial statements or tax returns. The Company and its subsidiaries file a federal corporate income tax return on a consolidated basis. The tax returns and the amount of taxable income or loss are subject to examination by federal and state taxing authorities. At December 31, 2014 the Company had current income taxes receivable of approximately $32.9 million and current income taxes payable of approximately $1.1 million. At December 31, 2013 the Company had current income taxes receivable of approximately $10.7 million and current income taxes payable of approximately $1.7 million.
	The Company continually assesses both positive and negative evidence to determine whether it is more likely than not that deferred tax assets can be realized prior to their expiration. Management monitors company-specific, oil and natural gas industry and worldwide economic factors and assesses the likelihood that the Company’s net operating loss carryforwards (“NOLs”), if any, and other deferred tax attributes in the United States, state, and local tax jurisdictions will be utilized prior to their expiration. At December 31, 2014 and 2013, the Company had no valuation allowances related to its deferred tax assets.
	At December 31, 2014, the Company did not have any significant uncertain tax positions requiring recognition in the financial statements. The tax years 2011 through 2014 remain subject to examination by the major tax jurisdictions.
	Income tax provision. The Company’s income tax provision and amounts separately allocated were attributable to the following items for the years ended December 31, 2014, 2013 and 2012:
							Years Ended December 31,
	(in thousands)							2014			2013		2012
	Income from continuing operations						$	317,785		$	118,237	$	251,041
	Income from discontinued operations							-			7,518		14,519
	Changes in stockholders' equity:
		Excess tax benefits related to stock-based compensation						-16,480			-6,147		-18,963
							$	301,305		$	119,608	$	246,597
	The Company’s income tax provision attributable to income from continuing operations consisted of the following for the years ended December 31, 2014, 2013 and 2012:
							Years Ended December 31,
	(in thousands)							2014			2013		2012
	Current:
		U.S. federal					$	16,621		$	12,504	$	7,066
		U.S. state and local						4,997			3,306		2,156
			Total current income tax provision					21,618			15,810		9,222
	Deferred:
		U.S. federal						278,615			119,985		210,527
		U.S. state and local						17,552			-17,558		31,292
			Total deferred income tax provision					296,167			102,427		241,819
				Total income tax provision attributable to income from
					continuing operations		$	317,785		$	118,237	$	251,041
	The reconciliation between the income tax expense computed by multiplying pretax income from continuing operations by the United States federal statutory rate and the reported amounts of income tax expense from continuing operations is as follows:
							Years Ended December 31,
	(in thousands)							2014			2013		2012
	Income at U.S. federal statutory rate						$	299,586		$	125,006	$	230,745
	State income taxes (net of federal tax effect)							22,826			12,505		21,192
	Revisions of previous estimates							738			1,400		219
	Change in estimated effective statutory state income tax							-7,945			-21,876		-
	Nondeductible expense & other							2,580			1,202		-1,115
		Income tax expense					$	317,785		$	118,237	$	251,041
	Effective tax rate							37.10%			33.10%		38.10%
	The Company monitors changes in enacted tax rates for the jurisdictions in which it operates. During 2013, the state of New Mexico passed legislation to phase in a tax rate reduction over the next five years. In addition, the Company monitors its state tax apportionment footprint and makes updates for changes in its projected activity, including changes in budgets and drilling plans.  Based upon the Company’s projected future activity for the states in which it conducts business, the timing for when it anticipates its deferred tax items to become taxable and enacted tax rates at such time deferred items become taxable, the Company has revised its estimated state rate and recorded an additional deferred tax benefit of $7.9 million and $21.9 million during 2014 and 2013, respectively.
	The Company’s income tax provision attributable to income from discontinued operations consisted of the following for the years ended December 31, 2013 and 2012:
							Years Ended December 31,
	(in thousands)							2013			2012
	Current:
		U.S. federal					$	144		$	14,023
		U.S. state and local						25			1,667
			Total current income tax expense					169			15,690
	Deferred:
		U.S. federal						6,397			-1,392
		U.S. state and local						952			221
			Total deferred income tax provision					7,349			-1,171
				Total income tax provision attributable to income from discontinued operations			$	7,518		$	14,519
	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities were as follows:
						December 31,
	(in thousands)					2014				2013
	Deferred tax assets:
		Stock-based compensation				$	24,810		$	23,262
		Derivative instruments					-			24,904
		Asset retirement obligation					44,802			38,241
		Other					24,368			9,500
				Total deferred tax assets			93,980			95,907
	Deferred tax liabilities:
		Oil and natural gas properties, principally due to differences in basis and
			depreciation and the deduction of intangible drilling costs for tax purposes				-1,396,756			-1,383,929
		Intangible assets - operating rights					-10,148			-10,759
		Derivative instruments					-281,303			-
		Other					-6,524			-5,803
				Total deferred tax liability			-1,694,731			-1,400,491
			Net deferred tax liability		$	-1,600,751		$	-1,304,584

Major_customers_and_derivative

Major customers and derivative counterparties	12 Months Ended
	Dec. 31, 2014
Major Customer Disclosure [Abstract]
Major Customers and Derivative Counterparties [Text Block]	Note 11. Major customers and derivative counterparties
	Sales to major customers. The Company’s share of oil and natural gas production is sold to various purchasers. The Company is of the opinion that the loss of any one purchaser would not have a material adverse effect on the ability of the Company to sell its oil and natural gas production.
	The following purchasers individually accounted for 10 percent or more of the consolidated oil and natural gas revenues, including the revenues from discontinued operations, during the years ended December 31, 2014, 2013 and 2012:
			Years Ended December 31,
			2014	2013	2012
	Holly Frontier Refining and Marketing, LLC		17%	30%	26%
	Enterprise Crude Oil LLC		12%	13%	6%
	Western Refining Company LP		12%	1%	-
	Phillips 66		8%	6%	14%
	At December 31, 2014, the Company had receivables from Holly Frontier Refining and Marketing, LLC, Enterprise Crude Oil LLC and Western Refining Company LP of $48.6 million, $23.0 million and $19.3 million, respectively, which are reflected in accounts receivable — oil and natural gas in the accompanying consolidated balance sheets.
	Derivative counterparties. The Company uses credit and other financial criteria to evaluate the credit standing of, and to select, counterparties to its derivative instruments. The Company’s Credit Facility requires that the senior unsecured debt ratings of the Company’s derivative counterparties be (i) not less than either A- by Standard & Poor’s Rating Group rating system or A3 by Moody’s Investors Service, Inc. rating system or (ii) a lender or related affiliate under the Company’s Credit Facility. At December 31, 2014 and 2013, the counterparties with whom the Company had outstanding derivative contracts met or exceeded these criteria. Although the Company does not obtain collateral or otherwise secure the fair value of its derivative instruments, management believes the associated credit risk is mitigated by the Company’s credit risk policies and procedures and by the criteria of the Company’s Credit Facility.
	At December 31, 2014, the Company had a net asset position of $752.7 million as a result of outstanding derivative contracts from the following counterparties:
	(in thousands)
	J.P. Morgan Chase Bank	$	134,735
	Wells Fargo Bank, N.A.		84,523
	Barclays Bank PLC		81,979
	Bank of Montreal		59,789
	KeyBank National Association		59,702
	Citibank, N.A.		55,826
	Canadian Imperial Bank of Commerce		48,466
	Merrill Lynch Commodities, Inc.		46,738
	Union Bank, N.A.		33,986
	Natixis		32,874
	ING Capital Markets LLC		30,496
	Other		83,586
	Total	$	752,700

Related_party_transactions

Related party transactions	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Related party transactions	Note 12. Related party transactions
	The following table summarizes payments made to related parties and reported in the Company’s consolidated statements of operations for the periods presented:
		Years Ended December 31,
	(in thousands)		2014		2013		2012
	Amounts paid to a partnership in which a director has an ownership interest (a)	$	15,181	$	7,255	$	2,444
	Royalties paid to a director and certain officers of the Company (b)	$	383	$	43	$	77
	Amounts paid under consulting agreement with Steven L. Beal (c)	$	-	$	865	$	251
	Amounts include royalties on certain properties and lease bonus payments paid to a partnership in which a director of the Company is the general partner and owns a 3.5 percent partnership interest.
	Payments made to a director and certain officers (or affiliated entities) who own revenue, overriding royalty interests or net profits interests in properties owned by the Company.
	On June 30, 2009, Steven L. Beal, the Company’s then-president and chief operating officer, retired from such positions. On June 9, 2009, the Company entered into a consulting agreement (the “Consulting Agreement”) with Mr. Beal, under which Mr. Beal began serving as a consultant to the Company on July 1, 2009. During the term of the consulting relationship, Mr. Beal received a consulting fee of $20,000 per month and a monthly reimbursement for his medical and dental coverage costs. In August 2013, the Company and Mr. Beal mutually terminated the Consulting Agreement in exchange for the payment to Mr. Beal of $720,000, which termination and payment were approved by the disinterested members of the Company’s Board of Directors.
	At December 31, 2014, the Company had a $76,000 receivable from an officer (or affiliated entities) related to certain properties it operates.
	In June 2013, in connection with the tender offer for the 8.625% Notes, certain directors and officers received an aggregate amount of approximately $1.3 million for the 8.625% Notes they owned. The tender offer was approved by the disinterested members of the Company’s Board of Directors.

Discontinued_operations

Discontinued operations	12 Months Ended
	Dec. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]
Discontinued operations	Note 13. Discontinued operations
	In December 2012, the Company closed the sale of certain of its non-core assets for cash consideration of approximately $503.1 million, which resulted in a pre-tax gain of approximately $0.9 million. As a result of post-closing adjustments during the year ended December 31, 2013, the Company made a positive adjustment to gain (loss) on disposition of assets of approximately $19.6 million. The Company reflected the results of operations of this divestiture as discontinued operations, rather than as a component of continuing operations.
	The following table represents the components of the Company’s discontinued operations for the years ended December 31, 2013 and 2012:
				Years Ended December 31,
	(in thousands)			2013		2012
	Operating revenues:
		Oil sales		$	-	$	101,359
		Natural gas sales			-		18,578
			Total operating revenues		-		119,937
	Operating costs and expenses:
		Oil and natural gas production			-		34,270
		Exploration and abandonments			-		334
		Depreciation, depletion and amortization (a)			-		30,140
		Accretion of discount on asset retirement obligations (a)			-		1,004
		General and administrative (b)			-		-2,493
			Total operating costs and expenses		-		63,255
	Income from operations				-		56,682
	Other income (expense):
		Gain (loss) on disposition of assets, net (a)			19,599		-18,704
	Income from discontinued operations before income taxes				19,599		37,978
	Income tax benefit (expense):
		Current			-169		-15,690
		Deferred (a)			-7,349		1,171
	Income from discontinued operations, net of tax			$	12,081	$	23,459
	(a)		Represents the significant non-cash components of discontinued operations.
	(b)		Represents the fees received from third-parties for operating oil and natural gas properties that were sold. The Company reflects these fees as a reduction of general and administrative expenses.

Net_income_per_share

Net income per share	12 Months Ended
	Dec. 31, 2014
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Net income per share	Note 14. Net income per share
	The Company uses the two-class method of calculating net income per share because certain of the Company’s unvested share-based awards qualify as participating securities. Participating securities participate in income proportionate to the weighted average number of outstanding common shares, but are not assumed to participate in the Company’s net losses because they are not contractually obligated to do so. Accordingly, allocations of earnings to participating securities are included in the Company’s calculations of basic and diluted earnings per share from continuing operations, discontinued operations and net income attributable to common stockholders.
	The following tables reconcile the Company’s income from continuing operations, income from discontinued operations and net income attributable to common stockholders to the basic and diluted earnings used to determine the Company’s income per share amounts for the years ended December 31, 2014, 2013 and 2012, respectively, under the two-class method:
						Year Ended
						31-Dec-14
					Continuing			Discontinued
	(in thousands, except per share amounts)				Operations			Operations		Total
	Income as reported				$	538,175		$	-	$	538,175
	Participating basic earnings					-5,961			-		-5,961
		Basic income attributable to common stockholders				532,214			-		532,214
	Reallocation of participating earnings					16			-		16
		Diluted income attributable to common stockholders			$	532,230		$	-	$	532,230
	Income per common share:
		Basic			$	4.89		$	-	$	4.89
		Diluted			$	4.88		$	-	$	4.88
						Year Ended
						31-Dec-13
					Continuing			Discontinued
	(in thousands, except per share amounts)				Operations			Operations		Total
	Income as reported				$	238,922		$	12,081	$	251,003
	Participating basic earnings					-2,610			-132		-2,742
		Basic income attributable to common stockholders				236,312			11,949		248,261
	Reallocation of participating earnings					4			-		4
		Diluted income attributable to common stockholders			$	236,316		$	11,949	$	248,265
	Income per common share:
		Basic			$	2.28		$	0.11	$	2.39
		Diluted			$	2.28		$	0.11	$	2.39
						Year Ended
						31-Dec-12
					Continuing			Discontinued
	(in thousands, except per share amounts)				Operations			Operations		Total
	Income as reported				$	408,230		$	23,459	$	431,689
	Participating basic earnings					-			-		-
		Basic income attributable to common stockholders				408,230			23,459		431,689
	Reallocation of participating earnings					-			-		-
		Diluted income attributable to common stockholders			$	408,230		$	23,459	$	431,689
	Income per common share:
		Basic			$	3.96		$	0.22	$	4.18
		Diluted			$	3.93		$	0.22	$	4.15
	The following table is a reconciliation of the basic weighted average common shares outstanding to diluted weighted average common shares outstanding for the years ended December 31, 2014, 2013 and 2012:
					Years Ended December 31,
	(in thousands)				2014		2013		2012
	Weighted average common shares outstanding:
		Basic			108,844		103,744		103,190
			Dilutive common stock options		83		165		354
			Dilutive restricted stock		-		-		428
			Dilutive performance units		205		4		-
		Diluted			109,132		103,913		103,972
	The following table is a summary of the restricted stock and performance units, which were not included in the computation of diluted net income per share, as inclusion of these items would be antidilutive:
				Years Ended December 31,
	(in thousands)			2014		2013		2012
	Number of antidilutive common shares:
		Antidilutive restricted stock		153		9		95
		Antidilutive performance units		-		83		-

Other_current_liabilities

Other current liabilities	12 Months Ended
	Dec. 31, 2014
Other Liabilities Disclosure [Abstract]
Other current liabilities	Note 15. Other current liabilities
	The following table provides the components of the Company’s other current liabilities at December 31, 2014 and 2013:
					December 31,
	(in thousands)				2014		2013
	Other current liabilities:
		Accrued production costs		$	70,786	$	48,196
		Payroll related matters			34,349		28,498
		Accrued interest			69,264		70,000
		Asset retirement obligations			9,146		4,481
		Other			11,763		5,425
			Other current liabilities	$	195,308	$	156,600

