Concho Resources (CXO) 10-K 25 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 22, 2016
Document Documentand Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Trading Symbol	CXO
Entity Registrant Name	CONCHO RESOURCES INC
Entity Central Index Key	1,358,071
Current Fiscal Year End Date	--12-31
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		129,357,977
Entity Public Float	$ 14,274,370,137

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 228,550,000	$ 21,000
Accounts receivable, net of allowance for doubtful accounts:
Oil and natural gas	203,972,000	250,600,000
Joint operations and other	190,608,000	409,665,000
Derivative instruments	652,498,000	490,351,000
Prepaid costs and other	38,922,000	37,759,000
Total current assets	1,314,550,000	1,188,396,000
Property and equipment:
Oil and natural gas properties, successful efforts method	15,846,307,000	13,867,831,000
Accumulated depletion and depreciation	(5,047,810,000)	(3,790,953,000)
Total oil and natural gas properties, net	10,798,497,000	10,076,878,000
Other property and equipment, net	178,450,000	129,136,000
Total property and equipment, net	10,976,947,000	10,206,014,000
Deferred loan costs, net	15,585,000	20,260,000
Intangible asset - operating rights, net	25,693,000	27,154,000
Inventory	19,118,000	14,435,000
Noncurrent derivative instruments	167,038,000	262,349,000
Other assets	122,945,000	33,172,000
Total assets	12,641,876,000	11,751,780,000
Accounts payable:
Trade	13,200,000	20,380,000
Related parties	0	0
Bank overdrafts	0	92,541,000
Revenue payable	169,787,000	238,098,000
Accrued and prepaid drilling costs	228,523,000	718,300,000
Other current liabilities	184,910,000	195,308,000
Total current liabilities	596,420,000	1,264,627,000
Long-term debt	3,332,188,000	3,469,137,000
Deferred income taxes	1,630,373,000	1,600,751,000
Asset retirement obligations and other long-term liabilities	$ 140,344,000	$ 136,477,000
Commitments and contingencies (Note 10)
Stockholders' equity:
Common stock, $0.001 par value; 300,000,000 authorized; 129,444,042 and 113,264,918 shares issued at December 31, 2015 and 2014, respectively	$ 129,000	$ 113,000
Additional paid-in capital	4,628,390,000	3,027,412,000
Retained earnings	2,345,641,000	2,279,741,000
Treasury stock, at cost; 306,061 and 260,124 shares at December 31, 2015 and 2014, respectively	(31,609,000)	(26,478,000)
Total stockholders' equity	6,942,551,000	5,280,788,000
Total liabilities and stockholders' equity	$ 12,641,876,000	$ 11,751,780,000

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	129,444,042	113,264,918
Treasury shares	306,061	260,124

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating revenues:
Oil sales	$ 1,539,917	$ 2,189,072	$ 1,938,433
Natural gas sales	263,656	471,075	381,486
Total operating revenues	1,803,573	2,660,147	2,319,919
Operating costs and expenses:
Oil and natural gas production	541,359	538,374	455,436
Exploration and abandonments	58,847	284,821	109,549
Depreciation, depletion and amortization	1,223,253	979,740	772,608
Accretion of discount on asset retirement obligations	7,600	7,072	6,047
Impairments of long-lived assets	60,529	447,151	65,375
General and administrative (including non-cash stock-based compensation of $63,073, $47,130 and $35,078 for the years ended December 31, 2015, 2014 and 2013, respectively)	230,734	204,161	169,815
(Gain) loss on derivatives	(699,752)	(890,917)	123,652
Total operating costs and expenses	1,422,570	1,570,402	1,702,482
Income from operations	381,003	1,089,745	617,437
Other income (expense):
Interest expense	(215,384)	(216,661)	(218,581)
Loss on extinguishment of debt	0	(4,316)	(28,616)
Loss on disposition of assets, net	(53,789)	(9,308)	(1,268)
Other, net	(14,559)	(3,500)	(11,813)
Total other expense	(283,732)	(233,785)	(260,278)
Income from continuing operations before income taxes	97,271	855,960	357,159
Income tax expense	(31,371)	(317,785)	(118,237)
Income from continuing operations	65,900	538,175	238,922
Income from discontinued operations, net of tax	0	0	12,081
Net income	$ 65,900	$ 538,175	$ 251,003
Basic earnings per share:
Income from continuing operations	$ 0.54	$ 4.89	$ 2.28
Income from discontinued operations, net of tax	0	0	0.11
Net income	0.54	4.89	2.39
Diluted earnings per share:
Income from continuing operations	0.54	4.88	2.28
Income from discontinued operations, net of tax	0	0	0.11
Net income	$ 0.54	$ 4.88	$ 2.39

Consolidated Statements of Ope5

Consolidated Statements of Operations (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Non-cash stock-based compensation	$ 63,073	$ 47,130	$ 35,078

Consolidated Statement of Stock

Consolidated Statement of Stockholders Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
BALANCE at Dec. 31, 2012	$ 3,466,196	$ 105	$ 1,982,714	$ 1,490,563	$ (7,186)
BALANCE, Shares at Dec. 31, 2012		104,668,000			87,000
Net income	251,003	$ 0	0	251,003	$ 0
Stock options exercised	$ 3,223	$ 0	3,223	0	$ 0
Stock options exercised, shares	174,342	174,000			0
Grants of restricted stock, shares	499
Cancellation of restricted stock, shares		(118,000)			0
Stock-based compensation	$ 35,078	$ 0	35,078	0	$ 0
Excess tax benefits related to stock-based compensation	6,147	0	6,147	0	0
Purchase of treasury stock	(3,698)	$ 0	0	0	$ (3,698)
Purchase of treasury stock, shares		0			40,000
BALANCE at Dec. 31, 2013	3,757,949		2,027,162	1,741,566	$ (10,884)
BALANCE, Shares at Dec. 31, 2013		105,223,000			127,000
Net income	538,175	$ 0	0	538,175	$ 0
Issuance of common stock (Shares)		7,475,000
Issuance of common stock	931,989	$ 7	931,982
Stock options exercised	$ 4,659	$ 1	4,658	0	$ 0
Stock options exercised, shares	207,824	208,000			0
Grants of restricted stock, shares	448
Cancellation of restricted stock, shares		(89,000)			0
Stock-based compensation	$ 47,130	$ 0	47,130	0	$ 0
Excess tax benefits related to stock-based compensation	16,480	0	16,480	0	0
Purchase of treasury stock	(15,594)	$ 0	0	0	$ (15,594)
Purchase of treasury stock, shares		0			133,000
BALANCE at Dec. 31, 2014	5,280,788	$ 113	3,027,412	2,279,741	$ (26,478)
BALANCE, Shares at Dec. 31, 2014		113,265,000			260,000
Net income	65,900	$ 0	0	65,900	$ 0
Issuance of common stock (Shares)		15,755,000
Issuance of common stock	1,535,712	$ 16	1,535,696
Stock options exercised	$ 59	$ 0	59	0	$ 0
Stock options exercised, shares	4,812	5,000			0
Grants of restricted stock, shares	452,436
Cancellation of restricted stock, shares		(33,000)			0
Stock-based compensation	$ 63,073	$ 0	63,073	0	$ 0
Excess tax benefits related to stock-based compensation	2,150	0	2,150	0	0
Purchase of treasury stock	(5,131)	$ 0	0	0	$ (5,131)
Purchase of treasury stock, shares		0			46,000
BALANCE at Dec. 31, 2015	$ 6,942,551	$ 129	$ 4,628,390	$ 2,345,641	$ (31,609)
BALANCE, Shares at Dec. 31, 2015		129,444,000			306,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 65,900	$ 538,175	$ 251,003
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	1,223,253	979,740	772,608
Accretion of discount on asset retirement obligations	7,600	7,072	6,047
Impairments of long-lived assets	60,529	447,151	65,375
Exploration and abandonments, including dry holes	43,737	265,064	80,714
Non-cash stock-based compensation expense	63,073	47,130	35,078
Deferred income taxes	29,622	296,167	102,427
Loss on disposition of assets and other	53,789	9,308	1,268
(Gain) loss on derivatives	(699,752)	(890,917)	123,652
Discontinued operations	0	0	(12,250)
Other non-cash items	14,639	18,379	19,720
Changes in operating assets and liabilities, net of acquisitions and dispositions:
Accounts receivable	117,716	(104,988)	(40,009)
Prepaid costs and other	(3,726)	(23,628)	4,945
Inventory	(5,154)	2,441	509
Accounts payable	(17,689)	1,566	(18,469)
Revenue payable	(68,311)	60,481	28,593
Other current liabilities	12,279	20,646	(59,191)
Net cash provided by operating activities	897,505	1,673,787	1,362,020
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures on oil and natural gas properties	(2,443,704)	(2,554,914)	(1,850,992)
Additions to property, equipment and other assets	(67,699)	(34,320)	(28,678)
Proceeds from the disposition of assets	104	1,305	15,217
Contributions to equity method investments	(91,342)	(30,050)	0
Settlements received from (paid on) derivatives	632,916	71,983	(32,341)
Net cash used in investing activities	(1,969,725)	(2,545,996)	(1,896,794)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of debt	1,490,900	2,081,000	3,257,575
Payments of debt	(1,630,400)	(2,191,500)	(2,729,700)
Exercise of stock options	59	4,659	3,223
Excess tax benefit from stock-based compensation	2,150	16,480	6,147
Net proceeds from issuance of common stock	1,535,712	931,989	0
Payments for loan costs	0	(10,648)	(14,075)
Purchase of treasury stock	(5,131)	(15,594)	(3,698)
Increase (decrease) in bank overdrafts	(92,541)	55,823	12,443
Net cash provided by financing activities	1,300,749	872,209	531,915
Net increase (decrease) in cash and cash equivalents	228,529	0	(2,859)
Cash and cash equivalents at beginning of period	21	21	2,880
Cash and cash equivalents at end of period	228,550	21	21
SUPPLEMENTAL CASH FLOWS:
Cash paid for interest	211,443	211,342	200,961
Cash paid for income taxes	$ 3,950	$ 27,844	$ 21,376