Subsidiary_guarantors

Subsidiary guarantors	12 Months Ended
	Dec. 31, 2014
Guarantees [Abstract]
Subsidiary guarantors	Note 16. Subsidiary guarantors
	All of the Company’s 100 percent owned and controlled subsidiaries have fully and unconditionally guaranteed the Company’s senior notes. The indentures governing the Company’s senior notes provide that the guarantees of its subsidiary guarantors will be released in certain customary circumstances including (i) in connection with any sale, exchange or other disposition, whether by merger, consolidation or otherwise, of the capital stock of that guarantor to a person that is not the Company or a restricted subsidiary of the Company, such that, after giving effect to such transaction, such guarantor would no longer constitute a subsidiary of the Company, (ii) in connection with any sale, exchange or other disposition (other than a lease) of all or substantially all of the assets of that guarantor to a person that is not the Company or a restricted subsidiary of the Company, (iii) upon the merger of a guarantor into the Company or any other guarantor or the liquidation or dissolution of a guarantor, (iv) if the Company designates any restricted subsidiary that is a guarantor to be an unrestricted subsidiary in accordance with the indenture, (v) upon legal defeasance or satisfaction and discharge of the indenture and (vi) upon written notice of such release or discharge by the Company to the trustee following the release or discharge of all guarantees by such guarantor of any indebtedness that resulted in the creation of such guarantee, except a discharge or release by or as a result of payment under such guarantee.
	See Note 8 for a summary of the Company’s senior notes. In accordance with practices accepted by the United States Securities and Exchange Commission (“SEC”), the Company has prepared condensed consolidating financial statements in order to quantify the assets, results of operations and cash flows of such subsidiaries as subsidiary guarantors. One of the entities included in the Company’s consolidated financial statements was formed to effectuate a tax-free exchange of assets. The third-party conveyed ownership to the Company upon completion of the tax-free exchange process. This entity did not guarantee the Company’s senior notes until the conveyance was completed and is referred to as a “Non-Guarantor Subsidiary” in the tables below.
	The following condensed consolidating balance sheets at December 31, 2014 and 2013, condensed consolidating statements of operations and consolidating condensed statements of cash flows for the years ended December 31, 2014, 2013 and 2012, present financial information for Concho Resources Inc. as the Parent on a stand-alone basis (carrying any investments in subsidiaries under the equity method), financial information for the subsidiary guarantors on a stand-alone basis (carrying any investment in non-guarantor subsidiaries under the equity method), financial information for the subsidiary non-guarantor on a stand-alone basis and the consolidation and elimination entries necessary to arrive at the information for the Company on a consolidated basis. All current and deferred income taxes are recorded on Concho Resources Inc., as the subsidiaries are flow-through entities for income tax purposes. The subsidiary guarantors and subsidiary non-guarantor are not restricted from making distributions to the Company.
	Condensed Consolidating Balance Sheet
	31-Dec-14
					Parent			Subsidiary			Consolidating
	(in thousands)				Issuer			Guarantors			Entries			Total
	ASSETS
	Accounts receivable - related parties			$	6,670,744		$	1,201,950		$	-7,872,694		$	-
	Other current assets				569,545			618,851			-			1,188,396
	Oil and natural gas properties, net				-			10,076,878			-			10,076,878
	Property and equipment, net				-			129,136			-			129,136
	Investment in subsidiaries				4,085,045			-			-4,085,045			-
	Other long-term assets				330,792			74,761			-			405,553
		Total assets		$	11,656,126		$	12,101,576		$	-11,957,739		$	11,799,963
	LIABILITIES AND EQUITY
	Accounts payable - related parties			$	1,201,950		$	6,670,744		$	-7,872,694		$	-
	Other current liabilities				217,884			1,209,309			-			1,427,193
	Long-term debt				3,517,320			-			-			3,517,320
	Other long-term liabilities				1,438,184			136,478			-			1,574,662
	Equity				5,280,788			4,085,045			-4,085,045			5,280,788
		Total liabilities and equity		$	11,656,126		$	12,101,576		$	-11,957,739		$	11,799,963
	Condensed Consolidating Balance Sheet
	31-Dec-13
					Parent			Subsidiary			Consolidating
	(in thousands)				Issuer			Guarantors			Entries			Total
	ASSETS
	Accounts receivable - related parties			$	6,115,554		$	1,261,844		$	-7,377,398		$	-
	Other current assets				39,108			481,767			-			520,875
	Oil and natural gas properties, net				-			8,831,265			-			8,831,265
	Property and equipment, net				-			114,783			-			114,783
	Investment in subsidiaries				3,896,741			-			-3,896,741			-
	Other long-term assets				74,013			50,228			-			124,241
		Total assets		$	10,125,416		$	10,739,887		$	-11,274,139		$	9,591,164
	LIABILITIES AND EQUITY
	Accounts payable - related parties			$	1,261,844		$	6,115,554		$	-7,377,398		$	-
	Other current liabilities				126,461			630,407			-			756,868
	Long-term debt				3,630,421			-			-			3,630,421
	Other long-term liabilities				1,348,741			97,185			-			1,445,926
	Equity				3,757,949			3,896,741			-3,896,741			3,757,949
		Total liabilities and equity		$	10,125,416		$	10,739,887		$	-11,274,139		$	9,591,164
	Condensed Consolidating Statement of Operations
	For the Year Ended December 31, 2014
					Parent			Subsidiary			Consolidating
	(in thousands)				Issuer			Guarantors			Entries			Total
	Total operating revenues			$	-		$	2,660,147		$	-		$	2,660,147
	Total operating costs and expenses				888,632			-2,459,034			-			-1,570,402
		Income from operations			888,632			201,113			-			1,089,745
	Interest expense				-216,661			-			-			-216,661
	Loss on extinguishment of debt				-4,316			-			-			-4,316
	Other, net				188,305			-12,809			-188,304			-12,808
		Income before income taxes			855,960			188,304			-188,304			855,960
	Income tax expense				-317,785			-			-			-317,785
		Net income		$	538,175		$	188,304		$	-188,304		$	538,175
	Condensed Consolidating Statement of Operations
	For the Year Ended December 31, 2013
				Parent			Subsidiary			Consolidating
	(in thousands)			Issuer			Guarantors			Entries			Total
	Total operating revenues			$	-		$	2,319,919		$	-		$	2,319,919
	Total operating costs and expenses				-125,924			-1,576,558			-			-1,702,482
		Income (loss) from operations			-125,924			743,361			-			617,437
	Interest expense				-218,581			-			-			-218,581
	Loss on extinguishment of debt				-28,616			-			-			-28,616
Other, net				749,878			-13,136			-749,823			-13,081
	Income before income taxes			376,757			730,225			-749,823			357,159
Income tax expense				-118,237			-			-			-118,237
	Income from continuing operations			258,520			730,225			-749,823			238,922
Income (loss) from discontinued operations, net of tax				-7,517			19,598			-			12,081
	Net income		$	251,003		$	749,823		$	-749,823		$	251,003
Condensed Consolidating Statement of Operations
For the Year Ended December 31, 2012
					Parent			Subsidiary			Subsidiary			Consolidating
(in thousands)					Issuer			Guarantors			Non-Guarantor			Entries			Total
Total operating revenues				$	-		$	1,812,472		$	7,342		$	-		$	1,819,814
Total operating costs and expenses					126,482			-1,090,013			-5,720			-			-969,251
	Income from operations				126,482			722,459			1,622			-			850,563
Interest expense					-182,705			-			-			-			-182,705
Other, net					753,472			-3,148			-6,043			-752,868			-8,587
	Income (loss) before income taxes				697,249			719,311			-4,421			-752,868			659,271
Income tax expense					-251,041			-			-			-			-251,041
	Income (loss) from continuing operations				446,208			719,311			-4,421			-752,868			408,230
Income (loss) from discontinued operations,
	net of tax				-14,519			37,978			-			-			23,459
	Net income (loss)			$	431,689		$	757,289		$	-4,421		$	-752,868		$	431,689
Condensed Consolidating Statement of Cash Flows
For the Year Ended December 31, 2014
				Parent Issuer			Subsidiary Guarantors			Consolidating Entries
(in thousands)													Total
Net cash flows provided by (used in) operating activities			$	-888,369		$	2,562,156		$	-		$	1,673,787
Net cash flows provided by (used in) investing activities				71,983			-2,617,979			-			-2,545,996
Net cash flows provided by financing activities				816,386			55,823			-			872,209
	Net decrease in cash and cash equivalents			-			-			-			-
	Cash and cash equivalents at beginning of period			-			21			-			21
	Cash and cash equivalents at end of period		$	-		$	21		$	-		$	21
Condensed Consolidating Statement of Cash Flows
For the Year Ended December 31, 2013
				Parent			Subsidiary			Consolidating
(in thousands)				Issuer			Guarantors			Entries			Total
Net cash flows provided by (used in) operating activities			$	-487,131		$	1,849,151		$	-		$	1,362,020
Net cash flows used in investing activities				-32,341			-1,864,453			-			-1,896,794
Net cash flows provided by financing activities				519,472			12,443			-			531,915
	Net decrease in cash and cash equivalents			-			-2,859			-			-2,859
	Cash and cash equivalents at beginning of period			-			2,880			-			2,880
	Cash and cash equivalents at end of period		$	-		$	21		$	-		$	21
Condensed Consolidating Statement of Cash Flows
For the Year Ended December 31, 2012
						Parent			Subsidiary			Subsidiary			Consolidating
(in thousands)						Issuer			Guarantors			Non-Guarantor			Entries			Total
Net cash flows provided by (used in)
	operating activities				$	-1,044,006		$	2,278,647		$	2,837		$	-		$	1,237,478
Net cash flows provided by (used in)
	investing activities					23,536			-1,720,242			-543,738			-			-2,240,444
Net cash flows provided by (used in)
	financing activities					1,020,470			-555,867			540,901			-			1,005,504
		Net increase in cash and cash
			equivalents			-			2,538			-			-			2,538
		Cash and cash equivalents at
			beginning of period			-			342			-			-			342
		Cash and cash equivalents at
			end of period		$	-		$	2,880		$	-		$	-		$	2,880

Subsequent_events

Subsequent events	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent events	Note 17. Subsequent events
	New commodity derivative contracts. After December 31, 2014, the Company entered into the following additional oil price swaps and oil basis swaps to hedge additional amounts of the Company’s estimated future production:
					First		Second		Third		Fourth
					Quarter		Quarter		Quarter		Quarter		Total
	Oil Swaps: (a)
		2015:00:00
			Volume (Bbl)		-		660,000		660,000		660,000		1,980,000
			Price per Bbl	$	-	$	56.6	$	56.6	$	56.6	$	56.6
		2016:00:00
			Volume (Bbl)		180,000		180,000		180,000		2,610,000		3,150,000
			Price per Bbl	$	61.04	$	61.04	$	61.04	$	62.48	$	62.23
	Oil Basis Swaps: (b)
		2016:00:00
			Volume (Bbl)		364,000		364,000		368,000		368,000		1,464,000
			Price per Bbl	$	-2.48	$	-2.48	$	-2.48	$	-2.48	$	-2.48
	(a)		The index prices for the oil price swaps are based on the NYMEX – WTI monthly average futures price.
	(b)		The basis differential price is between Midland – WTI and Cushing – WTI.

Summary_of_significant_account1

Summary of significant accounting policies (Policies)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Principles of consolidation	Principles of consolidation. The consolidated financial statements of the Company include the accounts of the Company and its 100 percent owned subsidiaries. In addition, from time to time, a third-party has formed entities to effectuate a tax-free exchange of assets for the Company. The Company has 100 percent control over the decisions of the entities, but has no direct ownership. The third-party conveys ownership to the Company upon completion of the tax-free exchange process. The Company consolidates the financial statements of these entities. All material intercompany balances and transactions have been eliminated.
Discontinued operations	Discontinued operations. The Company made the following divestiture of assets during the period covered by these consolidated financial statements:
	(dollars in millions)
	Date divested					Dec-12
	Net proceeds				$	503.1
	Gain on disposition of assets				$	0.9
	As a result, the Company has reflected the results of operations of these divested assets as discontinued operations, rather than as a component of continuing operations. See Note 13 for additional information regarding this divestiture and its discontinued operations.
Use of estimates in the preparation of financial statements	Use of estimates in the preparation of financial statements. Preparation of financial statements in conformity with generally accepted accounting principles in the United States of America (“U.S. GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting periods. Actual results could differ from these estimates. Depletion of oil and natural gas properties is determined using estimates of proved oil and natural gas reserves. There are numerous uncertainties inherent in the estimation of quantities of proved reserves and in the projection of future rates of production and the timing of development expenditures. Similarly, evaluations for impairment of proved and unproved oil and natural gas properties are subject to numerous uncertainties including, among others, estimates of future recoverable reserves and commodity price outlooks. Other significant estimates include, but are not limited to, the asset retirement obligations, fair value of derivative financial instruments, the fair value of business combinations, fair value of stock-based compensation and income taxes.
Cash equivalents	Cash equivalents. The Company considers all cash on hand, depository accounts held by banks, money market accounts and investments with an original maturity of three months or less to be cash equivalents. The Company’s cash and cash equivalents are held in financial institutions in amounts that exceed the insurance limits of the Federal Deposit Insurance Corporation. However, management believes that the Company’s counterparty risks are minimal based on the reputation and history of the institutions selected.
Accounts receivable	Accounts receivable. The Company sells oil and natural gas to various customers and participates with other parties in the drilling, completion and operation of oil and natural gas wells. Joint interest and oil and natural gas sales receivables related to these operations are generally unsecured. The Company determines joint interest operations accounts receivable allowances based on management’s assessment of the creditworthiness of the joint interest owners and the Company’s ability to realize the receivables through netting of anticipated future production revenues. Receivables are considered past due if full payment is not received by the contractual due date. Past due accounts are generally written off against the allowance for doubtful accounts only after all collection attempts have been exhausted. The Company had an allowance for doubtful accounts of approximately $0.7 million at both December 31, 2014 and 2013.
Inventory	Inventory. Inventory consists primarily of tubular goods and other oilfield equipment that the Company plans to utilize in its ongoing exploration and development activities and is carried at the lower of cost or market value, on a weighted average cost basis.
Deferred loan costs.	Deferred loan costs. Deferred loan costs are stated at cost, net of amortization, which is computed using the effective interest and straight-line methods. The Company had deferred loan costs of $68.4 million and $73.0 million, net of accumulated amortization of $59.7 million and $48.7 million, at December 31, 2014 and December 31, 2013, respectively.
Oil and natural gas properties	Oil and natural gas properties. The Company utilizes the successful efforts method of accounting for its oil and natural gas properties. Under this method all costs associated with productive wells and nonproductive development wells are capitalized, while nonproductive exploration costs are expensed. Capitalized acquisition costs relating to proved properties are depleted using the unit-of-production method based on proved reserves. The depletion of capitalized drilling and development costs is based on the unit-of-production method using proved developed reserves. During the years ended December 31, 2014, 2013 and 2012, the Company recognized depletion expense from continuing and discontinued operations of $960.9 million, $756.0 million and $591.3 million, respectively.
	The Company generally does not carry the costs of drilling an exploratory well as an asset in its consolidated balance sheets following the completion of drilling unless the exploratory well finds oil and natural gas reserves in an area requiring a major capital expenditure and both of the following conditions are met:
	the well has found a sufficient quantity of reserves to justify its completion as a producing well; and
	the Company is making sufficient progress assessing the reserves and the economic and operating viability of the project.
	Due to the capital intensive nature and the geographical location of certain projects, it may take the Company longer than one year to evaluate the future potential of the exploration well and economics associated with making a determination on its commercial viability. In these instances, the project's feasibility is not contingent upon price improvements or advances in technology, but rather the Company's ongoing efforts and expenditures related to accurately predicting the hydrocarbon recoverability based on well information, gaining access to other companies' production, transportation or processing facilities and/or getting partner approval to drill additional appraisal wells. These activities are ongoing and being pursued constantly. Consequently, the Company's assessment of suspended exploratory well costs is continuous until a decision can be made that the well has found proved reserves or is noncommercial and is charged to exploration and abandonments expense. See Note 3 for additional information regarding the Company's suspended exploratory well costs.
	Proceeds from the sales of individual properties and the capitalized costs of individual properties sold or abandoned are credited and charged, respectively, to accumulated depletion. Generally, no gain or loss is recognized until the entire depletion base is sold. However, gain or loss is recognized from the sale of less than an entire depletion base if the disposition is significant enough to materially impact the depletion rate of the remaining properties in the depletion base. Ordinary maintenance and repair costs are expensed as incurred.
	Costs of significant nonproducing properties, wells in the process of being drilled and completed and development projects are excluded from depletion until the related project is completed and proved developed reserves are established or, if unsuccessful, impairment is determined. The Company capitalizes interest, if debt is outstanding, on expenditures for significant development projects until such projects are ready for their intended use. The Company had capitalized interest of $1.4 million during 2014. The Company did not capitalize interest during 2013 or 2012.
	The Company reviews its long-lived assets to be held and used, including proved oil and natural gas properties, whenever events or circumstances indicate that the carrying value of those assets may not be recoverable. An impairment loss is indicated if the sum of the expected future cash flows is less than the carrying amount of the assets. In this circumstance, the Company recognizes an impairment loss for the amount by which the carrying amount of the asset exceeds the estimated fair value of the asset. The Company reviews its oil and natural gas properties by depletion base or by individual well for those wells not constituting part of a depletion base. For each property determined to be impaired, an impairment loss equal to the difference between the carrying value of the properties and the estimated fair value (discounted future cash flows) of the properties would be recognized at that time. Estimating future cash flows involves the use of judgments, including estimation of the proved and risk-adjusted unproved oil and natural gas reserve quantities, timing of development and production, expected future commodity prices, capital expenditures and production costs. The Company recognized impairment expense of $447.2 million and $65.4 million during the years ended December 31, 2014 and 2013, respectively, related to its proved oil and natural gas properties. The Company did not recognize impairment expense related to its long-lived assets for the year ended December 31, 2012.
	Unproved oil and natural gas properties are each periodically assessed for impairment by considering future drilling plans, the results of exploration activities, commodity price outlooks, planned future sales or expiration of all or a portion of such projects. During the years ended December 31, 2014, 2013 and 2012, the Company recognized expense of $217.3 million, $49.8 million and $12.4 million, respectively, related to abandoned prospects and expiring acreage, which is included in exploration and abandonments expense in the accompanying consolidated statements of operations.
Other property and equipment	Other property and equipment.  Other capital assets include buildings, transportation equipment, computer equipment and software, telecommunications equipment, leasehold improvements and furniture and fixtures. These items are recorded at cost, or fair value if acquired, and are depreciated using the straight-line method based on expected lives of the individual assets or group of assets ranging from two to 31 years. The Company had other capital assets of $129.1 million and $114.8 million, net of accumulated depreciation of $52.5 million and $39.2 million, at December 31, 2014 and December 31, 2013, respectively. During the years ended December 31, 2014, 2013 and 2012, the Company recognized depreciation expense of $17.3 million, $15.2 million and $12.4 million, respectively.
Intangible assets.	Intangible assets. The Company has capitalized certain operating rights acquired in an acquisition. The gross operating rights, which have no residual value, are amortized over the estimated economic life of 25 years. Impairment will be assessed if indicators of potential impairment exist or when there is a material change in the remaining useful economic life. The following table reflects the gross and net intangible assets at December 31, 2014 and 2013, respectively:
				December 31,
	(in thousands)			2014			2013
	Gross intangible - operating rights		$	36,557		$	36,557
	Accumulated amortization			-9,403			-7,942
		Net intangible - operating rights	$	27,154		$	28,615
	The following table reflects amortization expense from continuing and discontinued operations for the years ended December 31, 2014, 2013 and 2012:
			Years Ending December 31,
	(in thousands)		2014			2013		2012
	Amortization expense		$	1,461		$	1,461	$	1,549
	The following table reflects the estimated aggregate amortization expense for each of the periods presented below at December 31, 2014:
	(in thousands)
	2015		$	1,461
	2016			1,461
	2017			1,461
	2018			1,461
	2019			1,461
	Thereafter			19,849
		Total	$	27,154
Equity method investment	Equity method investment. The Company owns a 50 percent member interest in a midstream joint venture, Alpha Crude Connector, LLC (“ACC”), to construct a crude oil gathering and transportation system in the northern Delaware Basin. The Company accounts for its investment in ACC under the equity method of accounting for investments in unconsolidated affiliates. The Company’s net investment in ACC is $29.5 million at December 31, 2014 and is included in other assets in the Company’s consolidated balance sheet. The equity loss for the period since inception is approximately $1.3 million and is included in other expense in the Company’s consolidated statement of operations. During 2014, the Company recorded $0.7 million of capitalized interest on the investment in ACC.
Environmental	Environmental. The Company is subject to extensive federal, state and local environmental laws and regulations. These laws, which are often changing, regulate the discharge of materials into the environment and may require the Company to remove or mitigate the environmental effects of the disposal or release of petroleum or chemical substances at various sites. Environmental expenditures are expensed. Expenditures that relate to an existing condition caused by past operations and that have no future economic benefits are expensed. Liabilities for expenditures of a noncapital nature are recorded when environmental assessment and/or remediation is probable and the costs can be reasonably estimated. Such liabilities are generally undiscounted unless the timing of cash payments is fixed and readily determinable. At December 31, 2014 and 2013, the Company has accrued approximately $1.7 million and $2.3 million, respectively, related to environmental liabilities. During the years ended December 31, 2014, 2013 and 2012, the Company recognized environmental charges of $4.0 million, $3.4 million and $4.4 million, respectively.
Derivative instruments	Derivative instruments. The Company recognizes its derivative instruments, other than any commodity derivative contracts that are designated as normal purchase and normal sale, as either assets or liabilities measured at fair value. The Company netted the fair value of derivative instruments by counterparty in the accompanying consolidated balance sheets where the right of offset exists. The Company did not have any derivatives designated as fair value or cash flow hedges during the years ended December 31, 2014, 2013 or 2012. The Company may also enter into physical delivery contracts to effectively provide commodity price hedges. Because these contracts are not expected to be net cash settled, they are considered to be normal sales contracts and not derivatives. Therefore, these contracts are not recorded in the Company’s consolidated financial statements.
Asset retirement obligations	Asset retirement obligations. The Company records the fair value of a liability for an asset retirement obligation in the period in which it is incurred and a corresponding increase in the carrying amount of the related long-lived asset. Subsequently, the asset retirement cost included in the carrying amount of the related asset is allocated to expense through depletion of the asset. Changes in the liability due to passage of time are generally recognized as an increase in the carrying amount of the liability and as corresponding accretion expense.
Treasury stock	Treasury stock. Treasury stock purchases are recorded at cost. Upon reissuance, the cost of treasury shares held is reduced by the average purchase price per share of the aggregate treasury shares held.
Revenue recognition	Revenue recognition. Oil and natural gas revenues are recorded at the time of physical transfer of such products to the purchaser, which for the Company is primarily at the wellhead. The Company follows the sales method of accounting for oil and natural gas sales, recognizing revenues based on the Company’s actual proceeds from the oil and natural gas sold to purchasers.
Oil and natural gas imbalances	Oil and natural gas imbalances. Oil and natural gas imbalances are generated on properties for which two or more owners have the right to take production “in-kind” and, in doing so, take more or less than their respective entitled percentage. Imbalances are tracked by well, but the Company does not record any receivable from or payable to the other owners unless the imbalance has reached a level at which it exceeds the remaining reserves in the respective well. If reserves are insufficient to offset the imbalance and the Company is in an overtake position, a liability is recorded for the amount of shortfall in reserves valued at a contract price or the market price in effect at the time the imbalance is generated. If the Company is in an undertake position, a receivable is recorded for an amount that is reasonably expected to be received, not to exceed the current market value of such imbalance. The Company had no significant imbalances at December 31, 2014 or 2013.
General and administrative expense.	General and administrative expense. The Company receives fees for the operation of jointly-owned oil and natural gas properties and records such reimbursements as reductions of general and administrative expense. Such fees from continuing and discontinued operations totaled approximately $23.2 million, $18.5 million and $16.8 million for the years ended December 31, 2014, 2013 and 2012, respectively.
Stock-based compensation	Stock-based compensation. For stock-based compensation awards granted, stock-based compensation expense is being recognized in the Company's financial statements on an accelerated basis over the awards' vesting periods based on their fair values on the dates of grant. The stock-based compensation awards generally vest over a period ranging from one to five years. The Company utilizes (i) the Black-Scholes option pricing model to measure the fair value of stock options, (ii) the average of the grant date’s high and low stock prices for the fair value of restricted stock and (iii) the Monte Carlo simulation method for the fair value of performance unit awards.
Income taxes	Income taxes. The Company recognizes deferred tax assets and liabilities for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rate is recognized in income in the period that includes the enactment date. A valuation allowance is established to reduce deferred tax assets if it is more likely than not that the related tax benefits will not be realized.
Income taxes uncertainties	The Company evaluates uncertain tax positions for recognition and measurement in the consolidated financial statements. To recognize a tax position, the Company determines whether it is more likely than not that the tax positions will be sustained upon examination, including resolution of any related appeals or litigation, based on the technical merits of the position. A tax position that meets the more likely than not threshold is measured to determine the amount of benefit to be recognized in the consolidated financial statements. The amount of tax benefit recognized with respect to any tax position is measured as the largest amount of benefit that is greater than 50 percent likely of being realized upon settlement. The Company had no material uncertain tax positions that required recognition in the consolidated financial statements at December 31, 2014 and 2013. Any interest or penalties would be recognized as a component of income tax expense.
Recent accounting pronouncements	Recent accounting pronouncements. In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” that outlines a new, single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. This new revenue recognition model provides a five-step analysis in determining when and how revenue is recognized. The new model will require revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration a company expects to receive in exchange for those goods or services.
	An entity is required to apply ASU 2014-09 for annual reporting periods beginning after December 15, 2016, and interim periods within those annual periods. An entity can apply ASU 2014-09 using either a full retrospective method, meaning the standard is applied to all of the periods presented, or a modified retrospective method, meaning the cumulative effect of initially applying the standard is recognized in the most current period presented in the financial statements. The Company is evaluating the impact that this new guidance will have on its consolidated financial statements.
	In April 2014, the FASB issued ASU No. 2014-08, “Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity (Topics 205 and 360),” that raises the threshold for a disposal to qualify as a discontinued operation and requires new disclosures of both discontinued operations and certain other disposals that do not meet the definition of a discontinued operation. Under the revised standard, a discontinued operation is (i) a component of an entity or group of components that has been disposed of by sale, disposed of other than by sale or is classified as held for sale that represents a strategic shift that has or will have a major effect on an entity’s operations and financial results or (ii) an acquired business or nonprofit activity that is classified as held for sale on the date of the acquisition. This update is aimed at reducing the frequency of disposals reported as discontinued operations by focusing on strategic shifts that have or will have a major effect on an entity’s operations and financial results.
	An entity is required to apply ASU 2014-08 for annual reporting periods beginning on or after December 15, 2014, and interim periods within those annual periods, though earlier adoption is permitted. An entity should provide the disclosures required by this amendment prospectively. The Company does not expect this guidance to have a significant impact on the consolidated financial statements.

Summary_of_significant_account2

Summary of significant accounting policies (Tables)	12 Months Ended
	Dec. 31, 2014
Accounting Policies [Abstract]
Schedule of Noncash or Part Noncash Divestitures [Table Text Block]	The Company made the following divestiture of assets during the period covered by these consolidated financial statements:
	(dollars in millions)
	Date divested					Dec-12
	Net proceeds				$	503.1
	Gain on disposition of assets				$	0.9
Schedule of Finite-Lived Intangible Assets [Table Text Block]	The following table reflects the gross and net intangible assets at December 31, 2014 and 2013, respectively:
				December 31,
	(in thousands)			2014			2013
	Gross intangible - operating rights		$	36,557		$	36,557
	Accumulated amortization			-9,403			-7,942
		Net intangible - operating rights	$	27,154		$	28,615
Schedule Of Amortization Expense [Table Text Block]	The following table reflects amortization expense from continuing and discontinued operations for the years ended December 31, 2014, 2013 and 2012:
			Years Ending December 31,
	(in thousands)		2014			2013		2012
	Amortization expense		$	1,461		$	1,461	$	1,549
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	The following table reflects the estimated aggregate amortization expense for each of the periods presented below at December 31, 2014:
	(in thousands)
	2015		$	1,461
	2016			1,461
	2017			1,461
	2018			1,461
	2019			1,461
	Thereafter			19,849
		Total	$	27,154

Exploratory_well_costs_Tables

Exploratory well costs (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure Exploratory Well Costs Capitalized Exploratory Well Activity [Abstract]
Company's capitalized exploratory well activity	The following table reflects the Company’s net capitalized exploratory well activity during each of the years ended December 31, 2014, 2013 and 2012:
			Years Ended December 31,
	(in thousands)		2014		2013		2012
	Beginning capitalized exploratory well costs		$	144,504	$	118,806	$	107,767
		Additions to exploratory well costs pending the determination of proved reserves		234,057		130,967		112,529
		Reclassifications due to determination of proved reserves		-99,657		-94,114		-99,514
		Exploratory well costs charged to expense		-37,247		-11,155		-1,976
	Ending capitalized exploratory well costs		$	241,657	$	144,504	$	118,806
Aging of capitalized exploratory well costs based on the date drilling was completed	The following table provides an aging at December 31, 2014 and 2013 of capitalized exploratory well costs based on the date drilling was completed:
				December 31,
	(dollars in thousands)			2014		2013
	Capitalized exploratory well costs that have been capitalized for a period of one year or less		$	232,346	$	122,753
	Capitalized exploratory well costs that have been capitalized for a period greater than one year			9,311		21,751
		Total capitalized exploratory well costs	$	241,657	$	144,504
	Number of projects with exploratory well costs that have been capitalized for a period greater
		than one year		7		10

Asset_retirement_obligations_T

Asset retirement obligations (Tables)	12 Months Ended
	Dec. 31, 2014
Asset Retirement Obligation Disclosure [Abstract]
Asset retirement obligations	The Company’s asset retirement obligation transactions during the years ended December 31, 2014, 2013 and 2012 are summarized in the table below:
			Years Ended December 31,
	(in thousands)			2014		2013		2012
	Asset retirement obligations, beginning of period		$	101,593	$	86,261	$	59,685
		Liabilities incurred from new wells		5,324		6,338		7,729
		Liabilities assumed in acquisitions		4,065		593		29,113
		Accretion expense for continuing operations		7,072		6,047		4,187
		Accretion expense for discontinued operations		-		-		1,004
		Disposition of wells		-		-		-24,614
		Liabilities settled upon plugging and abandoning wells		-2,926		-3,447		-1,261
		Revision of estimates		4,753		5,801		10,418
	Asset retirement obligations, end of period		$	119,881	$	101,593	$	86,261

Incentive_plans_Tables

Incentive plans (Tables)	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of the Company's restricted stock awards activity	A summary of the Company’s restricted stock award activity for the years ended December 31, 2014, 2013 and 2012 is presented below:
								Weighted
								Average
					Number of			Grant Date
					Restricted			Fair Value
					Shares			Per Share
	Restricted stock:
		Outstanding at January 1, 2012			912,013
			Shares granted		470,633		$	98.31
			Shares cancelled / forfeited		-58,727
			Lapse of restrictions		-251,392
		Outstanding at December 31, 2012			1,072,527
			Shares granted		498,468		$	88.19
			Shares cancelled / forfeited		-118,472
			Lapse of restrictions		-236,074
		Outstanding at December 31, 2013			1,216,449
			Shares granted		448,730		$	129.12
			Shares cancelled / forfeited		-89,401
			Lapse of restrictions		-484,469
		Outstanding at December 31, 2014			1,091,309
Summarizes information about stock-based compensation for the Company's restricted stock awards activity under the Plan	The following table summarizes information about stock-based compensation for the Company’s restricted stock awards activity under the Plan for years ended December 31, 2014, 2013 and 2012:
					Years Ended December 31,
	(in thousands)					2014			2013			2012
	Grant date fair value for awards during the period (a)				$	57,940		$	44,947		$	46,268
	Stock-based compensation expense from restricted stock				$	36,585		$	30,984		$	29,685
	Income taxes and other information:
		Income tax benefit related to restricted stock			$	13,672		$	11,650		$	11,349
		Deductions in current taxable income related to restricted stock vestings			$	58,908		$	20,883		$	23,570
	(a) The year ended December 31, 2013 includes the effects of $1 million due to modifications of certain stock-based awards.
Summary of the Company's stock option awards activity under the Plan	Stock option awards.  A summary of the Company’s stock option award activity under the Plan for the years ended December 31, 2014, 2013 and 2012 is presented below:
					Years Ended December 31,
					2014					2013					2012
								Weighted					Weighted				Weighted
								Average					Average				Average
					Number of			Exercise		Number of			Exercise		Number of		Exercise
					Options			Price		Options			Price		Options		Price
	Stock options:
		Outstanding at beginning of period			255,537		$	21.5		429,879		$	20.28		930,178	$	18.1
			Options exercised		-207,824		$	22.42		-174,342		$	18.48		-500,299	$	16.24
		Outstanding at end of period			47,713		$	17.49		255,537		$	21.5		429,879	$	20.28
		Vested and exercisable at end of period			47,713		$	17.49		255,537		$	21.5		403,077	$	20.24
Summarizes information about the Company's vested and exercisable stock options outstanding	The following table summarizes information about the Company’s vested and exercisable stock options outstanding at December 31, 2014:
								Weighted
								Average			Weighted			Intrinsic
			Range of					Remaining			Average			Value
			Exercise			Number		Contractual			Exercise			of
			Prices			Vested		Life			Price			Options
														(in thousands)
	December 31, 2014:
		Vested and exercisable options:
			$12.00			5,636		0.91 years		$	12		$	495
			$12.50 - $15.50			15,000		2.62 years		$	12.85			1,304
			$20.00 - $23.00			27,077		3.98 years		$	21.2			2,127
						47,713		3.19 years		$	17.49		$	3,926
Summarizes information about stock-based compensation for stock options	The following table summarizes information about stock-based compensation for stock options for the years ended December 31, 2014, 2013 and 2012:
				Years Ended December 31,
	(in thousands)					2014			2013			2012
	Stock-based compensation expense from stock options				$	-		$	14		$	187
	Income taxes and other information:
		Income tax benefit related to stock options			$	-		$	6		$	72
		Deductions in current taxable income related to stock options exercised			$	23,208		$	13,193		$	39,828
Summarizes the assumptions to estimate the fair value of performance units granted	The Company used the following assumptions to estimate the fair value of performance unit awards granted during the years ended December 31, 2014 and 2013:
					Years Ended December 31,
					2014			2013
	Risk-free interest rate				0.76%			0.37%
	Range of volatilities				29.2% - 42.2%			31.5% - 45.1%
Summary of the Company's performance unit activity	The following table summarizes the performance unit activity for the years ended December 31, 2014 and 2013:
						Number of			Grant Date
						Units (a)			Fair Value
	Performance units:
		Outstanding at December 31, 2012				-
			Units granted			110,889		$	111.4
		Outstanding at December 31, 2013				110,889
			Units granted			139,425		$	139.54
		Outstanding at December 31, 2014				250,314
	(a)	Reflects the amount of performance units granted. The actual payout of shares will be between zero and 300 percent of the performance units granted depending on the Company's performance at the end of the performance period.
Summarizes information about stock-based compensation for the Company's performance unit awards activity under the Plan	The following table summarizes information about stock-based compensation expense for performance units for the years ended December 31, 2014 and 2013:
					Years Ended December 31,
	(in thousands)					2014			2013
	Grant date fair value for awards during the period				$	19,455		$	12,352
	Stock-based compensation expense from performance units				$	10,545		$	4,080
	Income tax benefit related to performance units				$	3,941		$	1,560
Future stock-based compensation expense to be recorded for all the stock-based compensation awards that were outstanding	Future stock-based compensation expense. The following table reflects the future stock-based compensation expense to be recorded for all the stock-based compensation awards that were outstanding at December 31, 2014:
					Restricted			Performance
	(in thousands)				Stock			Units			Total
	2015			$	30,290		$	10,668		$	40,958
	2016				18,819			6,514			25,333
	2017				7,066			-			7,066
	2018				851			-			851
	2019				3			-			3
		Total		$	57,029		$	17,182		$	74,211