Organization and nature of oper

Organization and nature of operations	12 Months Ended
	Dec. 31, 2015
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 of Southeast New Mexico and West Texas.

Summary of significant accounti

Summary of significant accounting policies	12 Months Ended
	Dec. 31, 2015
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. The Company consolidates the financial statements of these entities. All material intercompany balances and transactions have been eliminated. Retrospective adjustments and reclassifications. Certain reclassifica tions have been made to the 2014 amounts in order to conform to the 2015 presentation and for the retrospective application resulting from the early adoption of Accounting Standards Update (“ASU”) No. 2015-03 and 2015-17 . The retrospective application of ASU 2015-03 resulted in $48.2 million of net deferred loan costs directly related to the Company’s senior notes being reclassified from a non current asset to a direct deduction from the carrying amount of the related senior notes at December 31, 2014. The retrospective application of ASU 2015-17 resulted in the current deferred income tax liability of $162.6 million at December 31, 2014 to be reclassified as a noncurrent deferred income tax liability in the Company’s consolidated balance sheet. Other certain prior period amounts have been reclassified to conform to the 2015 presentation. These reclassifications had no impact on the balance sheet, net income (loss) or cash flows. 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, before income tax expense of approximately $7.5 million. The Co mpany recognized income from discontinued operations, net of tax of $12.1 million for the year ended December 31, 2013 . 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 resul ts could differ from these estimates. Depletion of oi l 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 fut ure recoverable reserves , commodity price outlooks and prevailing market rates of other sources of income and costs . Other significant estimates inclu de, but are not limited to, asset retirement obligations, fair value of derivative financial instruments, fair value of business combinations, fair value of nonmonetary exchanges, 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 inves tments 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, m anagement 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 t he 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 allowance s 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 n ot 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 $ 1.2 million and $ 0.7 million at December 31, 2015 and December 31, 2014 , respectively . Inventory. Inventory consists primarily of tubular goods , water and other oilfield equipment that the Company plans to utilize in its ongoing exploration and develop ment 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 method and straight-line methods. For the interim period ended December 31, 2015 , the Company early adopted ASU No. 2015-03, “Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs,” which requires net deferred loan costs directly related to the Company’s senior notes to be classified as a direct deduction from the carryin g amount of the related senior notes. The Company retrospectively adopted the ASU and reclassified $ 48.2 million at December 31, 2014 from a non current asset to a deduction from long-term debt. The deferred loan costs related to the Co mpany’s credit facility remain classified as a non current asset due to the revolving nature of that facility. The provisions of the ASU were adopted primarily to simplify the required reporting for subsequent registration filings. The Company had deferred loan costs related to its senior notes of $ 42.9 million and $ 48.2 million, net of accumulated amortization of $ 18.7 million and $ 13.4 million, as a reduction of long-term debt at Decemb er 31, 2015 an d December 31, 2014 , respectively. The Company had deferred loan costs related to the credit facility of $ 15.6 million and $ 20.3 million, net of accumulated amortization of $ 51.0 millio n and $ 46.3 million, in non current assets at December 31, 2015 and December 31, 2014 , 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 and integ rated assets is based on the unit-of-production method using proved dev eloped reserves . During the years ended December 31, 2015 , 2014 and 2013 , the Company recognized depletion expense from continuing operations of $ 1,203.5 million, $ 960.9 million and $ 756.0 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 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 pro ject. 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 c ommercial viability. In these instances, the project ’ s feasibility is not contingent upon price improvements or advances in technology, but rather the C ompany’ s ongoing efforts and expenditures related to accurately predicting the hydrocarbon recoverabilit y based on well information, ga ining 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 consta ntly. 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 additio nal in formation 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 depletio n. 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 d epletion 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 unti l such projects ar e ready for their intended use. During the y ears ended December 31, 2015 and 2014 , the Company had capitalized interest of $ 0.7 million and $ 1.4 million, respectively. The Company did not capitalize interest during 2013 . 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 i s 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 val ue 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 b ase. 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 and integrated assets would be recognized at that time. Estimating future cash flows involves the use of judgments, includ ing 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 and cash flows from integrated assets . The Com pan y recognized impairment expense of $ 60.5 million, $ 447.2 million , and $ 65.4 million during the years ended December 31, 2015 , 2014 and 2013 , respectively, related to its proved oil and natura l gas properties. 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, 2015 , 2014 and 2013 , the Company recognized expense of $ 34.5 million, $ 217.3 million and $ 49.8 million, respectively, related to abandoned pro spects 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 equ ipment 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 $ 178.5 million and $ 129.1 million, net of accumulated depreciation of $ 54.4 million and $ 52.5 millio n, at December 31, 2015 and December 31, 2014 , respectively. During the years ended December 31, 2015 , 2014 and 2013 , the Company recognized depreciation expense of $ 18.3 million, $ 17.3 million and $ 15.2 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, 2015 and 2014 , respectively : December 31, (in thousands) 2015 2014 Gross intangible - operating rights $ 36,557 $ 36,557 Accumulated amortization (10,864) (9,403) Net intangible - operating rights $ 25,693 $ 27,154 The following table reflects amortization expense from continuing operations for the years ended December 31, 2015 , 2014 and 2013 : Years Ending December 31, (in thousands) 2015 2014 2013 Amortization expense $ 1,461 $ 1,461 $ 1,461 The following table reflects the estimated aggregate amortization expense for each of the periods presented below at December 31, 2015 : (in thousands) 2016 $ 1,461 2017 1,461 2018 1,461 2019 1,461 2020 1,461 Thereafter 18,388 Total $ 25,693 Equity method investment s . 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 has the option to purchase the member interest of the other investor in ACC. This purchase option becomes exercisable three months after the completion date of the pipeline and remains exercisable for a period of twelve months. The Company accounts for its investm ent in ACC under the equity method of accounting for investments in unconsolidated affiliates. The Co mpany’s net investment in ACC was approximately $ 98.9 million and $ 29.5 million at December 31, 2015 and December 31, 2014 , respectively, and was included in other assets in the Company’s consolidated balance sheet. The equity loss for the years ended December 31, 2015 and 2014 was approximately $ 4.1 million and $ 1.3 million , respectively, and wa s included in other expense in the Company’s consolidated statement of operations. During 2015 and 2014 , the Company recorded approximately $ 2.9 million and $ 0.7 million, respectively, of capitalized interest on its investment in ACC. ACC started partial operations in late 2015. The Company expects the system to be fully operational during 2016. During 2015, the Company purchased a 25 percent member interest in an entity, which is constructing a crude oil gathering a nd transportation system in the southern Delaware Basin. The system is expected to be completed and operational during 2016. The Company accounts for its investment under the equity method of accounting for investments in unconsolidated affiliates . The Com pany’s net investment is approximately $ 20.8 million at December 31, 2015 and is included in other assets in the Company’s consolidated balance sheet. 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 paymen ts is fixed and readily determinable. At December 31, 2015 and 2014 , the Company has accrued approximately $ 1.0 million and $ 1.7 million, respectively, related to environmental liabilities. During the years ended December 31, 2015 , 2014 and 2013 , the Company recognized environmental charges of approximately $ 2.7 million, $ 4.0 million and $ 3.4 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, 2015 , 2014 or 2013 . The Company may also enter into physical d elivery 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 Compa ny’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 rel ated 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 incre ase in the carrying amount of the liability and as corresponding accretion expense. Based on certain factors including commodity prices and costs, the Company may revise its previous estimates related to the liability, which would also increase or decrease the associated oil and gas property asset. Treasury stock. Treasury stock purchases are recorded at cost. 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 imbala nces. Oil and n atural 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. I mbalances 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 Com pany 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 re corded 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, 2015 or 2014 . General and administrative expense . The Company receiv es fe es for the operation of jointly- owned oil and natural gas properties and records such reimbursements as reductions of general and administrative expense. Such fees totaled approximately $ 24.3 million, $ 23.2 million and $ 18.5 million for the years e nded December 31, 2015 , 2014 and 2013 , respectively. Stock-based compensation. For stock-based compensation awards granted, stock-based compensation expense is being recognized in the Company’ s financial statements on a n 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 price s for the fair value of restricted stock and (iii) the Monte Carlo simulation method for the fair value of performance unit awards. Income taxes. In November 2015, the FASB issued ASU No. 2015-17, “Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes,” which requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. The Company early adopted the ASU retrospectively for the interim period ended December 31, 2015, which resulted in its current deferred income tax liability of $162.6 million at December 31, 2014 to be reclassified as a noncurrent deferred income tax liability in the Company’s consolidated balance sheet. The provisions of the ASU were adopted primarily to simplify the required reporting for subsequent registration filings. The Company previously classified deferred incom e tax liabilities and assets separately to current and noncurrent. 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 effe ct 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 cons olidated financial statements. To recognize a tax position, the Company determines whether it is more likely than not that the tax posi tions will be sustained upon examination, including resolution of any related appeals or litigation, based on the te chnical 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 consol idated 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 b eing realized upon settlement. The Comp any had no material uncertain tax positions that required recognition in the consolidated financial statements at December 31, 2015 and 2014 . Any interest or penalties would be recognized as a component of income tax expense. Recent accounting prono uncements. In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” which outlines a new, single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersede s 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. In August 2015, the FASB issued ASU No. 2015-14, “Revenue from Contracts with Custo mers (Topic 606): Deferral of the Effective Date,” which deferred the effective date of ASU 2014-09 by one year. That new standard is now effective for annual reporting periods beginning after December 15, 2017. 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 fi nancial statements. The Company is evaluating the impact that this new guidance will have on its consolidated financial statements.

Exploratory well costs

Exploratory well costs	12 Months Ended
	Dec. 31, 2015
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 expe nse 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, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Beginning capitalized exploratory well costs $ 241,657 $ 144,504 $ 118,806 Additions to exploratory well costs pending the determination of proved reserves 102,846 234,057 130,967 Reclassifications due to determination of proved reserves (227,746) (99,657) (94,114) Exploratory well costs charged to expense (559) (37,247) (11,155) Ending capitalized exploratory well costs $ 116,198 $ 241,657 $ 144,504 The following table provides an aging at December 31, 2015 and 2014 of capitalized exploratory well costs based on the date drilling was completed: December 31, (dollars in thousands) 2015 2014 Capitalized exploratory well costs that have been capitalized for a period of one year or less $ 98,764 $ 232,346 Capitalized exploratory well costs that have been capitalized for a period greater than one year 17,434 9,311 Total capitalized exploratory well costs $ 116,198 $ 241,657 Number of projects with exploratory well costs that have been capitalized for a period greater than one year 8 7 Delaware Basin project s . At December 31, 2015 , the Company had approximately $ 7.2 million of suspended well costs grea ter than one year recorded for two well s that were initially drille d to monitor nearby wells and are additionall y being used to determine the productivity potential of additional zones . At December 31, 2015 , the Company also had approximately $ 5.7 million of suspended well costs grea ter than one year recorded for a well spud in late 2014 that is te sting multiple zones and is expected to be completed in the first half of 2016. All three wells completed drilling in 2014. Projects operated by others. At December 31, 2015 , the Company had approximately $ 4.5 million of suspended well cos ts greater than one year recorded for five wells that are operated by others and waiting on completion.

Acquisitions and business combi

Acquisitions and business combinations	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Acquisitions and business combinations	Note 4 . Acquisition and divestiture Clayton Williams Acreage Exchange . In December 2015 , the Company completed a nonmonetary acreage exchange with Clayton Williams Energy, Inc. that consolidated acres into a concentrated, operated position in the southern Delaware Basin. The Company recognized a loss on disposition of assets of approximately $50.0 million related to the acreage exchange based on the fair value of the assets surrendered, which is presented in loss on disposition of assets, n et, in the consolidated statement of operations for the year ended December 31, 2015.

Asset retirement obligations

Asset retirement obligations	12 Months Ended
	Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset retirement obligations	Note 5 . 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 repre sent a component of the Company’ s credit-adjusted risk-free rate that is utilized in the calculations o f ass et retirement obligations. The Company’s asset retirement obligation transactions during the years ended December 31, 2015 , 2014 and 2013 are summarized in the table below: Years Ended December 31, (in thousands) 2015 2014 2013 Asset retirement obligations, beginning of period $ 119,881 $ 101,593 $ 86,261 Liabilities incurred from new wells 4,052 5,324 6,338 Liabilities assumed in acquisitions 2,434 4,065 593 Accretion expense 7,600 7,072 6,047 Liabilities settled upon plugging and abandoning wells (2,736) (2,926) (3,447) Revision of estimates (a) (11,286) 4,753 5,801 Asset retirement obligations, end of period $ 119,945 $ 119,881 $ 101,593 (a) The downward revision to the Company’s asset retirement obligation estimates for the year ended December 31, 2015 is primarily due to a reduction in the future estimated abandonment costs.