Disclosures_about_fair_value_o1

Disclosures about fair value of financial instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Carrying amounts and fair values of the Company's financial instruments	The following table presents the carrying amounts and fair values of the Company’s financial instruments at December 31, 2014 and 2013:
					31-Dec-14						31-Dec-13
					Carrying			Fair			Carrying			Fair
	(in thousands)				Value			Value			Value			Value
		Assets:
			Derivative instruments		$	752,700		$	752,700		$	1,556		$	1,556
		Liabilities:
			Derivative instruments		$	-		$	-		$	67,789		$	67,789
			Credit facility		$	139,500		$	131,068		$	250,000		$	250,770
			7.0% senior notes due 2021		$	600,000		$	625,500		$	600,000		$	660,000
			6.5% senior notes due 2022		$	600,000		$	628,500		$	600,000		$	649,500
			5.5% senior notes due 2022		$	600,000		$	598,500		$	600,000		$	619,500
			5.5% senior notes due 2023		$	1,577,820		$	1,573,875		$	1,580,421		$	1,627,834
Net basis derivative fair values as reported in the consolidated balance sheets	The following tables summarize (i) the valuation of each of the Company’s financial instruments by required fair value hierarchy levels and (ii) the gross fair value by the appropriate balance sheet classification, even when the derivative instruments are subject to netting arrangements and qualify for net presentation in the Company’s consolidated balance sheets at December 31, 2014 and 2013. The Company nets the fair value of derivative instruments by counterparty in the Company’s consolidated balance sheets.
	31-Dec-14
						Fair Value Measurements Using															Net
						Quoted Prices													Gross		Fair Value
						in Active					Significant								Amounts		Presented
						Markets for					Other			Significant					Offset in the		in the
						Identical					Observable			Unobservable					Consolidated		Consolidated
						Assets					Inputs			Inputs			Total		Balance		Balance
	(in thousands)					(Level 1)					(Level 2)			(Level 3)			Fair Value		Sheet		Sheet
		Assets
			Current:
				Commodity derivatives			$	-		$	501,717		$	-		$	501,717	$	-11,366	$	490,351
			Noncurrent:
				Commodity derivatives				-			262,349			-			262,349		-		262,349
		Liabilities
			Current:
				Commodity derivatives				-			-11,366			-			-11,366		11,366		-
			Noncurrent:
				Commodity derivatives				-			-			-			-		-		-
		Net derivative instruments					$	-		$	752,700		$	-		$	752,700	$	-	$	752,700
	31-Dec-13
						Fair Value Measurements Using															Net
						Quoted Prices													Gross		Fair Value
						in Active					Significant								Amounts		Presented
						Markets for					Other			Significant					Offset in the		in the
						Identical					Observable			Unobservable					Consolidated		Consolidated
						Assets					Inputs			Inputs			Total		Balance		Balance
	(in thousands)					(Level 1)					(Level 2)			(Level 3)			Fair Value		Sheet		Sheet
		Assets
			Current:
				Commodity derivatives			$	-		$	12,819		$	-		$	12,819	$	-12,229	$	590
			Noncurrent:
				Commodity derivatives				-			5,300			-			5,300		-4,334		966
		Liabilities
			Current:
				Commodity derivatives				-			-65,930			-			-65,930		12,229		-53,701
			Noncurrent:
				Commodity derivatives				-			-18,422			-			-18,422		4,334		-14,088
		Net derivative instruments					$	-		$	-66,233		$	-		$	-66,233	$	-	$	-66,233
Carrying amounts, estimated fair values and impairment expense of long-lived assets	The following table reports the carrying amount, estimated fair value and impairment expense of long-lived assets for the indicated periods:
							Estimated
				Carrying			Fair Value			Impairment
	(in thousands)			Amount			(Level 3)			Expense
	Dec-14		$	677,021		$	245,346		$	431,675
	Sep-14		$	26,790		$	11,314		$	15,476
	Jun-13		$	84,140		$	18,765		$	65,375

Derivative_financial_instrumen1

Derivative financial instruments (Tables)	12 Months Ended
	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Summarizes the gains and losses reported in earnings related to the commodity and interest rate derivative instruments	The following table summarizes the gains and losses reported in earnings related to the commodity derivative instruments for the years ended December 31, 2014, 2013 and 2012:
				Years Ended December 31,
	(in thousands)				2014			2013			2012
	Gain (loss) on derivatives not designated as hedges:
		Oil derivatives		$	869,421		$	-133,890		$	127,293
		Natural gas derivatives			21,496			10,238			150
			Total	$	890,917		$	-123,652		$	127,443
	The following table represents the Company's cash receipts from (payments on) derivatives reported in the Company's cash flows from investing for the years ended December 31, 2014, 2013 and 2012:
				Years Ended December 31,
	(in thousands)				2014			2013			2012
	Cash receipts from (payments on) derivatives not designated as hedges:
		Oil derivatives		$	76,335		$	-41,616		$	22,411
		Natural gas derivatives			-4,352			9,275			1,125
			Total	$	71,983		$	-32,341		$	23,536
Company's outstanding derivative contracts	Commodity derivative contracts at December 31, 2014. The following table sets forth the Company’s outstanding derivative contracts at December 31, 2014. When aggregating multiple contracts, the weighted average contract price is disclosed. All of the Company’s derivative contracts at December 31, 2014 are expected to settle by June 30, 2017.
					First		Second		Third		Fourth
					Quarter		Quarter		Quarter		Quarter		Total
	Oil Swaps: (a)
		2015:00:00
			Volume (Bbl)		4,240,000		3,919,000		3,654,000		3,449,000		15,262,000
			Price per Bbl	$	88.32	$	87.5	$	87.57	$	87.42	$	87.73
		2016:00:00
			Volume (Bbl)		3,218,000		3,068,000		2,958,000		105,000		9,349,000
			Price per Bbl	$	90.43	$	90.9	$	90.46	$	88.28	$	90.57
		2017:00:00
			Volume (Bbl)		84,000		84,000		-		-		168,000
			Price per Bbl	$	87	$	87	$	-	$	-	$	87
	Oil Basis Swaps: (b)
		2015:00:00
			Volume (Bbl)		3,915,000		3,836,500		3,634,000		3,404,000		14,789,500
			Price per Bbl	$	-3.47	$	-3.45	$	-3.44	$	-3.38	$	-3.44
	Natural Gas Swaps: (c)
		2015:00:00
			Volume (MMBtu)		5,850,000		5,915,000		5,980,000		5,980,000		23,725,000
			Price per MMBtu	$	4.16	$	4.16	$	4.16	$	4.16	$	4.16
	Natural Gas Basis Swaps: (d)
		2015:00:00
			Volume (MMBtu)		1,350,000		1,365,000		1,380,000		1,380,000		5,475,000
			Price per MMBtu	$	-0.13	$	-0.13	$	-0.13	$	-0.13	$	-0.13
	(a) The index prices for the oil price swaps are based on the NYMEX – West Texas Intermediate (“WTI”) monthly average futures price.
	(b) The basis differential price is between Midland – WTI and Cushing – WTI.
	(c) The index prices for the natural gas price swaps are based on the NYMEX – Henry Hub last trading day futures price.
	(d) The basis differential price is between the El Paso Permian delivery point and NYMEX – Henry Hub delivery point.

Debt_Tables

Debt (Tables)	12 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Company's debt	Note 8. Debt
	The Company’s debt consists of the following at December 31, 2014 and 2013:
						December 31,
	(in thousands)					2014			2013
	Credit facility				$	139,500		$	250,000
	7.0% unsecured senior notes due 2021					600,000			600,000
	6.5% unsecured senior notes due 2022					600,000			600,000
	5.5% unsecured senior notes due 2022					600,000			600,000
	5.5% unsecured senior notes due 2023					1,550,000			1,550,000
	Unamortized original issue premium (discount), net					27,820			30,421
		Less: current portion				-			-
			Total long-term debt		$	3,517,320		$	3,630,421
Future interest expense from the 2017 Senior Notes original issue discount	Future benefit to interest expense from original issue premium at December 31, 2014 was as follows:
	(in thousands)
	2015			$		2,747
	2016					2,900
	2017					3,062
	2018					3,233
	2019					3,413
	Thereafter					12,465
		Total		$		27,820
Principal maturities of debt	Principal maturities of long-term debt. Principal maturities of long-term debt outstanding at December 31, 2014 are as follows:
	(in thousands)
	2015			$		-
	2016					-
	2017					-
	2018					-
	2019					139,500
	Thereafter					3,350,000
		Total		$		3,489,500
Interest expense	Interest expense. The following amounts have been incurred and charged to interest expense for the years ended December 31, 2014, 2013 and 2012:
							Years Ended December 31,
	(in thousands)							2014			2013		2012
	Cash payments for interest						$	211,342		$	200,961	$	158,715
	Amortization of original issue discount (premium)							-2,599			-1,248		462
	Amortization of deferred loan origination costs							10,937			13,172		11,958
	Net changes in accruals							-737			5,696		11,570
		Interest costs incurred						218,943			218,581		182,705
	Less: capitalized interest							-2,282			-		-
		Total interest expense					$	216,661		$	218,581	$	182,705

Commitments_and_contingencies_

Commitments and contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Summary of the Company's future drilling commitments	Commitments. The Company periodically enters into contractual arrangements under which the Company is committed to expend funds. The following table summarizes the Company’s commitments at December 31, 2014:
		Payments Due By Period
	(in thousands)		Total			2015		2016		2017		2018		2019		Thereafter
	Purchase obligations (a)	$	167,174		$	57,489	$	30,017	$	15,080	$	21,077	$	7,606	$	35,905
	(a) Relates to purchase agreements we have entered into including daywork drilling contracts, water commitment agreements, throughput volume delivery commitments and power commitments.
	____________________________________________________________________________________
Future minimum lease commitments under non-cancellable operating leases	Future minimum lease commitments under non-cancellable operating leases at December 31, 2014 are as follows:
	(in thousands)
	2015			$	7,245
	2016				5,589
	2017				5,577
	2018				4,787
	2019				4,112
	Thereafter				8,905
		Total		$	36,215

Income_taxes_Tables

Income taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
The Company's income tax provision	Income tax provision. The Company’s income tax provision and amounts separately allocated were attributable to the following items for the years ended December 31, 2014, 2013 and 2012:
							Years Ended December 31,
	(in thousands)							2014			2013		2012
	Income from continuing operations						$	317,785		$	118,237	$	251,041
	Income from discontinued operations							-			7,518		14,519
	Changes in stockholders' equity:
		Excess tax benefits related to stock-based compensation						-16,480			-6,147		-18,963
							$	301,305		$	119,608	$	246,597
Company's income tax provision attributable to income from continuing operations	The Company’s income tax provision attributable to income from continuing operations consisted of the following for the years ended December 31, 2014, 2013 and 2012:
							Years Ended December 31,
	(in thousands)							2014			2013		2012
	Current:
		U.S. federal					$	16,621		$	12,504	$	7,066
		U.S. state and local						4,997			3,306		2,156
			Total current income tax provision					21,618			15,810		9,222
	Deferred:
		U.S. federal						278,615			119,985		210,527
		U.S. state and local						17,552			-17,558		31,292
			Total deferred income tax provision					296,167			102,427		241,819
				Total income tax provision attributable to income from
					continuing operations		$	317,785		$	118,237	$	251,041
reconciliation between the income tax expense computed by multiplying pretax income from continuing operations	The reconciliation between the income tax expense computed by multiplying pretax income from continuing operations by the United States federal statutory rate and the reported amounts of income tax expense from continuing operations is as follows:
							Years Ended December 31,
	(in thousands)							2014			2013		2012
	Income at U.S. federal statutory rate						$	299,586		$	125,006	$	230,745
	State income taxes (net of federal tax effect)							22,826			12,505		21,192
	Revisions of previous estimates							738			1,400		219
	Change in estimated effective statutory state income tax							-7,945			-21,876		-
	Nondeductible expense & other							2,580			1,202		-1,115
		Income tax expense					$	317,785		$	118,237	$	251,041
	Effective tax rate							37.10%			33.10%		38.10%
Company's income tax provision attributable to income from discontinued operations	The Company’s income tax provision attributable to income from discontinued operations consisted of the following for the years ended December 31, 2013 and 2012:
							Years Ended December 31,
	(in thousands)							2013			2012
	Current:
		U.S. federal					$	144		$	14,023
		U.S. state and local						25			1,667
			Total current income tax expense					169			15,690
	Deferred:
		U.S. federal						6,397			-1,392
		U.S. state and local						952			221
			Total deferred income tax provision					7,349			-1,171
				Total income tax provision attributable to income from discontinued operations			$	7,518		$	14,519
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities were as follows:
						December 31,
	(in thousands)					2014				2013
	Deferred tax assets:
		Stock-based compensation				$	24,810		$	23,262
		Derivative instruments					-			24,904
		Asset retirement obligation					44,802			38,241
		Other					24,368			9,500
				Total deferred tax assets			93,980			95,907
	Deferred tax liabilities:
		Oil and natural gas properties, principally due to differences in basis and
			depreciation and the deduction of intangible drilling costs for tax purposes				-1,396,756			-1,383,929
		Intangible assets - operating rights					-10,148			-10,759
		Derivative instruments					-281,303			-
		Other					-6,524			-5,803
				Total deferred tax liability			-1,694,731			-1,400,491
				Net deferred tax liability		$	-1,600,751		$	-1,304,584

Major_customers_and_derivative1

Major customers and derivative counterparties (Tables)	12 Months Ended
	Dec. 31, 2014
Major Customer Disclosure [Abstract]
Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]	The following purchasers individually accounted for 10 percent or more of the consolidated oil and natural gas revenues, including the revenues from discontinued operations, during the years ended December 31, 2014, 2013 and 2012:
			Years Ended December 31,
			2014	2013	2012
	Holly Frontier Refining and Marketing, LLC		17%	30%	26%
	Enterprise Crude Oil LLC		12%	13%	6%
	Western Refining Company LP		12%	1%	-
	Phillips 66		8%	6%	14%
Schedule of Derivative Instruments Counterparties Fair Value [Table Text Block]	At December 31, 2014, the Company had a net asset position of $752.7 million as a result of outstanding derivative contracts from the following counterparties:
	(in thousands)
	J.P. Morgan Chase Bank	$	134,735
	Wells Fargo Bank, N.A.		84,523
	Barclays Bank PLC		81,979
	Bank of Montreal		59,789
	KeyBank National Association		59,702
	Citibank, N.A.		55,826
	Canadian Imperial Bank of Commerce		48,466
	Merrill Lynch Commodities, Inc.		46,738
	Union Bank, N.A.		33,986
	Natixis		32,874
	ING Capital Markets LLC		30,496
	Other		83,586
	Total	$	752,700

Related_party_transactions_Tab

Related party transactions (Tables)	12 Months Ended
	Dec. 31, 2014
Related Party Transactions [Abstract]
Summary of charges incurred with and payments made to the Company's related parties and reported in the consolidated statements of operations, as well as outstanding payables included in the consolidated balance sheets	The following table summarizes payments made to related parties and reported in the Company’s consolidated statements of operations for the periods presented:
		Years Ended December 31,
	(in thousands)		2014		2013		2012
	Amounts paid to a partnership in which a director has an ownership interest (a)	$	15,181	$	7,255	$	2,444
	Royalties paid to a director and certain officers of the Company (b)	$	383	$	43	$	77
	Amounts paid under consulting agreement with Steven L. Beal (c)	$	-	$	865	$	251
	Amounts include royalties on certain properties and lease bonus payments paid to a partnership in which a director of the Company is the general partner and owns a 3.5 percent partnership interest.
	Payments made to a director and certain officers (or affiliated entities) who own revenue, overriding royalty interests or net profits interests in properties owned by the Company.
	On June 30, 2009, Steven L. Beal, the Company’s then-president and chief operating officer, retired from such positions. On June 9, 2009, the Company entered into a consulting agreement (the “Consulting Agreement”) with Mr. Beal, under which Mr. Beal began serving as a consultant to the Company on July 1, 2009. During the term of the consulting relationship, Mr. Beal received a consulting fee of $20,000 per month and a monthly reimbursement for his medical and dental coverage costs. In August 2013, the Company and Mr. Beal mutually terminated the Consulting Agreement in exchange for the payment to Mr. Beal of $720,000, which termination and payment were approved by the disinterested members of the Company’s Board of Directors.