Incentive plans

Incentive plans	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Incentive plans	Note 6 . 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, 2015 , 2014 and 2013 , 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, 2015 , 2014 and 2013 were approximately $ 9.5 million , $ 8.1 m illion and $ 6.6 million, respectively, of which a portion was recoverable from other working interest owners. Stock incentive plan. The Company’s 2015 Stock Incentiv e Plan (the “Plan”) provides for granting stock options, restricted stock awards and performance awards to directors, officers and employees of the Company. A total of 10.5 million shares of common stock have been authorized for issuance under the Plan. At December 31, 2015 , the Company had 2.9 million shares of common stock 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 year ended D ecember 31, 2015 is presented below: Weighted Average Number of Grant Date Restricted Fair Value Shares Per Share Restricted stock: Outstanding at December 31, 2014 1,091,309 $ 106.33 Shares granted 452,436 $ 109.76 Shares cancelled / forfeited (33,124) $ 111.08 Lapse of restrictions (310,974) $ 96.15 Outstanding at December 31, 2015 1,199,647 $ 110.14 For restricted stock awards granted, stock-based compensation expense is being recognized in the Company’ s financial statements on a n 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 price s 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, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Fair value for awards granted during the period (a) $ 49,659 $ 57,940 $ 44,947 Fair value for awards vested during the period $ 35,700 $ 59,226 $ 21,496 Stock-based compensation expense from restricted stock $ 43,185 $ 36,585 $ 30,984 Income tax benefit related to restricted stock $ 16,049 $ 13,672 $ 11,650 (a) The weighted average grant date fair value per share amounts were $109.76, $129.12 and $88.19 for the years ended December 31, 2015, 2014 and 2013, respectively. 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 t he Company’s stock option award activity under the Plan for the years ended December 31, 2015 , 2014 and 2013 is presented below: Years Ended December 31, 2015 2014 2013 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 47,713 $ 17.49 255,537 $ 21.50 429,879 $ 20.28 Options exercised (4,812) $ 12.00 (207,824) $ 22.42 (174,342) $ 18.48 Outstanding at end of period 42,901 $ 18.10 47,713 $ 17.49 255,537 $ 21.50 Vested and exercisable at end of period 42,901 $ 18.10 47,713 $ 17.49 255,537 $ 21.50 The intrinsic value of options exercised during 2015 , 2014 and 2013 was approximately $ 0.4 million, $ 23.2 million and $ 13.2 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, 2015 : December 31, 2015 Weighted Intrinsic Average Weighted Value Range of Remaining Average of Exercise Number Contractual Exercise Options Prices Vested Life Price (in thousands) Vested and exercisable options: $12.00 - $12.85 15,824 1.54 years $ 12.81 1,267 $20.40 - $22.77 27,077 2.98 years $ 21.20 1,940 42,901 2.45 years $ 18.10 $ 3,207 The following table shows the deductions in current taxable income related to stock options exercised for the years ended December 31, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Deductions in current taxable income related to stock options exercised $ 415 $ 23,208 $ 13,193 Performance unit awards. During the years ended December 31, 2015 , 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 es timated 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, 2015 , 2014 and 2013 : Years Ended December 31, 2015 2014 2013 Risk-free interest rate 1.07% 0.76% 0.37% Range of volatilities 26.1% - 43.0% 29.2% - 42.2% 31.5% - 45.1% The following table summarizes the performance unit activity for the year ended December 31, 2015 : Number of Grant Date Units Fair Value Performance units: Outstanding at December 31, 2014 250,314 $ 127.07 Units granted (a) 176,330 $ 156.86 Units vested (b) (110,889) $ 111.40 Outstanding at December 31, 2015 315,755 $ 149.21 (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. (b) On December 31, 2015, the performance period ended for these performance units. Each unit converted into 1.625 shares representing 180,199 shares of common stock issued on January 4, 2016. The following table summarizes information about stock-based compensation expense for performance units for the years ended December 31, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Fair value for awards granted during the period $ 27,659 $ 19,455 $ 12,352 Stock-based compensation expense from performance units $ 19,888 $ 10,545 $ 4,080 Income tax benefit related to performance units $ 7,391 $ 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 s tock-bas ed compensation awards that we re outstanding at December 31, 2015 : Restricted Performance (in thousands) Stock Units Total 2016 $ 31,992 $ 15,734 $ 47,726 2017 18,189 9,219 27,408 2018 6,466 - 6,466 2019 286 - 286 2020 4 - 4 Total $ 56,937 $ 24,953 $ 81,890

Disclosures about fair value of

Disclosures about fair value of financial instruments	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Disclosures about fair value of financial instruments	Note 7 . Disclosures about fair value measurements 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. Th e 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 input s 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 ar e 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-e xchange 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 con sider various inputs including: ( i ) quoted forward prices for commodities, (ii) time value, (iii) volatility factors and (iv) current market and contractual prices for the un derlying 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, 2015 and 2014 : December 31, 2015 December 31, 2014 Carrying Fair Carrying Fair (in thousands) Value Value Value Value Assets: Derivative instruments $ 819,536 $ 819,536 $ 752,700 $ 752,700 Liabilities: Credit facility $ - $ - $ 139,500 $ 131,068 $600 million 7.0% senior notes due 2021 (a) $ 592,414 $ 595,500 $ 591,213 $ 625,500 $600 million 6.5% senior notes due 2022 (a) $ 591,549 $ 579,000 $ 590,454 $ 628,500 $600 million 5.5% senior notes due 2022 (a) $ 592,899 $ 553,500 $ 592,061 $ 598,500 $1,550 million 5.5% senior notes due 2023 (a) $ 1,555,326 $ 1,453,005 $ 1,555,909 $ 1,573,875 (a) The carrying value includes associated deferred loan costs and any (discount) premium. See Note 2 for additional information regarding the Company’s retrospective adoption of ASU No. 2015-03. 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. Seni or 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 th e 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, 2015 and 2014 . The Company nets the fair value of derivative instruments by counterparty in the Company’s consolidated balance sheets. December 31, 2015 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 $ - $ 684,029 $ - $ 684,029 $ (31,531) $ 652,498 Noncurrent: Commodity derivatives - 175,267 - 175,267 (8,229) 167,038 Liabilities Current: Commodity derivatives - (31,531) - (31,531) 31,531 - Noncurrent: Commodity derivatives - (8,229) - (8,229) 8,229 - Net derivative instruments $ - $ 819,536 $ - $ 819,536 $ - $ 819,536 December 31, 2014 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 Concentrations of credit risk. At December 31, 2015 , the Company ’ s primary concentration of credit risks are the risk of collec ting accounts receivable and the risk of counterparties ’ failure to perform under de rivative obligations. See Note 12 for in formation 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 te rms of the ISDA Agreements provide the Company and the co unterparties 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 8 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 periodically review s their long-lived assets to be held and used, including proved oil and natural gas properties and their integrated assets , whenever events or circumstances indi cate that the carrying value of those assets may not be recoverable, for instance when there are declines in commodity prices or well performance. The Company review s its oil and natural gas properties by depletion base or by individual well for those well s not constituting part of a depletion base. 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. If the estimated undiscounted future net cash flows are less than the carrying amount of the Company’s assets, it 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 calculate s the expected undiscounted future net cash flows of it s long-lived assets and its integrated assets using management’s assumptions and expectations of ( i ) commodity prices, which are based on the New York Mercantile Exchange (“ NYMEX ”) strip, (ii) pricing adjustments for differentials, (iii) production costs, (iv) capital expenditures, (v) production volumes, (vi) proved reserves and risk-adjusted probable and possible reserves, and (vii) other sources of income and expenses from integrated assets. The Company calculate s the estimated fair values of its long-l ived assets and their integrated assets using a discounted future cash flow model. Fair value assumptions associated with the calculation of discounted future net cash flows include ( i ) market estimates of commodity prices, (ii) pricing adjustments for dif ferentials, (iii) production costs, (iv) capital expenditures, (v) production volumes, (vi) estimated proved reserves and risk-adjusted probable and possible reserves, (vii) prevailing market rates of income and expenses from integrated assets and (viii) d iscount rate. The Company discount s the future net cash flows using a market-based weighted average cost of capital rate determined appropriate at the time. These are classified as Level 3 fair value assumptions. As a result of the carrying amount of cert ain of the Company’s long-lived assets being less than their expected undiscounted future net cash flows, the Company recognized a non-cash charge aga inst earnings for the amount by which the carrying amount exceeded the estimated fair value of the 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 December 2015 $ 104,982 $ 52,041 $ 52,941 September 2015 $ 18,023 $ 10,435 $ 7,588 December 2014 $ 677,021 $ 245,346 $ 431,675 September 2014 $ 26,790 $ 11,314 $ 15,476 June 2013 $ 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 impair carrying values. The primary factors that may affect estimates of future net cash flows are ( i ) commodity 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, (iv) results of future d rilling activities and (v) changes in income and expenses from integrated assets. Based on the factors above as of December 31, 2015 , the Company determined that undiscounted future cash flows attributable to c ertain depletion group s indicated that the carrying amount s were expec ted to be recovered; however, they may be at risk for impairment if management’s estimates of future cash flows further decline.