Discontinued_operations_Tables

Discontinued operations (Tables)	12 Months Ended
	Dec. 31, 2014
Discontinued Operations and Disposal Groups [Abstract]
Components of the Company's discontinued operations	The following table represents the components of the Company’s discontinued operations for the years ended December 31, 2013 and 2012:
				Years Ended December 31,
	(in thousands)			2013		2012
	Operating revenues:
		Oil sales		$	-	$	101,359
		Natural gas sales			-		18,578
			Total operating revenues		-		119,937
	Operating costs and expenses:
		Oil and natural gas production			-		34,270
		Exploration and abandonments			-		334
		Depreciation, depletion and amortization (a)			-		30,140
		Accretion of discount on asset retirement obligations (a)			-		1,004
		General and administrative (b)			-		-2,493
			Total operating costs and expenses		-		63,255
	Income from operations				-		56,682
	Other income (expense):
		Gain (loss) on disposition of assets, net (a)			19,599		-18,704
	Income from discontinued operations before income taxes				19,599		37,978
	Income tax benefit (expense):
		Current			-169		-15,690
		Deferred (a)			-7,349		1,171
	Income from discontinued operations, net of tax			$	12,081	$	23,459
	(a)		Represents the significant non-cash components of discontinued operations.
	(b)		Represents the fees received from third-parties for operating oil and natural gas properties that were sold. The Company reflects these fees as a reduction of general and administrative expenses.

Net_income_per_share_Tables

Net income per share (Tables)	12 Months Ended
	Dec. 31, 2014
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Reconciliation of earnings attributable to common shares, basic and diluted	The following tables reconcile the Company’s income from continuing operations, income from discontinued operations and net income attributable to common stockholders to the basic and diluted earnings used to determine the Company’s income per share amounts for the years ended December 31, 2014, 2013 and 2012, respectively, under the two-class method:
						Year Ended
						31-Dec-14
					Continuing			Discontinued
	(in thousands, except per share amounts)				Operations			Operations		Total
	Income as reported				$	538,175		$	-	$	538,175
	Participating basic earnings					-5,961			-		-5,961
		Basic income attributable to common stockholders				532,214			-		532,214
	Reallocation of participating earnings					16			-		16
		Diluted income attributable to common stockholders			$	532,230		$	-	$	532,230
	Income per common share:
		Basic			$	4.89		$	-	$	4.89
		Diluted			$	4.88		$	-	$	4.88
						Year Ended
						31-Dec-13
					Continuing			Discontinued
	(in thousands, except per share amounts)				Operations			Operations		Total
	Income as reported				$	238,922		$	12,081	$	251,003
	Participating basic earnings					-2,610			-132		-2,742
		Basic income attributable to common stockholders				236,312			11,949		248,261
	Reallocation of participating earnings					4			-		4
		Diluted income attributable to common stockholders			$	236,316		$	11,949	$	248,265
	Income per common share:
		Basic			$	2.28		$	0.11	$	2.39
		Diluted			$	2.28		$	0.11	$	2.39
						Year Ended
						31-Dec-12
					Continuing			Discontinued
	(in thousands, except per share amounts)				Operations			Operations		Total
	Income as reported				$	408,230		$	23,459	$	431,689
	Participating basic earnings					-			-		-
		Basic income attributable to common stockholders				408,230			23,459		431,689
	Reallocation of participating earnings					-			-		-
		Diluted income attributable to common stockholders			$	408,230		$	23,459	$	431,689
	Income per common share:
		Basic			$	3.96		$	0.22	$	4.18
		Diluted			$	3.93		$	0.22	$	4.15
reconciliation of the basic weighted average common shares outstanding to diluted weighted average common shares outstanding	The following table is a reconciliation of the basic weighted average common shares outstanding to diluted weighted average common shares outstanding for the years ended December 31, 2014, 2013 and 2012:
					Years Ended December 31,
	(in thousands)				2014		2013		2012
	Weighted average common shares outstanding:
		Basic			108,844		103,744		103,190
			Dilutive common stock options		83		165		354
			Dilutive restricted stock		-		-		428
			Dilutive performance units		205		4		-
		Diluted			109,132		103,913		103,972
summary of the common stock options and restricted stock which were not included in the computation of diluted net income per share	The following table is a summary of the restricted stock and performance units, which were not included in the computation of diluted net income per share, as inclusion of these items would be antidilutive:
				Years Ended December 31,
	(in thousands)			2014		2013		2012
	Number of antidilutive common shares:
		Antidilutive restricted stock		153		9		95
		Antidilutive performance units		-		83		-

Other_current_liabilities_Tabl

Other current liabilities (Tables)	12 Months Ended
	Dec. 31, 2014
Other Liabilities Disclosure [Abstract]
components of the Company's other current liabilities	The following table provides the components of the Company’s other current liabilities at December 31, 2014 and 2013:
					December 31,
	(in thousands)				2014		2013
	Other current liabilities:
		Accrued production costs		$	70,786	$	48,196
		Payroll related matters			34,349		28,498
		Accrued interest			69,264		70,000
		Asset retirement obligations			9,146		4,481
		Other			11,763		5,425
			Other current liabilities	$	195,308	$	156,600

Subsidiary_guarantors_Tables

Subsidiary guarantors (Tables)	12 Months Ended
	Dec. 31, 2014
Guarantees [Abstract]
Condensed Consolidating Balance Sheet	Condensed Consolidating Balance Sheet
	31-Dec-14
					Parent			Subsidiary			Consolidating
	(in thousands)				Issuer			Guarantors			Entries			Total
	ASSETS
	Accounts receivable - related parties			$	6,670,744		$	1,201,950		$	-7,872,694		$	-
	Other current assets				569,545			618,851			-			1,188,396
	Oil and natural gas properties, net				-			10,076,878			-			10,076,878
	Property and equipment, net				-			129,136			-			129,136
	Investment in subsidiaries				4,085,045			-			-4,085,045			-
	Other long-term assets				330,792			74,761			-			405,553
		Total assets		$	11,656,126		$	12,101,576		$	-11,957,739		$	11,799,963
	LIABILITIES AND EQUITY
	Accounts payable - related parties			$	1,201,950		$	6,670,744		$	-7,872,694		$	-
	Other current liabilities				217,884			1,209,309			-			1,427,193
	Long-term debt				3,517,320			-			-			3,517,320
	Other long-term liabilities				1,438,184			136,478			-			1,574,662
	Equity				5,280,788			4,085,045			-4,085,045			5,280,788
		Total liabilities and equity		$	11,656,126		$	12,101,576		$	-11,957,739		$	11,799,963
	Condensed Consolidating Balance Sheet
	31-Dec-13
					Parent			Subsidiary			Consolidating
	(in thousands)				Issuer			Guarantors			Entries			Total
	ASSETS
	Accounts receivable - related parties			$	6,115,554		$	1,261,844		$	-7,377,398		$	-
	Other current assets				39,108			481,767			-			520,875
	Oil and natural gas properties, net				-			8,831,265			-			8,831,265
	Property and equipment, net				-			114,783			-			114,783
	Investment in subsidiaries				3,896,741			-			-3,896,741			-
	Other long-term assets				74,013			50,228			-			124,241
		Total assets		$	10,125,416		$	10,739,887		$	-11,274,139		$	9,591,164
	LIABILITIES AND EQUITY
	Accounts payable - related parties			$	1,261,844		$	6,115,554		$	-7,377,398		$	-
	Other current liabilities				126,461			630,407			-			756,868
	Long-term debt				3,630,421			-			-			3,630,421
	Other long-term liabilities				1,348,741			97,185			-			1,445,926
	Equity				3,757,949			3,896,741			-3,896,741			3,757,949
		Total liabilities and equity		$	10,125,416		$	10,739,887		$	-11,274,139		$	9,591,164
Condensed Consolidating Statement of Operations	Condensed Consolidating Statement of Operations
	For the Year Ended December 31, 2014
					Parent			Subsidiary			Consolidating
	(in thousands)				Issuer			Guarantors			Entries			Total
	Total operating revenues			$	-		$	2,660,147		$	-		$	2,660,147
	Total operating costs and expenses				888,632			-2,459,034			-			-1,570,402
		Income from operations			888,632			201,113			-			1,089,745
	Interest expense				-216,661			-			-			-216,661
	Loss on extinguishment of debt				-4,316			-			-			-4,316
	Other, net				188,305			-12,809			-188,304			-12,808
		Income before income taxes			855,960			188,304			-188,304			855,960
	Income tax expense				-317,785			-			-			-317,785
		Net income		$	538,175		$	188,304		$	-188,304		$	538,175
	Condensed Consolidating Statement of Operations
	For the Year Ended December 31, 2013
				Parent			Subsidiary			Consolidating
	(in thousands)			Issuer			Guarantors			Entries			Total
	Total operating revenues			$	-		$	2,319,919		$	-		$	2,319,919
	Total operating costs and expenses				-125,924			-1,576,558			-			-1,702,482
		Income (loss) from operations			-125,924			743,361			-			617,437
	Interest expense				-218,581			-			-			-218,581
	Loss on extinguishment of debt				-28,616			-			-			-28,616
	Other, net				749,878			-13,136			-749,823			-13,081
		Income before income taxes			376,757			730,225			-749,823			357,159
	Income tax expense				-118,237			-			-			-118,237
		Income from continuing operations			258,520			730,225			-749,823			238,922
	Income (loss) from discontinued operations, net of tax				-7,517			19,598			-			12,081
		Net income		$	251,003		$	749,823		$	-749,823		$	251,003
	Condensed Consolidating Statement of Operations
	For the Year Ended December 31, 2012
						Parent			Subsidiary			Subsidiary			Consolidating
	(in thousands)					Issuer			Guarantors			Non-Guarantor			Entries			Total
	Total operating revenues				$	-		$	1,812,472		$	7,342		$	-		$	1,819,814
	Total operating costs and expenses					126,482			-1,090,013			-5,720			-			-969,251
		Income from operations				126,482			722,459			1,622			-			850,563
	Interest expense					-182,705			-			-			-			-182,705
	Other, net					753,472			-3,148			-6,043			-752,868			-8,587
		Income (loss) before income taxes				697,249			719,311			-4,421			-752,868			659,271
	Income tax expense					-251,041			-			-			-			-251,041
		Income (loss) from continuing operations				446,208			719,311			-4,421			-752,868			408,230
	Income (loss) from discontinued operations,
		net of tax				-14,519			37,978			-			-			23,459
		Net income (loss)			$	431,689		$	757,289		$	-4,421		$	-752,868		$	431,689
Condensed Consolidating Statement of Cash Flows	Condensed Consolidating Statement of Cash Flows
	For the Year Ended December 31, 2014
					Parent Issuer			Subsidiary Guarantors			Consolidating Entries
	(in thousands)													Total
	Net cash flows provided by (used in) operating activities			$	-888,369		$	2,562,156		$	-		$	1,673,787
	Net cash flows provided by (used in) investing activities				71,983			-2,617,979			-			-2,545,996
	Net cash flows provided by financing activities				816,386			55,823			-			872,209
		Net decrease in cash and cash equivalents			-			-			-			-
		Cash and cash equivalents at beginning of period			-			21			-			21
		Cash and cash equivalents at end of period		$	-		$	21		$	-		$	21
	Condensed Consolidating Statement of Cash Flows
	For the Year Ended December 31, 2013
					Parent			Subsidiary			Consolidating
	(in thousands)				Issuer			Guarantors			Entries			Total
	Net cash flows provided by (used in) operating activities			$	-487,131		$	1,849,151		$	-		$	1,362,020
	Net cash flows used in investing activities				-32,341			-1,864,453			-			-1,896,794
	Net cash flows provided by financing activities				519,472			12,443			-			531,915
		Net decrease in cash and cash equivalents			-			-2,859			-			-2,859
		Cash and cash equivalents at beginning of period			-			2,880			-			2,880
		Cash and cash equivalents at end of period		$	-		$	21		$	-		$	21
	Condensed Consolidating Statement of Cash Flows
	For the Year Ended December 31, 2012
							Parent			Subsidiary			Subsidiary			Consolidating
	(in thousands)						Issuer			Guarantors			Non-Guarantor			Entries			Total
	Net cash flows provided by (used in)
		operating activities				$	-1,044,006		$	2,278,647		$	2,837		$	-		$	1,237,478
	Net cash flows provided by (used in)
		investing activities					23,536			-1,720,242			-543,738			-			-2,240,444
	Net cash flows provided by (used in)
		financing activities					1,020,470			-555,867			540,901			-			1,005,504
			Net increase in cash and cash
				equivalents			-			2,538			-			-			2,538
			Cash and cash equivalents at
				beginning of period			-			342			-			-			342
			Cash and cash equivalents at
				end of period		$	-		$	2,880		$	-		$	-		$	2,880

Subsequent_events_Tables

Subsequent events (Tables)	12 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
New commodity derivative contracts
					First		Second		Third		Fourth
					Quarter		Quarter		Quarter		Quarter		Total
	Oil Swaps: (a)
		2015:00:00
			Volume (Bbl)		-		660,000		660,000		660,000		1,980,000
			Price per Bbl	$	-	$	56.6	$	56.6	$	56.6	$	56.6
		2016:00:00
			Volume (Bbl)		180,000		180,000		180,000		2,610,000		3,150,000
			Price per Bbl	$	61.04	$	61.04	$	61.04	$	62.48	$	62.23
	Oil Basis Swaps: (b)
		2016:00:00
			Volume (Bbl)		364,000		364,000		368,000		368,000		1,464,000
			Price per Bbl	$	-2.48	$	-2.48	$	-2.48	$	-2.48	$	-2.48
	(a)		The index prices for the oil price swaps are based on the NYMEX – WTI monthly average futures price.
	(b)		The basis differential price is between Midland – WTI and Cushing – WTI.

Recovered_Sheet1

Summary Of Significant Accounting Policies (Narrative) (Detail) (USD $)	3 Months Ended			12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Summary Of Significant Accounting Policies Narrative [Abstract]
Allowance for Doubtful Accounts Receivable	$700,000			$700,000	$700,000
Deferred loan costs	68,443,000			68,443,000	73,048,000
Accumulated amortization				59,700,000	48,700,000
Estimated economic life of gross operating rights in years				25 years
Depletion expense from continuing and discontuned operations				960,900,000	756,000,000	591,300,000
Impairment Of Oil And Gas Properties	431,675,000	15,476,000	65,375,000	447,151,000	65,375,000	0
Impairment of Leasehold				217,300,000	49,800,000	12,400,000
Other property and equipment, net	129,136,000			129,136,000	114,783,000
Other property and equipment, accumulated depreciation	52,500,000			52,500,000	39,200,000
Depreciation expense on other property and equipment				17,300,000	15,200,000	12,400,000
Environmental liability accrued	1,700,000			1,700,000	2,300,000
Environmental libility recognized				4,000,000	3,400,000	4,400,000
Fees related to operation of jointly owned oil and natural gas properties				23,200,000	18,500,000	16,800,000
Equity method investment ownership percentage	50.00%			50.00%
Total equity method investment	29,500,000			29,500,000
Income (loss) from equity method investments				-1,300,000
Interest costs capitalized on oil and gas properties				1,400,000	0	0
Interest costs capitalized on equity method investment				$700,000

Recovered_Sheet2

Summary Of Significant Accounting Policies (Discontinued Operations) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Gain on Sale of Assets	$0.90
Disposal Date	15-Dec-12
Net Proceeds	$503.10

Recovered_Sheet3

Summary Of Significant Accounting Policies (Gross And Net Intangible Assets) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Disclosure Summary Of Significant Accounting Policies Gross And Net Intangible Assets [Abstract]
Gross intangible - operating rights	$36,557	$36,557
Accumulated amortization	-9,403	-7,942
Net intangible - operating rights	$27,154	$28,615

Summary_Of_Significant_Account3

Summary Of Significant Accounting Policies (Amortization Expense) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Summary Of Significant Accounting Policies Amortization Expense [Abstract]
Amortization expense	$1,461	$1,461	$1,549

Summary_Of_Significant_Account4

Summary Of Significant Accounting Policies (Estimated Future Aggregate Amortization Expense) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Disclosure Summary Of Significant Accounting Policies Estimated Future Aggregate Amortization Expense [Abstract]
2015	$1,461
2016	1,461
2017	1,461
2018	1,461
2019	1,461
Thereafter	19,849
Net intangible - operating rights	$27,154	$28,615

Exploratory_Well_Costs_Capital

Exploratory Well Costs (Capitalized Exploratory Well Activity) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Exploratory Well Costs Capitalized Exploratory Well Activity [Abstract]
Beginning capitalized exploratory well costs	$144,504	$118,806	$107,767
Additions to exploratory well costs pending the determination of proved reserves	234,057	130,967	112,529
Reclassifications due to determination of proved reserves	-99,657	-94,114	-99,514
Exploratory well costs charged to expense	-37,247	-11,155	-1,976
Ending capitalized exploratory well costs	$241,657	$144,504	$118,806

Exploratory_Well_Costs_Aging_O

Exploratory Well Costs (Aging Of Capitalized Exploratory Well Costs Based On The Date Of Drilling) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
In Thousands, unless otherwise specified	Number	Number
Disclosure Exploratory Well Costs Aging Of Capitalized Exploratory Well Costs Based On The Date Of Drilling [Abstract]
Capitalized exploratory well costs that have been capitalized for a period of one year or less	$232,346	$122,753
Capitalized exploratory well costs that have been capitalized for a period greater than one year	9,311	21,751
Total capitalized exploratory well costs	$241,657	$144,504	$118,806	$107,767
Projects that have Exploratory Well Costs that have been Capitalized for Period Greater than One Year, Number of Projects	7	10

Exploratory_Well_Costs_Narrati

Exploratory Well Costs (Narrative) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Oil And Gas In Process Activities [Line Items]
Capitalized Exploratory Well Costs That Have Been Capitalized For Period Greater Than One Year	$9,311	$21,751
Other Projects [Member]
Oil And Gas In Process Activities [Line Items]
Capitalized Exploratory Well Costs That Have Been Capitalized For Period Greater Than One Year	3,000
OBO Projects [Member]
Oil And Gas In Process Activities [Line Items]
Capitalized Exploratory Well Costs That Have Been Capitalized For Period Greater Than One Year	$6,300

Asset_Retirement_Obligations_S

Asset Retirement Obligations (Schedule Of Asset Retirement Obligation Transactions) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Asset Retirement Obligations Schedule Of Asset Retirement Obligation Transactions [Abstract]
Asset retirement obligations, beginning of period	$101,593	$86,261	$59,685
Liabilities incurred from new wells	5,324	6,338	7,729
Liabilities assumed in acquisitions	4,065	593	29,113
Accretion expense for continuing operations	7,072	6,047	4,187
Accretion expense for discontinued operations	0	0	1,004
Disposition of wells	0	0	-24,614
Liabilities settled upon plugging and abandoning wells	-2,926	-3,447	-1,261
Revision of estimates	4,753	5,801	10,418
Asset retirement obligations, end of period	$119,881	$101,593	$86,261

Incentive_Plans_Narrative_Deta

Incentive Plans (Narrative) (Detail) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, employers contribution	$8.10	$6.60	$5.30
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$23.20	$13.20	$39.80
Performance unit awards vesting period	3 years
Approved and authorized awards	7,500,000
Awards available for future grant	823,975
Plan 401 k [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan employer's contribution match percentage	100.00%
Defined contribution plan, employee contribution	10.00%

Incentive_Plans_Schedule_Of_Re

Incentive Plans (Schedule Of Restricted Stock Awards Activity) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Incentive Plans Schedule Of Restricted Stock Awards Activity [Abstract]
Outstanding at beginning of period	1,216,449	1,072,527	912,013
Shares granted	448,730	498,468	470,633
Shares cancelled / forfeited	-89,401	-118,472	-58,727
Lapse of restrictions	-484,469	-236,074	-251,392
Outstanding at end of period	1,091,309	1,216,449	1,072,527
Shares Granted - Grant Date Value Per Share	$129.12	$88.19	$98.31

Incentive_Plans_Summary_Inform

Incentive Plans (Summary Information For Stock-Based Compensation For Restricted Stock Awards) (Detail) (Restricted Stock [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant date fair value for awards during the period	$57,940	$44,947	[1]	$46,268
Stock-based compensation expense from restricted stock	36,585	30,984		29,685
Income tax benefit related to restricted stock	13,672	11,650		11,349
Deductions in current taxable income related to restricted stock vestings	$58,908	$20,883		$23,570
[1]	The year ended December 31, 2013 includes the effects of $1 million due to modifications of certain stock-based awards.

Incentive_Plans_Schedule_Of_St

Incentive Plans (Schedule Of Stock Option Awards Activity) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Incentive Plans Schedule Of Stock Option Awards Activity [Abstract]
Outstanding at beginning of period (Shares)	255,537	429,879	930,178
Options exercised (Shares)	-207,824	-174,342	-500,299
Outstanding at end of period (Shares)	47,713	255,537	429,879
Vested and exercisable at end of period (Shares)	47,713
Outstanding at beginning of period	$21.50	$20.28	$18.10
Options exercised	$22.42	$18.48	$16.24
Outstanding at end of period	$17.49	$21.50	$20.28
Vested and exercisable at end of period - weighted average exercise price	$17.49	$21.50	$20.24

Incentive_Plans_Summary_Inform1

Incentive Plans (Summary Information For Vested And Exercisable Stock Options Outstanding) (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Vested and exercisable at end of period (Shares)	47,713
Weighted Average Remaining Contractual Life, Vested and exercisable options, years	3 years 2 months
Vested and exercisable at end of period - weighted average exercise price	$17.49	$21.50	$20.24
Intrinsic Value, Vested and exercisable options	$3,926	$22,103	$24,313
Range Two [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise price	$12
Vested and exercisable at end of period (Shares)	5,636
Weighted Average Remaining Contractual Life, Vested and exercisable options, years	0 years 11 months
Vested and exercisable at end of period - weighted average exercise price	$12	$12	$12
Intrinsic Value, Vested and exercisable options	495	1,496	2,805
Range Three [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise price, Lower range	$12.50
Exercise price, Upper range	$15.50
Vested and exercisable at end of period (Shares)	15,000
Weighted Average Remaining Contractual Life, Vested and exercisable options, years	2 years 7 months
Vested and exercisable at end of period - weighted average exercise price	$12.85	$12.85	$14.91
Intrinsic Value, Vested and exercisable options	1,304	1,427	5,088
Range Four [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise price, Lower range	$20
Exercise price, Upper range	$23
Vested and exercisable at end of period (Shares)	27,077
Weighted Average Remaining Contractual Life, Vested and exercisable options, years	3 years 12 months
Vested and exercisable at end of period - weighted average exercise price	$21.20	$21.40	$21.57
Intrinsic Value, Vested and exercisable options	$2,127	$16,705	$12,369

Incentive_Plans_Summary_Inform2

Incentive Plans (Summary Information For Stock-Based Compensation For Stock Options) (Detail) (Stock Options [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense from stock options	$0	$14	$187
Income tax benefit related to stock options	0	6	72
Deductions in current taxable income related to stock options exercised	$23,208	$13,193	$39,828

Incentive_Plans_Summary_Of_Ass

Incentive Plans (Summary Of Assumptions To Estimate Fair Value of Performance Unit Awards) (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Disclosure Incentive Plans Schedule Of Performance Unit Awards Fair Value Assumptions [Abstract]
Risk-free interest rate	0.76%	0.37%
Volatility assumption - minimum	29.20%	31.50%
Volatility assumption - maximum	42.20%	45.10%

Incentive_Plans_Schedule_Of_Pe

Incentive Plans (Schedule Of Performance Unit Awards Activity) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Disclosure Incentive Plans Schedule Of Performance Unit Awards Activity [Abstract]
Performance units outstanding at beginning of period (Shares)	110,889	[1]	0	[1]
Units granted	139,425	[1]	110,889	[1]
Performance units outstanding at end of period (Shares)	250,314	[1]	110,889	[1]
Shares Granted - Grant Date Fair Value - Performance Units	$139.54		$111.40
[1]	Reflects the amount of performance units granted. The actual payout of shares will be between zero and 300 percent of the performance units granted depending on the Company's performance at the end of the performance period.

Incentive_Plans_Summary_Inform3

Incentive Plans (Summary Information For Stock-Based Compensation For Performance Units) (Detail) (Performance Shares [Member], USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Performance Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant date fair value for awards during the period	$19,455	$12,352
Allocated Share Based Compensation Expense	10,545	4,080
Employee Service Share Based Compensation Tax Benefit From Compensation Expense	$3,941	$1,560

Incentive_Plans_Summary_For_Fu

Incentive Plans (Summary For Future Stock-Based Compensation Expense) (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
2015	$40,958
2016	25,333
2017	7,066
2018	851
2019	3
Total	74,211
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
2015	30,290
2016	18,819
2017	7,066
2018	851
2019	3
Total	57,029
Performance Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
2015	10,668
2016	6,514
2017	0
2018	0
2019	0
Total	$17,182

Recovered_Sheet4

Disclosures About Fair Value Of Financial Instruments (Carrying Amounts And Fair Values Of The Company's Financial Instruments) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Credit facility	$139,500	$250,000
Seven Point Zero Percent Unsecured Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	600,000	600,000
Six Point Five Percent Unsecured Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	600,000	600,000
Five Point Five Percent Unsecured Senior Notes Due Twenty Twenty Three [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	1,550,000	1,550,000
Carrying Reported Amount Fair Value Disclosure [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative instruments, Assets	752,700	1,556
Derivative instruments, Liabilities	0	67,789
Credit facility	139,500	250,000
Carrying Reported Amount Fair Value Disclosure [Member] | Seven Point Zero Percent Unsecured Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	600,000	600,000
Carrying Reported Amount Fair Value Disclosure [Member] | Six Point Five Percent Unsecured Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	600,000	600,000
Carrying Reported Amount Fair Value Disclosure [Member] | Five Piont Five Percent Unsecured Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	600,000	600,000
Carrying Reported Amount Fair Value Disclosure [Member] | Five Point Five Percent Unsecured Senior Notes Due Twenty Twenty Three [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	1,577,820	1,580,421
Portion At Fair Value Fair Value Disclosure [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative instruments, Assets	752,700	1,556
Derivative instruments, Liabilities	0	67,789
Credit facility	131,068	250,770
Portion At Fair Value Fair Value Disclosure [Member] | Seven Point Zero Percent Unsecured Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	625,500	660,000
Portion At Fair Value Fair Value Disclosure [Member] | Six Point Five Percent Unsecured Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	628,500	649,500
Portion At Fair Value Fair Value Disclosure [Member] | Five Piont Five Percent Unsecured Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	598,500	619,500
Portion At Fair Value Fair Value Disclosure [Member] | Five Point Five Percent Unsecured Senior Notes Due Twenty Twenty Three [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	$1,573,875	$1,627,834

Recovered_Sheet5

Disclosures About Fair Value Of Financial Instruments (Company's Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Current derivative contracts, assets	$490,351	$590
Noncurrent derivative contracts, assets	262,349	966
Current derivative contracts, liabilities	0	-53,701
Noncurrent derivative contracts, liabilities	0	-14,088
Net derivative instruments	752,700	-66,233
Fair Value Inputs Level 1 [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Current derivative contracts, assets	0	0
Noncurrent derivative contracts, assets	0	0
Current derivative contracts, liabilities	0	0
Noncurrent derivative contracts, liabilities	0	0
Net derivative instruments	0	0
Fair Value Inputs Level 2 [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Current derivative contracts, assets	501,717	12,819
Noncurrent derivative contracts, assets	262,349	5,300
Current derivative contracts, liabilities	-11,366	-65,930
Noncurrent derivative contracts, liabilities	0	-18,422
Net derivative instruments	752,700	-66,233
Fair Value Inputs Level 3 [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Current derivative contracts, assets	0	0
Noncurrent derivative contracts, assets	0	0
Current derivative contracts, liabilities	0	0
Noncurrent derivative contracts, liabilities	0	0
Net derivative instruments	0	0
Estimate Of Fair Value Fair Value Disclosure [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Current derivative contracts, assets	501,717	12,819
Noncurrent derivative contracts, assets	262,349	5,300
Current derivative contracts, liabilities	-11,366	-65,930
Noncurrent derivative contracts, liabilities	0	-18,422
Net derivative instruments	752,700	-66,233
Gross Amounts Offset in Consolidated Balance Sheet [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Current derivative contracts, assets	-11,366	-12,229
Noncurrent derivative contracts, assets	0	-4,334
Current derivative contracts, liabilities	11,366	12,229
Noncurrent derivative contracts, liabilities	0	4,334
Net derivative instruments	$0	$0

Disclosures_About_Fair_Value_O2

Disclosures About Fair Value Of Financial Instruments (Fair Value Derivative Instruments) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current:(b)
Fair value assets measured on recurring basis, derivative financial instruments assets, current	$490,351	$590
Noncurrent:(c)
Fair value assets measured on recurring basis, derivative financial instruments assets, noncurrent	262,349	966
Current:(b)
Fair value liabilities measured on recurring basis, derivative financial instruments liabilities, current	0	-53,701
Noncurrent:(c)
Fair value liabilities measured on recurring basis, derivative financial instruments liabilities, noncurrent	0	-14,088
Net financial assets (liabilities)	752,700	-66,233
Fair Value Inputs Level 1 [Member]
Current:(b)
Fair value assets measured on recurring basis, derivative financial instruments assets, current	0	0
Noncurrent:(c)
Fair value assets measured on recurring basis, derivative financial instruments assets, noncurrent	0	0
Current:(b)
Fair value liabilities measured on recurring basis, derivative financial instruments liabilities, current	0	0
Noncurrent:(c)
Fair value liabilities measured on recurring basis, derivative financial instruments liabilities, noncurrent	0	0
Net financial assets (liabilities)	0	0
Fair Value Inputs Level 2 [Member]
Current:(b)
Fair value assets measured on recurring basis, derivative financial instruments assets, current	501,717	12,819
Noncurrent:(c)
Fair value assets measured on recurring basis, derivative financial instruments assets, noncurrent	262,349	5,300
Current:(b)
Fair value liabilities measured on recurring basis, derivative financial instruments liabilities, current	-11,366	-65,930
Noncurrent:(c)
Fair value liabilities measured on recurring basis, derivative financial instruments liabilities, noncurrent	0	-18,422
Net financial assets (liabilities)	752,700	-66,233
Fair Value Inputs Level 3 [Member]
Current:(b)
Fair value assets measured on recurring basis, derivative financial instruments assets, current	0	0
Noncurrent:(c)
Fair value assets measured on recurring basis, derivative financial instruments assets, noncurrent	0	0
Current:(b)
Fair value liabilities measured on recurring basis, derivative financial instruments liabilities, current	0	0
Noncurrent:(c)
Fair value liabilities measured on recurring basis, derivative financial instruments liabilities, noncurrent	0	0
Net financial assets (liabilities)	0	0
Estimate Of Fair Value Fair Value Disclosure [Member]
Current:(b)
Fair value assets measured on recurring basis, derivative financial instruments assets, current	501,717	12,819
Noncurrent:(c)
Fair value assets measured on recurring basis, derivative financial instruments assets, noncurrent	262,349	5,300
Current:(b)
Fair value liabilities measured on recurring basis, derivative financial instruments liabilities, current	-11,366	-65,930
Noncurrent:(c)
Fair value liabilities measured on recurring basis, derivative financial instruments liabilities, noncurrent	0	-18,422
Net financial assets (liabilities)	$752,700	($66,233)