Derivative financial instrument

Derivative financial instruments	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative financial instruments	Note 8 . 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 instrument s for speculative or trading purposes. The Company may also enter into physical delivery contracts to effectively provide commodity price hedges. Because these physical delivery contracts are not expected to be net cash settled, they are considered to be n ormal 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 statem ents of operations as they occur. The followin g table summarizes the gains ( losses ) reported in earnings related to the commodity derivative instruments for the years ended December 31, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Gain (loss) on derivatives: Oil derivatives $ 675,303 $ 869,421 $ (133,890) Natural gas derivatives 24,449 21,496 10,238 Total $ 699,752 $ 890,917 $ (123,652) The following table represents the Company’s cash receipts from (payments on) derivatives for the years ended December 31, 2015, 2014 and 2013: Years Ended December 31, (in thousands) 2015 2014 2013 Cash receipts from (payments on) derivatives: Oil derivatives $ 597,297 $ 76,335 $ (41,616) Natural gas derivatives 35,619 (4,352) 9,275 Total $ 632,916 $ 71,983 $ (32,341) Commodity derivative contracts at December 31, 2015 . The following table sets forth the Company’s outstanding derivative contracts at December 31, 2015 . When aggregating multiple contracts, the weighted average contract price is disclosed. All of the Company’s derivative contracts at December 31, 2015 are expected to settle by Dec ember 31, 2017. First Second Third Fourth Quarter Quarter Quarter Quarter Total Oil Swaps: (a) 2016: Volume (Bbl) 6,722,000 5,985,000 5,460,000 5,054,000 23,221,000 Price per Bbl $ 71.99 $ 73.38 $ 74.21 $ 59.38 $ 70.13 2017: Volume (Bbl) 4,354,000 4,118,000 2,655,000 2,655,000 13,782,000 Price per Bbl $ 61.59 $ 62.03 $ 55.23 $ 55.23 $ 59.27 Oil Basis Swaps: (b) 2016: Volume (Bbl) 6,035,000 5,732,000 5,520,000 5,060,000 22,347,000 Price per Bbl $ (1.49) $ (1.50) $ (1.46) $ (1.48) $ (1.48) 2017: Volume (Bbl) 3,780,000 3,822,000 1,012,000 1,012,000 9,626,000 Price per Bbl $ (1.32) $ (1.32) $ (0.54) $ (0.54) $ (1.16) Natural Gas Swaps: (c) 2016: Volume (MMBtu) 7,280,000 7,280,000 7,360,000 7,360,000 29,280,000 Price per MMBtu $ 3.02 $ 3.02 $ 3.02 $ 3.02 $ 3.02 (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. Derivative counterparties. The Company uses credit and other financial criteria to evaluate the creditworthiness of counterparties to its derivative instruments. The Company believes that all of its derivative counterparties are currently acceptable credit risks. Other than provided by the Company’s revolving credit facility, the Company is not required to provide credit support or collateral to any counterparties under its derivative contracts, nor are they required to provide credit support to the Company. See additional information in Note 12 .

Debt

Debt	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt	Note 9 . Debt The Company’s debt consisted of the following at December 31, 2015 and 2014 : December 31, (in thousands) 2015 2014 Credit facility $ - $ 139,500 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 25,073 27,820 Deferred loan costs, net (42,885) (48,183) Less: current portion - - Total long-term debt $ 3,332,188 $ 3,469,137 Credit facility. The Company’s credit facility, as amended and restated (the “Credit Facility”), has a maturity date of May 9 , 2019 . In April 2015, the Company amended its credit agreement to remove the current ratio financial covenant. The Company’s borrowing base is $3. 25 billion until the next scheduled borrowing base redetermination in May 2016. A t December 31, 2015 , commitments from the Company’s bank group total ed $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 Cha se Bank (“JPM Prime Rate”) (3.50 percent at D ecember 31, 2015 ) or (ii) a Eurodollar rate (substantially equal to the LIBOR ). At December 31, 2015 , the interest rates of Eurodollar rate advances and JPM Prime Rate advances varied, with i nterest margins ranging from 125 to 225 basis points and 25 to 1 25 basis points per annum, respectively, depending on the balance outstanding on the Credit Facility . During the years ended December 31, 2015 , 2014 and 2013 , the Company incurred commitment fees on the unused portion of the available commit ments of $ 7.0 million, $ 7.7 million and $ 8.3 million, respectively. Under the current Credit Facility, commitment fees range from 3 0 to 37.5 basis points per annum. The Company had approximately $ 2.5 b illion of unused commitments under its credit facility at December 31, 2015 . The Company’s obligations under t he Credit Facility are secured by a first lien on substantially all of its oil and natural gas properties. At December 31, 2015 , 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 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 ex penses to be no greater than 4. 25 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 th e 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 outstandin g 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, 2015 , the C ompany was in compliance with the covenants under all of its debt instruments . Principal maturities of long-term debt. Principal maturities of long -term debt outstanding at December 31, 2015 were as follows: (in thousands) 2016 $ - 2017 - 2018 - 2019 - 2020 - Thereafter 3,350,000 Total $ 3,350,000 Interest expense. The following amounts have been incurred and charged to interest expense for the years ended December 31, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Cash payments for interest $ 211,443 $ 211,342 $ 200,961 Amortization of original issue discount (premium) (2,747) (2,599) (1,248) Amortization of deferred loan origination costs 9,971 10,937 13,172 Accretion expense 1,795 - - Net changes in accruals (165) (737) 5,696 Interest costs incurred 220,297 218,943 218,581 Less: capitalized interest (4,913) (2,282) - Total interest expense $ 215,384 $ 216,661 $ 218,581

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	Note 10 . Commitments and contingencies Severance agreements. The Company has entered into severance and change in control agreem ents with all of its officers. The current annual salaries for the Company’s officers covered under such agr eements total approximately $ 8.5 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 clai ms 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 n ot 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 re gular 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 in terest 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 interpretatio n s 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, 2015 and 2014 , the Company h ad $ 13.4 million and $ 12.3 million, respectively , accrued for estimated exposure. Although the Company believe s that it has estimated its exposure with respect to the various laws and regulations, administrative rulings and interpretations thereof, adjustments could be required as new interpretations and regulations are is sued. C ommitments. The Company periodically enters into contractual arrangements under which the Company is committed to expend funds. These contractual arrangements relate to purchase agreements the Company has entered into including daywork drilling contracts, water commitment agreements, throug hput volume delivery commitments, power commitments and maintenance commitments . The following table summarizes the Company’s commitments at December 31, 2015 : (in thousands) 2016 $ 51,710 2017 21,256 2018 21,148 2019 13,196 2020 7,335 Thereafter 45,451 Total $ 160,096 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, 2015 , 2014 and 2013 were approximately $ 8.0 million , $ 7.2 million and $ 5.7 million, respectively . Future minimu m lease commitments under non-cancellable operating leases at December 31, 2015 were as follows: (in thousands) 2016 $ 7,941 2017 7,877 2018 7,087 2019 5,651 2020 4,738 Thereafter 5,091 Total $ 38,385

Income taxes

Income taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income taxes	Note 11 . 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 f ile 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, 2015 the Company had current income taxes rec eivable of approximately $ 37.3 million and current income taxes payable of approximately $ 1.0 million . 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. The Company continually assesses both posi tive 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 th e 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, 2015 and 2014 , the Company had no valuation allowances related to its deferred tax assets. At December 31, 2015 , the Company did not have any significant uncertain tax positions requiring recognition in the financial statements. The tax years 2012 through 2015 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, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Income from continuing operations $ 31,371 $ 317,785 $ 118,237 Income from discontinued operations - - 7,518 Changes in stockholders’ equity: Excess tax benefits related to stock-based compensation (2,150) (16,480) (6,147) $ 29,221 $ 301,305 $ 119,608 The Company’s income tax provision attributable to income from continuing operations consisted of the following for the years ended December 31, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Current: U.S. federal $ 127 $ 16,621 $ 12,504 U.S. state and local 1,622 4,997 3,306 Total current income tax provision 1,749 21,618 15,810 Deferred: U.S. federal 40,364 278,615 119,985 U.S. state and local (10,742) 17,552 (17,558) Total deferred income tax provision 29,622 296,167 102,427 Total income tax provision attributable to income from continuing operations $ 31,371 $ 317,785 $ 118,237 The reconciliation between the income tax expense computed by multiplying pre- tax 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) 2015 2014 2013 Income at U.S. federal statutory rate $ 34,045 $ 299,586 $ 125,006 State income taxes (net of federal tax effect) 3,071 22,826 12,505 Revisions of previous estimates (631) 738 1,400 Change in estimated effective statutory state income tax (9,026) (7,945) (21,876) Nondeductible expense & other 3,912 2,580 1,202 Income tax expense $ 31,371 $ 317,785 $ 118,237 Effective tax rate 32.3% 37.1% 33.1% The Company monitors changes in enacted tax rates for the jurisdictions in which it operates. The Company monitors its state tax apportionment footprint and makes updates for changes in its projected activity, including changes in budgets and drilling plans. During 2013, the state of New Mexico passed legislation to phase in a tax rate reduction over the next five years. In June of 2015, the State of Texas enacted legislation to reduce its rate. 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 $9.0 million, $7.9 million and $21.9 million during 2015, 2014 and 2013, respectively. The Company’s effective tax rate decreased in 2015 as compared to 2014. The primary reason for the decrease is lower income, which caused a mor e pronounced impact for each reconciling item, as compared with 2014. In particular, the reduction in our blended state rate caused a 9.3% reduction, partially offset by other reconciling and non-deductible items for a net rate reduction of 4.8% over 2014. The Company’s income tax provision attributable to income from discontinued operations consisted of the following for the year ended December 31, 2013 : Year Ended (in thousands) December 31, 2013 Current: U.S. federal $ 144 U.S. state and local 25 Total current income tax provision 169 Deferred: U.S. federal 6,397 U.S. state and local 952 Total deferred income tax provision 7,349 Total income tax provision attributable to income from discontinued operations $ 7,518 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) 2015 2014 Deferred tax assets: Stock-based compensation $ 36,738 $ 24,810 Asset retirement obligation 44,573 44,802 Other 29,574 28,925 Total deferred tax assets 110,885 98,537 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 (1,420,275) (1,401,313) Intangible assets - operating rights (9,548) (10,148) Derivative instruments (304,550) (281,303) Other (6,885) (6,524) Total deferred tax liability (1,741,258) (1,699,288) Net deferred tax liability $ (1,630,373) $ (1,600,751)

Major customers and derivative

Major customers and derivative counterparties	12 Months Ended
	Dec. 31, 2015
Major Customer Disclosure [Abstract]
Major Customers and Derivative Counterparties [Text Block]	Note 12 . 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 during the years ended December 31, 2015 , 2014 and 2013 : Years Ended December 31, 2015 2014 2013 Holly Frontier Refining and Marketing, LLC 25% 17% 30% Enterprise Crude Oil LLC 12% 12% 13% Plains Marketing and Transportation, Inc. 11% 6% 4% Western Refining Company LP 5% 12% 1% At December 31, 2015 , the Company had receivables from Holly Frontier Refining and Marketing , LLC, Enterprise Crude Oil LLC, Plains Marketing & Transportation Inc. and Western Refining Company LP of $ 31.7 million, $ 10.4 million $ 11.6 million and $ 3.9 million, respectively, which are reflected in a ccounts receivable — oil and natural gas in the accompanying consolidated balance sheets. Derivative counterparties. The Company uses credit and other financial criteria to evaluate the creditworthiness of counterparties to its derivative instruments. The Company’s Credit Facility require s 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. r ating system or (ii) a lender or related affiliate under the Company’s Credit F acility. At December 31, 2015 and 2014 , the counterparties with whom the Company had outstand ing derivative contracts met or exceeded the se 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 r isk policies and procedures and by the criteria of the Company’s Credit F acility . At December 31, 2015 , the Company had a net asset position of $ 819.5 million as a result of outstanding derivative contracts which are reflected in the accompany ing consolidated balance sheets. The Company assessed this balance for concentration risk and noted balances of approximately $ 121.8 million, $ 100.5 million, $ 90.3 million and $ 74.7 million with Bar clays Bank PLC, J.P. Morgan Chase Bank, Wells Fargo Bank, N.A. and KeyBank National Association, respectively.

Related party transactions

Related party transactions	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Related party transactions	Note 13 . Related party transactions The following table summarize s charges incurred with and payments made to related parties and reported in the Company’s consol idated statements of operations for the periods presented: Years Ended December 31, (in thousands) 2015 2014 2013 Amounts paid to a partnership in which a director has an ownership interest (a) $ 5,745 $ 15,181 $ 7,255 Amounts paid to a director and certain officers of the Company (b) $ 593 $ 383 $ 43 Amounts paid under consulting agreement with Steven L. Beal (c) $ - $ - $ 865 Amounts received from a director and certain officers of the Company (d) $ 237 $ 169 $ 84 (a) 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. (b) Amounts include revenue interests, overriding royalty interests and net profits interests in properties owned by the Company made to a director and certain officers (or affiliated entities). Amounts also include payments for an acreage acquisition and lease bonuses to an affiliated entity of an office r. (c) 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. Be al 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. (d) Amounts include p ayments to the Company as a result of activity on oil and natural gas properties in which a director and certain officers (or affiliated entities) have an interest. 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.

Net income per share

Net income per share	12 Months Ended
	Dec. 31, 2015
Earnings Per Share, Basic and Diluted, Other Disclosures [Abstract]
Net income per share	Note 14 . Net income per share T he 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 calcul ations 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 discontinu ed operations and net income attributable to common stockholders to the basic and diluted earnings used to determine the Company’s income per shar e amounts for t he years ended December 31, 2015 , 2014 and 2013 , respectively, under the two-class me thod : Years Ended December 31, (in thousands, except per share amounts) 2015 2014 Income as reported $ 65,900 $ 538,175 Participating basic earnings (635) (5,961) Basic income attributable to common stockholders 65,265 532,214 Reallocation of participating earnings 2 16 Diluted income attributable to common stockholders $ 65,267 $ 532,230 Income per common share: Basic $ 0.54 $ 4.89 Diluted $ 0.54 $ 4.88 Year Ended December 31, 2013 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 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, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Weighted average common shares outstanding: Basic 119,926 108,844 103,744 Dilutive common stock options 25 83 165 Dilutive performance units 422 205 4 Diluted 120,373 109,132 103,913 The following table is a summary of the 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) 2015 2014 2013 Number of antidilutive common shares: Antidilutive performance units - - 83

Other current liabilities

Other current liabilities	12 Months Ended
	Dec. 31, 2015
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, 2015 and 2014 : December 31, (in thousands) 2015 2014 Other current liabilities: Accrued production costs $ 70,876 $ 70,786 Payroll related matters 29,411 34,349 Accrued interest 68,925 69,264 Asset retirement obligations 8,626 9,146 Other 7,072 11,763 Other current liabilities $ 184,910 $ 195,308