Disclosures_About_Fair_Value_O3

Disclosures About Fair Value Of Financial Instruments (Carrying Amounts, Estimated Fair Values And Impairment Expense Of Long-Lived Assets For Continuing And Discontinued Operations) (Detail) (USD $)	3 Months Ended			12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Disclosures About Fair Value Of Financial Instruments Carrying Amounts Estimated Fair Values And Impairment Expense Of Long Lived Assets For Continuing And Discontinued Operations [Abstract]
Carrying Amount	$677,021	$26,790	$84,140
Estimated Fair Value	245,346	11,314	18,765
Impairment Expense	$431,675	$15,476	$65,375	$447,151	$65,375	$0

Recovered_Sheet6

Derivative Financial Instruments (Gains And Losses Reported In Earnings Related To The Commodity And Interest Rate Derivative Instruments) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative Financial Instruments Gains And Losses Reported In Earnings Related To Commodity And Interest Rate Derivative Instruments [Line Items]
Cash (payments on) receipts from derivatives not designated as hedges	($71,983)	$32,341	($23,536)
Mark-to-market gain (loss)	890,917	-123,652	127,443
Oil Commodity Derivative [Member]
Derivative Financial Instruments Gains And Losses Reported In Earnings Related To Commodity And Interest Rate Derivative Instruments [Line Items]
Cash (payments on) receipts from derivatives not designated as hedges	76,335	-41,616	22,411
Mark-to-market gain (loss)	869,421	-133,890	127,293
Natural Gas Commodity Derivative [Member]
Derivative Financial Instruments Gains And Losses Reported In Earnings Related To Commodity And Interest Rate Derivative Instruments [Line Items]
Cash (payments on) receipts from derivatives not designated as hedges	-4,352	9,275	1,125
Mark-to-market gain (loss)	$21,496	$10,238	$150

Recovered_Sheet7

Derivative Financial Instruments (Outstanding Commodity Derivative Contracts) (Detail)	3 Months Ended								12 Months Ended
	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2015
	bbl		bbl		bbl		bbl		bbl
Oil Swaps [Member]
Derivative [Line Items]
Volume (Bbl/MMBtu) - Current Year	3,449,000	[1]	3,654,000	[1]	3,919,000	[1]	4,240,000	[1]	15,262,000	[1]
Price per Bbl/MMBtu - Current Year	87.42	[1]	87.57	[1]	87.5	[1]	88.32	[1]	87.73	[1]
Volume (Bbl/MMBtu) - Year One	105,000	[1]	2,958,000	[1]	3,068,000	[1]	3,218,000	[1]	9,349,000	[1]
Price per Bbl/MMBtu - Year One	88.28	[1]	90.46	[1]	90.9	[1]	90.43	[1]	90.57	[1]
Volume (Bbl/MMBtu) - Year Two	0	[1]	0	[1]	84,000	[1]	84,000	[1]	168,000	[1]
Price per Bbl/MMBtu - Year Two	0	[1]	0	[1]	87	[1]	87	[1]	87	[1]
Oil Basis Swaps [Member]
Derivative [Line Items]
Volume (Bbl/MMBtu) - Current Year	3,404,000	[2]	3,634,000	[2]	3,836,500	[2]	3,915,000	[2]	14,789,500	[2]
Price per Bbl/MMBtu - Current Year	-3.38	[2]	-3.44	[2]	-3.45	[2]	-3.47	[2]	-3.44	[2]
Natural Gas Swap [Member]
Derivative [Line Items]
Volume (Bbl/MMBtu) - Current Year	5,980,000	[3]	5,980,000	[3]	5,915,000	[3]	5,850,000	[3]	23,725,000	[3]
Price per Bbl/MMBtu - Current Year	4.16	[3]	4.16	[3]	4.16	[3]	4.16	[3]	4.16	[3]
Natural Gas Basis Swap [Member]
Derivative [Line Items]
Volume (Bbl/MMBtu) - Current Year	1,380,000	[4]	1,380,000	[4]	1,365,000	[4]	1,350,000	[4]	5,475,000	[4]
Price per Bbl/MMBtu - Current Year	-0.13	[4]	-0.13	[4]	-0.13	[4]	-0.13	[4]	-0.13	[4]
[1]	The index prices for the oil price swaps are based on the NYMEX b West Texas Intermediate monthly average futures price.
[2]	The basis differential price is between Midland b WTI and Cushing b WTI.
[3]	The index prices for the natural gas price swaps are based on the NYMEX b Henry Hub last trading day futures price.
[4]	The index prices for the natural gas collars are based on the El Paso Permian delivery point.

Debt_Summary_Of_LongTerm_Debt_

Debt (Summary Of Long-Term Debt) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Credit facility	$139,500,000	$250,000,000
Unamortized original issue premium (discount), net	27,820,000	30,421,000
Less: current portion	0	0
Total long-term debt	3,517,320,000	3,630,421,000
7.0% senior notes due 2021
Debt Instrument [Line Items]
Unsecured senior notes	600,000,000	600,000,000
6.5% senior notes due 2022
Debt Instrument [Line Items]
Unsecured senior notes	600,000,000	600,000,000
5.5% unsecured senior notes due 2022
Debt Instrument [Line Items]
Unsecured senior notes	600,000,000	600,000,000
5.5% unsecured senior notes due 2023
Debt Instrument [Line Items]
Unsecured senior notes	$1,550,000,000	$1,550,000,000

Debt_Narrative_Detail

Debt (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Debt Disclosure [Line Items]
Line of credit maturity date	9-May-19
Aggregate lender commitments	$2,500,000,000
Aggregate maximum borrowing base	3,250,000,000
Unused lender commitments	2,400,000,000
Additional borrowings actually available	1,600,000,000
Line of credit interest rate	3.25%
Debt Related Commitment Fees and Debt Issuance Costs	7,700,000	8,300,000	6,300,000
Loss on extinguishment of debt	-4,316,000	-28,616,000	0
Minimum [Member]
Debt Disclosure [Line Items]
Commitment fees on unused portion of available commitment fee	0.30%
Maximum [Member]
Debt Disclosure [Line Items]
Commitment fees on unused portion of available commitment fee	0.38%
Prime Rate [Member] | Minimum [Member]
Debt Disclosure [Line Items]
Line Of Credit Facility Interest Rate At Period End	0.25%
Prime Rate [Member] | Maximum [Member]
Debt Disclosure [Line Items]
Line Of Credit Facility Interest Rate At Period End	1.25%
Eurodollar Future [Member] | Minimum [Member]
Debt Disclosure [Line Items]
Line Of Credit Facility Interest Rate At Period End	1.25%
Eurodollar Future [Member] | Maximum [Member]
Debt Disclosure [Line Items]
Line Of Credit Facility Interest Rate At Period End	2.25%
Same-Day Advance Facility
Debt Disclosure [Line Items]
Aggregate maximum borrowing base	25,000,000
Credit facility interest rate description	The interest rate on this facility is the JPM Prime Rate plus the applicable interest margin.
8.625% senior notes due 2017
Debt Disclosure [Line Items]
Debt Instrument, Repurchased Face Amount	225,600,000
Percentage Of Notes Tendered	75.20%
Price Of Tender And Consent	106.92%
Price Of Remaining Notes Tendered	106.52%
Loss on extinguishment of debt	28,600,000
Premium Paid For Tender Offer	20,400,000
Unamortized Debt Issuance Expense	5,500,000
Debt Instrument, Unamortized Discount	2,700,000
5.5% unsecured senior notes due 2023
Debt Disclosure [Line Items]
Debt instrument amount issued	850,000,000
Interest rate	5.50%
Debt Instrument Maturity Year	2023
Resulting Yield	4.88%
Proceeds from Debt, Net of Issuance Costs	$867,800,000

Debt_Future_Interest_Expense_F

Debt (Future Interest Expense From Original Issue Discount On Senior Notes) (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Disclosure Debt Future Interest Expense From Original Issue Discount On Senior Notes [Abstract]
2015	$2,747
2016	2,900
2017	3,062
2018	3,233
2019	3,413
Thereafter	12,465
Total	$27,820

Debt_Principal_Maturities_Of_D

Debt (Principal Maturities Of Debt) (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Disclosure Debt Principal Maturities Of Debt [Abstract]
2015	$0
2016	0
2017	0
2018	0
2019	139,500
Thereafter	3,350,000
Total	$3,489,500

Debt_Summary_Of_Interest_Expen

Debt (Summary Of Interest Expense) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Debt Summary Of Interest Expense [Abstract]
Cash payments for interest	$211,342	$200,961	$158,715
Amortization of original issue discount (premium)	-2,599	-1,248	462
Amortization of deferred loan origination costs	10,937	13,172	11,958
Net changes in accruals	-737	5,696	11,570
Interest costs incurred	218,943	218,581	182,705
Less: capitalized interest	-2,282	0	0
Total interest expense	$216,661	$218,581	$182,705

Recovered_Sheet8

Commitments And Contingencies (Narrative) (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Commitments [Line Items]
Annual officers' salaries	$7.40
Operating leases, lease payments	7.2	5.7	4.7
Accrued Exposure	$12.30	$12.20

Commitments_And_Contingencies_1

Commitments And Contingencies (Future Purchase Obligations) (Detail) (USD $)	Dec. 31, 2014
Disclosure Commitments And Contingencies Future Purchase Obligations [Abstract]
Total	$167,174,000	[1]
2015	57,489,000	[1]
2016	30,017,000	[1]
2017	15,080,000	[1]
2018	21,077,000	[1]
2019	7,606,000	[1]
Thereafter	$35,905,000	[1]
[1]	Relates to purchase agreements we have entered into including daywork drilling contracts, water commitment agreements, throughput volume delivery commitments and power commitments.

Commitments_And_Contingencies_2

Commitments And Contingencies (Future Minimum Lease Commitments Under Non-Cancellable Operating Leases) (Detail) (USD $)	Dec. 31, 2014
In Thousands, unless otherwise specified
Disclosure Commitments And Contingencies Future Minimum Lease Commitments Under Non Cancellable Operating Leases [Abstract]
2015	$7,245
2016	5,589
2017	5,577
2018	4,787
2019	4,112
Thereafter	8,905
Total	$36,215

Income_Taxes_Narrative_Detail

Income Taxes (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Income Taxes Narrative [Abstract]
Income taxes receivable, current	$32,900,000	$10,700,000
Income taxes payable, current	1,100,000	1,700,000
Change in effective statutory state income tax	($7,945,000)	($21,876,000)	$0

Income_Taxes_Companys_Income_T

Income Taxes (Company's Income Tax Provision (Benefit)) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Income Taxes Companys Income Tax Provision Benefit [Abstract]
Income from continuing operations	$317,785	$118,237	$251,041
Income from discontinued operations		7,518	14,519
Excess tax benefits related to stock-based compensation	-16,480	-6,147	-18,963
Income Tax Expense Benefit Net Of Excess Tax Benefits, Total	$301,305	$119,608	$246,597

Income_Taxes_Income_Tax_Provis

Income Taxes (Income Tax Provision (Benefit) Attributable To Income (Loss) From Continuing Operations) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Income Taxes Income Tax Provision Benefit Attributable To Income Loss From Continuing Operations [Abstract]
U.S. federal	$16,621	$12,504	$7,066
U.S. state and local	4,997	3,306	2,156
Total current income tax provision	21,618	15,810	9,222
U.S. federal	278,615	119,985	210,527
U.S. state and local	17,552	-17,558	31,292
Total deferred income tax provision	296,167	102,427	241,819
Total income tax provision attributable to income from continuing operations	$317,785	$118,237	$251,041

Income_Taxes_Reconciliation_Be

Income Taxes (Reconciliation Between The Income Tax Expense (Benefit) And The Reported Amounts Of Income Tax Expense) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Income Taxes Reconciliation Between The Income Tax Expense Benefit And The Reported Amounts Of Income Tax Expense [Abstract]
Income at U.S. federal statutory rate	$299,586	$125,006	$230,745
State income taxes (net of federal tax effect)	22,826	12,505	21,192
Revision of previous estimates	738	1,400	219
Change in effective statutory state income tax	-7,945	-21,876	0
Nondeductible expense & other	2,580	1,202	-1,115
Total income tax provision attributable to income from continuing operations	$317,785	$118,237	$251,041
Effective tax rate	37.10%	33.10%	38.10%

Income_Taxes_Companys_Income_T1

Income Taxes (Company's Income Tax Provision Attributable To Income From Discontinued Operations) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Disclosure Income Taxes Companys Income Tax Provision Attributable To Income From Discontinued Operations [Abstract]
U.S. federal, current	$144	$14,023
U.S. state and local, current	25	1,667
Total current income tax benefit	169	15,690
U.S. federal, deferred	6,397	-1,392
U.S. state and local, deferred	952	221
Total deferred income tax provision	7,349	-1,171
Total income tax provision attributable to income from discontinued operations	$7,518	$14,519

Income_Taxes_Deferred_Tax_Asse

Income Taxes (Deferred Tax Assets and Liabilities) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Components of Deferred Tax Assets and Liabilities [Abstract]
Stock Based Compensation	$24,810	$23,262
Derivative Instruments	0	24,904
Asset retirement obligation	44,802	38,241
Other	24,368	9,500
Total Deferred tax assets	-93,980	-95,907
Oil and Gas Properties deduction of intangible drilling cost due to tax purpose	1,396,756	1,383,929
Intangible Assets - Operating rights	10,148	10,759
Derivative instruments	281,303	0
Other	6,524	5,803
Deferred Tax Liabilities, Gross	1,694,731	1,400,491
Net deferred tax liabilities	($1,600,751)	($1,304,584)

Recovered_Sheet9

Major Customers and Derivative Counterparties (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Holly Frontier Refining and Marketing LLC [Member]
Revenue, Major Customer [Line Items]
Major Customer Percentage	17.00%	30.00%	26.00%
Entity Wide Receivables Major Customer	$48,600,000
Enterprise Crude Oil LLC [Member]
Revenue, Major Customer [Line Items]
Major Customer Percentage	12.00%	13.00%	6.00%
Entity Wide Receivables Major Customer	23,000,000
Western Refining Company LP [Member]
Revenue, Major Customer [Line Items]
Major Customer Percentage	12.00%	1.00%	0.00%
Entity Wide Receivables Major Customer	$19.30
Phillips 66 [Member]
Revenue, Major Customer [Line Items]
Major Customer Percentage	8.00%	6.00%	14.00%

Derivative_Counterparties_Deta

Derivative Counterparties (Detail) (USD $)	Dec. 31, 2014
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	$752,700,000
JP Morgan Chase Bank [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	134,735,000
Wells Fargo Bank NA [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	84,523,000
Barclays Bank PLC [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	81,979,000
Bank of Montreal [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	59,789,000
KeyBank National Association [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	59,702,000
Citibank NA [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	55,826,000
Canadian Imperial Bank of Commerce [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	48,466,000
Merrill Lynch Commodities Inc [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	46,738,000
Union Bank NA [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	33,986,000
Natixis [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	32,874,000
ING Capital Markets LLC [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	30,496,000
Other [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	$83,586,000

Related_Party_Transactions_Sch

Related Party Transactions (Schedule Of Related Party Transactions) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Related Party Transaction [Line Items]
Royalty interests of a director of the Company	$0		$0
Ownership interest in system	3.50%
Partnership (Director Ownership Interest) [Member]
Related Party Transaction [Line Items]
Royalty interest paid	15,181,000	[1]	7,255,000	[1]	2,444,000	[1]
Director And Certain Officers [Member]
Related Party Transaction [Line Items]
Royalty interest paid	383,000	[2]	43,000	[2]	77,000	[2]
Royalty interests of a director of the Company	0		0
Payments for Notes to Directors and Officers	1,300,000
Related party receivable from an officer (or affiliated entities)	76,000
Former President And Chief Operating Officer [Member]
Related Party Transaction [Line Items]
Amounts paid under consulting agreement with Steven L. Beal	0	[3]	865,000	[3]	251,000	[3]
Consulting fee per month	20,000
Payment To Mutually Terminate Consulting Agreement	$720,000
[1]	Amounts include royalties on certain properties and lease bonus payments paid to a partnership in which a director of the Company is the general partner and owns a 3.5 percent partnership interest.
[2]	Payments made to a director and certain officers (or affiliated entities) who own revenue, overriding royalty interests or net profits interests in properties owned by the Company.
[3]	On JuneB 30, 2009, Steven L. Beal, the Companybs then-president and chief operating officer, retired from such positions. On JuneB 9, 2009, the Company entered into a consulting agreement (the bConsulting Agreementb) with Mr.B Beal, under which Mr.B Beal began serving as a consultant to the Company on JulyB 1, 2009. During the term of the consulting relationship, Mr. Beal received a consulting fee of $20,000 per month and a monthly reimbursement for his medical and dental coverage costs. In August 2013, the Company and Mr. Beal mutually terminated the Consulting Agreement in exchange for the payment to Mr. Beal of $720,000, which termination and payment were approved by the disinterested members of the Companybs Board of Directors.