Subsidiary guarantors

Subsidiary guarantors	12 Months Ended
	Dec. 31, 2015
Guarantees [Abstract]
Subsidiary guarantors	Note 16 . Subsidiary guarantors All of the Company’s 100 percent owned 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 no t 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 dissoluti on 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 writte n 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 9 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 subsidi aries as subsidiary guarantors. The following condensed consolidating balance s heets at December 31, 2015 and 2014 , condensed c o nsolidating sta tements of o perations and condensed consolidating statements of cash flows for the years ended December 31, 2015 , 2014 and 2013 , present financial information fo r Concho Resources Inc. as the p arent on a stand-alone basis (carrying any investment s in subsidiaries under the equity method), financial information for the subsidiary guarantors 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 are not restricted from making distributions to the Company. Condensed Consolidating Balance Sheet December 31, 2015 Parent Subsidiary Consolidating (in thousands) Issuer Guarantors Entries Total ASSETS Accounts receivable - related parties $ 8,502,099 $ 1,162,297 $ (9,664,396) $ - Other current assets 753,716 560,834 - 1,314,550 Oil and natural gas properties, net - 10,798,497 - 10,798,497 Property and equipment, net - 178,450 - 178,450 Investment in subsidiaries 3,698,485 - (3,698,485) - Other long-term assets 182,623 167,756 - 350,379 Total assets $ 13,136,923 $ 12,867,834 $ (13,362,881) $ 12,641,876 LIABILITIES AND EQUITY Accounts payable - related parties $ 1,162,297 $ 8,502,099 $ (9,664,396) $ - Other current liabilities 69,514 526,906 - 596,420 Long-term debt 3,332,188 - - 3,332,188 Other long-term liabilities 1,630,373 140,344 - 1,770,717 Equity 6,942,551 3,698,485 (3,698,485) 6,942,551 Total liabilities and equity $ 13,136,923 $ 12,867,834 $ (13,362,881) $ 12,641,876 Condensed Consolidating Balance Sheet December 31, 2014 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 282,609 74,761 - 357,370 Total assets $ 11,607,943 $ 12,101,576 $ (11,957,739) $ 11,751,780 LIABILITIES AND EQUITY Accounts payable - related parties $ 1,201,950 $ 6,670,744 $ (7,872,694) $ - Other current liabilities 55,318 1,209,309 - 1,264,627 Long-term debt 3,469,137 - - 3,469,137 Other long-term liabilities 1,600,750 136,478 - 1,737,228 Equity 5,280,788 4,085,045 (4,085,045) 5,280,788 Total liabilities and equity $ 11,607,943 $ 12,101,576 $ (11,957,739) $ 11,751,780 Condensed Consolidating Statement of Operations For the Year Ended December 31, 2015 Parent Subsidiary Consolidating (in thousands) Issuer Guarantors Entries Total Total operating revenues $ - $ 1,803,573 $ - $ 1,803,573 Total operating costs and expenses 697,247 (2,119,817) - (1,422,570) Income (loss) from operations 697,247 (316,244) - 381,003 Interest expense (213,416) (1,968) - (215,384) Other, net (386,560) (68,348) 386,560 (68,348) Income (loss) before income taxes 97,271 (386,560) 386,560 97,271 Income tax expense (31,371) - - (31,371) Net income (loss) $ 65,900 $ (386,560) $ 386,560 $ 65,900 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 Cash Flows For the Year Ended December 31, 2015 Parent Issuer Subsidiary Guarantors Consolidating Entries (in thousands) Total Net cash flows provided by (used in) operating activities $ (2,026,206) $ 2,923,711 $ - $ 897,505 Net cash flows provided by (used in) investing activities 632,916 (2,602,641) - (1,969,725) Net cash flows provided by (used in) financing activities 1,393,290 (92,541) - 1,300,749 Net increase in cash and cash equivalents - 228,529 - 228,529 Cash and cash equivalents at beginning of period - 21 - 21 Cash and cash equivalents at end of period $ - $ 228,550 $ - $ 228,550 Condensed Consolidating Statement of Cash Flows For the Year Ended December 31, 2014 Parent Subsidiary Consolidating (in thousands) Issuer Guarantors Entries 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 increase (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

Subsequent events

Subsequent events	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent events	Note 17 . Subsequent events Asset acquisition. In January 2016, the Company entered into an asset purchase agreement to acquire 80 percent of the seller’s interest in certain oil and natural gas properties and related assets in the southern Delaware Basin. As consideration for the acquisition, the Company agreed to issue to the seller approximately 2.2 million shares of common stock, $150.0 million in cash and $40.0 million to carry a portion of the seller’s future development costs in these properties. The acquisition is expected t o close during the first quarter of 2016, subject to customary closing conditions. Asset divestiture. In January 2016, the Company entered into an agreement to sell certain assets in the northern Delaware Basin for cash proceeds of approximately $290.0 mi llion. The sale is expected to close during the first quarter of 2016, subject to customary closing conditions. New commodity derivative contracts. After December 31, 2015 , 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) 2017: Volume (Bbl) 180,000 180,000 750,000 750,000 1,860,000 Price per Bbl $ 42.55 $ 42.55 $ 43.63 $ 43.63 $ 43.42 Oil Basis Swaps: (b) 2016: Volume (Bbl) 120,000 182,000 - - 302,000 Price per Bbl $ (0.25) $ (0.25) $ - $ - $ (0.25) 2017: Volume (Bbl) 360,000 242,000 2,024,000 2,024,000 4,650,000 Price per Bbl $ (0.41) $ (0.38) $ (0.38) $ (0.38) $ (0.38) (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 accoun25