Discontinued_Operations_Narrat

Discontinued Operations (Narrative) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Approximate discontinued operation gain on disposition of assets	$0.90
Proceeds from Divestiture of Businesses	503.1
Adjustment to gain (loss) related to discontinued operations	$19.60

Discontinued_Operations_Schedu

Discontinued Operations (Schedule Of Discontinued Operations) (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disclosure Discontinued Operations Schedule Of Discontinued Operations [Abstract]
Oil sales		$0	$101,359
Natural gas sales		0	18,578
Total operating revenues		0	119,937
Oil and natural gas production		0	34,270
Exploration and Abandonments		0	334
Depreciation, depletion and amortization		0	30,140
Accretion of discount on asset retirement obligations		0	1,004
General and administrative		0	-2,493
Total operating costs and expenses		0	63,255
Income from operations		0	56,682
Gain on disposition of assets, net		19,599	-18,704
Income from discontinued operations before income taxes		19,599	37,978
Current		-169	-15,690
Deferred		-7,349	1,171
Income from discontinued operations, net of tax	$0	$12,081	$23,459

Net_Income_Per_Share_Reconcili

Net Income Per Share (Reconciliation Of Earnings Attributable To Common Shares Basic And Diluted) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Income (loss) as reported	$538,175,000	$251,003,000	$431,689,000
Participating basic earnings	-5,961,000	-2,742,000	0
Basic net income (loss) attributable to common stockholders	532,214,000	248,261,000	431,689,000
Reallocation of participating earnings	16,000	4,000	0
Diluted net income (loss) attributable to common stockholders	532,230,000	248,265,000	431,689,000
Basic	$4.89	$2.39	$4.18
Diluted	$4.88	$2.39	$4.15
Segment, Continuing Operations [Member]
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Income (loss) as reported	538,175,000	238,922,000	408,230,000
Participating basic earnings	-5,961,000	-2,610,000	0
Basic net income (loss) attributable to common stockholders	532,214,000	236,312,000	408,230,000
Reallocation of participating earnings	16,000	4,000	0
Diluted net income (loss) attributable to common stockholders	532,230,000	236,316,000	408,230,000
Basic	$4.89	$2.28	$3.96
Diluted	$4.88	$2.28	$3.93
Segment, Discontinued Operations [Member]
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Income (loss) as reported	0	12,081,000	23,459,000
Participating basic earnings	0	-132,000	0
Basic net income (loss) attributable to common stockholders	0	11,949,000	23,459,000
Reallocation of participating earnings	0	0	0
Diluted net income (loss) attributable to common stockholders	$0	$11,949,000	$23,459,000
Basic	$0	$0.11	$0.22
Diluted	$0	$0.11	$0.22

Net_Income_Per_Share_Reconcili1

Net Income Per Share (Reconciliation Of The Weighted Average Common Shares Outstanding) (Detail)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation Of Basic Weighted Average Common Shares Outstanding To Diluted Weighted Average Common Shares Outstanding [Line Items]
Basic	108,844	103,744	103,190
Diluted	109,132	103,913	103,972
Stock Options [Member]
Reconciliation Of Basic Weighted Average Common Shares Outstanding To Diluted Weighted Average Common Shares Outstanding [Line Items]
Dilutive common shares	83	165	354
Restricted Stock [Member]
Reconciliation Of Basic Weighted Average Common Shares Outstanding To Diluted Weighted Average Common Shares Outstanding [Line Items]
Dilutive common shares	0	0	428
Performance Unit [Member]
Reconciliation Of Basic Weighted Average Common Shares Outstanding To Diluted Weighted Average Common Shares Outstanding [Line Items]
Dilutive common shares	205	4	0

Net_Income_Per_Share_Summary_O

Net Income Per Share (Summary Of The Common Stock Options And Restricted Stock) (Detail)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Restricted Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive common shares	153	9	95
Performance Unit [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive common shares	0	83	0

Other_Current_Liabilities_Sche

Other Current Liabilities (Schedule Of Other Current Liabilities) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Other Liabilities Disclosure [Abstract]
Accrued production costs	$70,786	$48,196
Payroll related matters	34,349	28,498
Accrued interest	69,264	70,000
Asset retirement obligations	9,146	4,481
Other	11,763	5,425
Other current liabilities	$195,308	$156,600

Subsidiary_Guarantors_Condense

Subsidiary Guarantors (Condensed Consolidating Balance Sheet) (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
ASSETS
Accounts receivable - related parties	$0	$0
Other current assets	1,188,396,000	520,875,000
Oil and natural gas properties, net	10,076,878,000	8,831,265,000
Property and equipment, net	129,136,000	114,783,000
Investment in subsidiaries	0	0
Other long-term assets	405,553,000	124,241,000
Total assets	11,799,963,000	9,591,164,000
LIABILITIES AND EQUITY
Accounts payable - related parties	0	0
Other current liabilities	1,427,193,000	756,868,000
Long-term debt	3,517,320,000	3,630,421,000
Other long-term liabilities	1,574,662,000	1,445,926,000
Equity	5,280,788,000	3,757,949,000	3,466,196,000	2,980,739,000
Total liabilities and stockholders' equity	11,799,963,000	9,591,164,000
Parent Company [Member]
ASSETS
Accounts receivable - related parties	6,670,744,000	6,115,554,000
Other current assets	569,545,000	39,108,000
Oil and natural gas properties, net	0	0
Property and equipment, net	0	0
Investment in subsidiaries	4,085,045,000	3,896,741,000
Other long-term assets	330,792,000	74,013,000
Total assets	11,656,126,000	10,125,416,000
LIABILITIES AND EQUITY
Accounts payable - related parties	1,201,950,000	1,261,844,000
Other current liabilities	217,884,000	126,461,000
Long-term debt	3,517,320,000	3,630,421,000
Other long-term liabilities	1,438,184,000	1,348,741,000
Equity	5,280,788,000	3,757,949,000
Total liabilities and stockholders' equity	11,656,126,000	10,125,416,000
Guarantor Subsidiaries [Member]
ASSETS
Accounts receivable - related parties	1,201,950,000	1,261,844,000
Other current assets	618,851,000	481,767,000
Oil and natural gas properties, net	10,076,878,000	8,831,265,000
Property and equipment, net	129,136,000	114,783,000
Investment in subsidiaries	0	0
Other long-term assets	74,761,000	50,228,000
Total assets	12,101,576,000	10,739,887,000
LIABILITIES AND EQUITY
Accounts payable - related parties	6,670,744,000	6,115,554,000
Other current liabilities	1,209,309,000	630,407,000
Long-term debt	0	0
Other long-term liabilities	136,478,000	97,185,000
Equity	4,085,045,000	3,896,741,000
Total liabilities and stockholders' equity	12,101,576,000	10,739,887,000
Consolidation Eliminations [Member]
ASSETS
Accounts receivable - related parties	-7,872,694,000	-7,377,398,000
Other current assets	0	0
Oil and natural gas properties, net	0	0
Property and equipment, net	0	0
Investment in subsidiaries	-4,085,045,000	-3,896,741,000
Other long-term assets	0	0
Total assets	-11,957,739,000	-11,274,139,000
LIABILITIES AND EQUITY
Accounts payable - related parties	-7,872,694,000	-7,377,398,000
Other current liabilities	0	0
Long-term debt	0	0
Other long-term liabilities	0	0
Equity	-4,085,045,000	-3,896,741,000
Total liabilities and stockholders' equity	($11,957,739,000)	($11,274,139,000)

Subsidiary_Guarantors_Condense1

Subsidiary Guarantors (Condensed Consolidating Statement Of Operations) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements Captions [Line Items]
Total operating revenues	$2,660,147,000	$2,319,919,000	$1,819,814,000
Total operating costs and expenses	1,570,402,000	1,702,482,000	969,251,000
Income (loss) from continuing operations	1,089,745,000	617,437,000	850,563,000
Interest expense	-216,661,000	-218,581,000	-182,705,000
Loss on extinguishment of debt	-4,316,000	-28,616,000	0
Other, net	-12,808,000	-13,081,000	-8,587,000
Income from continuing operations before income taxes	855,960,000	357,159,000	659,271,000
Income tax expense	-317,785,000	-118,237,000	-251,041,000
Income from continuing operations	538,175,000	238,922,000	408,230,000
Income from discontinued operations, net of tax		12,081,000	23,459,000
Net income	538,175,000	251,003,000	431,689,000
Parent Company [Member]
Condensed Financial Statements Captions [Line Items]
Total operating revenues	0	0	0
Total operating costs and expenses	-888,632,000	125,924,000	-126,482,000
Income (loss) from continuing operations	888,632,000	-125,924,000	126,482,000
Interest expense	216,661,000	218,581,000	182,705,000
Loss on extinguishment of debt	-4,316,000	-28,616,000
Other, net	188,305,000	749,878,000	753,472,000
Income from continuing operations before income taxes	855,960,000	376,757,000	697,249,000
Income tax expense	-317,785,000	-118,237,000	-251,041,000
Income from continuing operations		258,520,000	446,208,000
Income from discontinued operations, net of tax		-7,517,000	-14,519,000
Net income	538,175,000	251,003,000	431,689,000
Guarantor Subsidiaries [Member]
Condensed Financial Statements Captions [Line Items]
Total operating revenues	2,660,147,000	2,319,919,000	1,812,472,000
Total operating costs and expenses	2,459,034,000	1,576,558,000	1,090,013,000
Income (loss) from continuing operations	201,113,000	743,361,000	722,459,000
Interest expense	0	0	0
Loss on extinguishment of debt	0	0
Other, net	-12,809,000	-13,136,000	-3,148,000
Income from continuing operations before income taxes	188,304,000	730,225,000	719,311,000
Income tax expense	0	0	0
Income from continuing operations		730,225,000	719,311,000
Income from discontinued operations, net of tax		19,598,000	37,978,000
Net income	188,304,000	749,823,000	757,289,000
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements Captions [Line Items]
Total operating revenues			7,342,000
Total operating costs and expenses			5,720,000
Income (loss) from continuing operations			1,622,000
Interest expense			0
Other, net			-6,043,000
Income from continuing operations before income taxes			-4,421,000
Income tax expense			0
Income from continuing operations			-4,421,000
Income from discontinued operations, net of tax			0
Net income			-4,421,000
Consolidation Eliminations [Member]
Condensed Financial Statements Captions [Line Items]
Total operating revenues	0	0	0
Total operating costs and expenses	0	0	0
Income (loss) from continuing operations	0	0	0
Interest expense	0	0	0
Loss on extinguishment of debt	0
Other, net	-188,304,000	-749,823,000	-752,868,000
Income from continuing operations before income taxes	-188,304,000	-749,823,000	-752,868,000
Income tax expense	0	0	0
Income from continuing operations		-749,823,000	-752,868,000
Income from discontinued operations, net of tax		0	0
Net income	($188,304,000)	($749,823,000)	($752,868,000)

Subsidiary_Guarantors_Condense2

Subsidiary Guarantors (Condensed Consolidating Statement Of Cash Flows) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements Captions [Line Items]
Net cash flows provided by (used in) operating activities	$1,673,787,000	$1,362,020,000	$1,237,478,000
Net cash flows used in investing activities	-2,545,996,000	-1,896,794,000	-2,240,444,000
Net cash flows provided by (used in) financing activities	872,209,000	531,915,000	1,005,504,000
Net increase (decrease) in cash and cash equivalents	0	-2,859,000	2,538,000
Cash and cash equivalents at beginning of period	21,000	2,880,000	342,000
Cash and cash equivalents at end of period	21,000	21,000	2,880,000
Parent Company [Member]
Condensed Financial Statements Captions [Line Items]
Net cash flows provided by (used in) operating activities	-888,369,000	-487,131,000	-1,044,006,000
Net cash flows used in investing activities	71,983,000	-32,341,000	23,536,000
Net cash flows provided by (used in) financing activities	816,386,000	519,472,000	1,020,470,000
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0	0	0
Cash and cash equivalents at end of period	0	0	0
Guarantor Subsidiaries [Member]
Condensed Financial Statements Captions [Line Items]
Net cash flows provided by (used in) operating activities	2,562,156,000	1,849,151,000	2,278,647,000
Net cash flows used in investing activities	-2,617,979,000	-1,864,453,000	-1,720,242,000
Net cash flows provided by (used in) financing activities	55,823,000	12,443,000	-555,867,000
Net increase (decrease) in cash and cash equivalents	0	-2,859,000	2,538,000
Cash and cash equivalents at beginning of period	21,000	2,880,000	342,000
Cash and cash equivalents at end of period	21,000	21,000	2,880,000
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements Captions [Line Items]
Net cash flows provided by (used in) operating activities			2,837,000
Net cash flows used in investing activities			-543,738,000
Net cash flows provided by (used in) financing activities			540,901,000
Net increase (decrease) in cash and cash equivalents			0
Cash and cash equivalents at beginning of period			0
Cash and cash equivalents at end of period			0
Consolidation Eliminations [Member]
Condensed Financial Statements Captions [Line Items]
Net cash flows provided by (used in) operating activities	0	0	0
Net cash flows used in investing activities	0	0	0
Net cash flows provided by (used in) financing activities	0	0	0
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	$0	$0	$0

Subsequent_Events_New_Commodit

Subsequent Events (New Commodity Derivative Contracts) (Detail) (Subsequent Event [Member])	3 Months Ended								12 Months Ended
	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2015
	bbl		bbl		bbl		bbl		bbl
Oil Swaps [Member]
Subsequent Event [Line Items]
Volume (Bbl/MMBtu) - Current Year	660,000	[1]	660,000	[1]	660,000	[1]	0	[1]	1,980,000	[1]
Price per Bbl/MMBtu - Current Year	56.6	[1]	56.6	[1]	56.6	[1]	0	[1]	56.6	[1]
Volume (Bbl/MMBtu) - Year One	2,610,000	[1]	180,000	[1]	180,000	[1]	180,000	[1]	3,150,000	[1]
Price per Bbl/MMBtu - Year One	62.48	[1]	61.04	[1]	61.04	[1]	61.04	[1]	62.23	[1]
Oil Basis Swaps [Member]
Subsequent Event [Line Items]
Volume (Bbl/MMBtu) - Year One	368,000	[2]	368,000	[2]	364,000	[2]	364,000	[2]	1,464,000	[2]
Price per Bbl/MMBtu - Year One	-2.48	[2]	-2.48	[2]	-2.48	[2]	-2.48	[2]	-2.48	[2]
[1]	The index prices for the oil price swaps are based on the NYMEX b West Texas Intermediate monthly average futures price.
[2]	The basis differential price is between Midland b WTI and Cushing b WTI.