Summary of significant accounting policies (Policies)	12 Months Ended
	Dec. 31, 2015
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. The Company consolidates the financial statements of these entities. All material intercompany balances and transactions have been eliminated.
Reclassification	Retrospective adjustments and reclassifications. Certain reclassifica tions have been made to the 2014 amounts in order to conform to the 2015 presentation and for the retrospective application resulting from the early adoption of Accounting Standards Update (“ASU”) No. 2015-03 and 2015-17 . The retrospective application of ASU 2015-03 resulted in $48.2 million of net deferred loan costs directly related to the Company’s senior notes being reclassified from a non current asset to a direct deduction from the carrying amount of the related senior notes at December 31, 2014. The retrospective application of ASU 2015-17 resulted in the current deferred income tax liability of $162.6 million at December 31, 2014 to be reclassified as a noncurrent deferred income tax liability in the Company’s consolidated balance sheet. Other certain prior period amounts have been reclassified to conform to the 2015 presentation. These reclassifications had no impact on the balance sheet, net income (loss) or cash flows.
Discontinued operations	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, before income tax expense of approximately $7.5 million. The Co mpany recognized income from discontinued operations, net of tax of $12.1 million for the year ended December 31, 2013 .
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 resul ts could differ from these estimates. Depletion of oi l 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 fut ure recoverable reserves , commodity price outlooks and prevailing market rates of other sources of income and costs . Other significant estimates inclu de, but are not limited to, asset retirement obligations, fair value of derivative financial instruments, fair value of business combinations, fair value of nonmonetary exchanges, 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 inves tments 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, m anagement 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 t he 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 allowance s 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 n ot 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 $ 1.2 million and $ 0.7 million at December 31, 2015 and December 31, 2014 , respectively .
Inventory	Inventory. Inventory consists primarily of tubular goods , water and other oilfield equipment that the Company plans to utilize in its ongoing exploration and develop ment 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 method and straight-line methods. For the interim period ended December 31, 2015 , the Company early adopted ASU No. 2015-03, “Interest-Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs,” which requires net deferred loan costs directly related to the Company’s senior notes to be classified as a direct deduction from the carryin g amount of the related senior notes. The Company retrospectively adopted the ASU and reclassified $ 48.2 million at December 31, 2014 from a non current asset to a deduction from long-term debt. The deferred loan costs related to the Co mpany’s credit facility remain classified as a non current asset due to the revolving nature of that facility. The provisions of the ASU were adopted primarily to simplify the required reporting for subsequent registration filings. The Company had deferred loan costs related to its senior notes of $ 42.9 million and $ 48.2 million, net of accumulated amortization of $ 18.7 million and $ 13.4 million, as a reduction of long-term debt at Decemb er 31, 2015 an d December 31, 2014 , respectively. The Company had deferred loan costs related to the credit facility of $ 15.6 million and $ 20.3 million, net of accumulated amortization of $ 51.0 millio n and $ 46.3 million, in non current assets at December 31, 2015 and December 31, 2014 , 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 and integ rated assets is based on the unit-of-production method using proved dev eloped reserves . During the years ended December 31, 2015 , 2014 and 2013 , the Company recognized depletion expense from continuing operations of $ 1,203.5 million, $ 960.9 million and $ 756.0 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 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 pro ject. 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 c ommercial viability. In these instances, the project ’ s feasibility is not contingent upon price improvements or advances in technology, but rather the C ompany’ s ongoing efforts and expenditures related to accurately predicting the hydrocarbon recoverabilit y based on well information, ga ining 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 consta ntly. 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 additio nal in formation 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 depletio n. 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 d epletion 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 unti l such projects ar e ready for their intended use. During the y ears ended December 31, 2015 and 2014 , the Company had capitalized interest of $ 0.7 million and $ 1.4 million, respectively. The Company did not capitalize interest during 2013 . 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 i s 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 val ue 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 b ase. 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 and integrated assets would be recognized at that time. Estimating future cash flows involves the use of judgments, includ ing 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 and cash flows from integrated assets . The Com pan y recognized impairment expense of $ 60.5 million, $ 447.2 million , and $ 65.4 million during the years ended December 31, 2015 , 2014 and 2013 , respectively, related to its proved oil and natura l gas properties. 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, 2015 , 2014 and 2013 , the Company recognized expense of $ 34.5 million, $ 217.3 million and $ 49.8 million, respectively, related to abandoned pro spects 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 equ ipment 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 $ 178.5 million and $ 129.1 million, net of accumulated depreciation of $ 54.4 million and $ 52.5 millio n, at December 31, 2015 and December 31, 2014 , respectively. During the years ended December 31, 2015 , 2014 and 2013 , the Company recognized depreciation expense of $ 18.3 million, $ 17.3 million and $ 15.2 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, 2015 and 2014 , respectively : December 31, (in thousands) 2015 2014 Gross intangible - operating rights $ 36,557 $ 36,557 Accumulated amortization (10,864) (9,403) Net intangible - operating rights $ 25,693 $ 27,154 The following table reflects amortization expense from continuing operations for the years ended December 31, 2015 , 2014 and 2013 : Years Ending December 31, (in thousands) 2015 2014 2013 Amortization expense $ 1,461 $ 1,461 $ 1,461 The following table reflects the estimated aggregate amortization expense for each of the periods presented below at December 31, 2015 : (in thousands) 2016 $ 1,461 2017 1,461 2018 1,461 2019 1,461 2020 1,461 Thereafter 18,388 Total $ 25,693
Equity method investment	Equity method investment s . 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 has the option to purchase the member interest of the other investor in ACC. This purchase option becomes exercisable three months after the completion date of the pipeline and remains exercisable for a period of twelve months. The Company accounts for its investm ent in ACC under the equity method of accounting for investments in unconsolidated affiliates. The Co mpany’s net investment in ACC was approximately $ 98.9 million and $ 29.5 million at December 31, 2015 and December 31, 2014 , respectively, and was included in other assets in the Company’s consolidated balance sheet. The equity loss for the years ended December 31, 2015 and 2014 was approximately $ 4.1 million and $ 1.3 million , respectively, and wa s included in other expense in the Company’s consolidated statement of operations. During 2015 and 2014 , the Company recorded approximately $ 2.9 million and $ 0.7 million, respectively, of capitalized interest on its 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 paymen ts is fixed and readily determinable. At December 31, 2015 and 2014 , the Company has accrued approximately $ 1.0 million and $ 1.7 million, respectively, related to environmental liabilities. During the years ended December 31, 2015 , 2014 and 2013 , the Company recognized environmental charges of approximately $ 2.7 million, $ 4.0 million and $ 3.4 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, 2015 , 2014 or 2013 . The Company may also enter into physical d elivery 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 Compa ny’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 rel ated 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 incre ase in the carrying amount of the liability and as corresponding accretion expense. Based on certain factors including commodity prices and costs, the Company may revise its previous estimates related to the liability, which would also increase or decrease the associated oil and gas property asset.
Treasury stock	Treasury stock. Treasury stock purchases are recorded at cost.
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 imbala nces. Oil and n atural 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. I mbalances 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 Com pany 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 re corded 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, 2015 or 2014 .
General and administrative expense.	General and administrative expense . The Company receiv es fe es for the operation of jointly- owned oil and natural gas properties and records such reimbursements as reductions of general and administrative expense. Such fees totaled approximately $ 24.3 million, $ 23.2 million and $ 18.5 million for the years e nded December 31, 2015 , 2014 and 2013 , 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 a n 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 price s 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. In November 2015, the FASB issued ASU No. 2015-17, “Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes,” which requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. The Company early adopted the ASU retrospectively for the interim period ended December 31, 2015, which resulted in its current deferred income tax liability of $162.6 million at December 31, 2014 to be reclassified as a noncurrent deferred income tax liability in the Company’s consolidated balance sheet. The provisions of the ASU were adopted primarily to simplify the required reporting for subsequent registration filings. The Company previously classified deferred incom e tax liabilities and assets separately to current and noncurrent. 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 effe ct 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 cons olidated financial statements. To recognize a tax position, the Company determines whether it is more likely than not that the tax posi tions will be sustained upon examination, including resolution of any related appeals or litigation, based on the te chnical 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 consol idated 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 b eing realized upon settlement. The Comp any had no material uncertain tax positions that required recognition in the consolidated financial statements at December 31, 2015 and 2014 . Any interest or penalties would be recognized as a component of income tax expense.
Recent accounting pronouncements	Recent accounting prono uncements. In May 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” which outlines a new, single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersede s 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. In August 2015, the FASB issued ASU No. 2015-14, “Revenue from Contracts with Custo mers (Topic 606): Deferral of the Effective Date,” which deferred the effective date of ASU 2014-09 by one year. That new standard is now effective for annual reporting periods beginning after December 15, 2017. 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 fi nancial statements. The Company is evaluating the impact that this new guidance will have on its consolidated financial statements.

Summary of significant accoun26

Summary of significant accounting policies (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Schedule of Finite-Lived Intangible Assets [Table Text Block]	The following table reflects the gross and net intangible assets at December 31, 2015 and 2014 , respectively : December 31, (in thousands) 2015 2014 Gross intangible - operating rights $ 36,557 $ 36,557 Accumulated amortization (10,864) (9,403) Net intangible - operating rights $ 25,693 $ 27,154
Schedule Of Amortization Expense [Table Text Block]	The following table reflects amortization expense from continuing operations for the years ended December 31, 2015 , 2014 and 2013 : Years Ending December 31, (in thousands) 2015 2014 2013 Amortization expense $ 1,461 $ 1,461 $ 1,461
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, 2015 : (in thousands) 2016 $ 1,461 2017 1,461 2018 1,461 2019 1,461 2020 1,461 Thereafter 18,388 Total $ 25,693

Exploratory well costs (Tables)

Exploratory well costs (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Beginning capitalized exploratory well costs $ 241,657 $ 144,504 $ 118,806 Additions to exploratory well costs pending the determination of proved reserves 102,846 234,057 130,967 Reclassifications due to determination of proved reserves (227,746) (99,657) (94,114) Exploratory well costs charged to expense (559) (37,247) (11,155) Ending capitalized exploratory well costs $ 116,198 $ 241,657 $ 144,504
Aging of capitalized exploratory well costs based on the date drilling was completed	The following table provides an aging at December 31, 2015 and 2014 of capitalized exploratory well costs based on the date drilling was completed: December 31, (dollars in thousands) 2015 2014 Capitalized exploratory well costs that have been capitalized for a period of one year or less $ 98,764 $ 232,346 Capitalized exploratory well costs that have been capitalized for a period greater than one year 17,434 9,311 Total capitalized exploratory well costs $ 116,198 $ 241,657 Number of projects with exploratory well costs that have been capitalized for a period greater than one year 8 7

Asset retirement obligations (T

Asset retirement obligations (Tables)	12 Months Ended
	Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset retirement obligations	The Company’s asset retirement obligation transactions during the years ended December 31, 2015 , 2014 and 2013 are summarized in the table below: Years Ended December 31, (in thousands) 2015 2014 2013 Asset retirement obligations, beginning of period $ 119,881 $ 101,593 $ 86,261 Liabilities incurred from new wells 4,052 5,324 6,338 Liabilities assumed in acquisitions 2,434 4,065 593 Accretion expense 7,600 7,072 6,047 Liabilities settled upon plugging and abandoning wells (2,736) (2,926) (3,447) Revision of estimates (a) (11,286) 4,753 5,801 Asset retirement obligations, end of period $ 119,945 $ 119,881 $ 101,593 (a) The downward revision to the Company’s asset retirement obligation estimates for the year ended December 31, 2015 is primarily due to a reduction in the future estimated abandonment costs.

Incentive plans (Tables)

Incentive plans (Tables)	12 Months Ended
	Dec. 31, 2015
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 year ended D ecember 31, 2015 is presented below: Weighted Average Number of Grant Date Restricted Fair Value Shares Per Share Restricted stock: Outstanding at December 31, 2014 1,091,309 $ 106.33 Shares granted 452,436 $ 109.76 Shares cancelled / forfeited (33,124) $ 111.08 Lapse of restrictions (310,974) $ 96.15 Outstanding at December 31, 2015 1,199,647 $ 110.14
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, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Fair value for awards granted during the period (a) $ 49,659 $ 57,940 $ 44,947 Fair value for awards vested during the period $ 35,700 $ 59,226 $ 21,496 Stock-based compensation expense from restricted stock $ 43,185 $ 36,585 $ 30,984 Income tax benefit related to restricted stock $ 16,049 $ 13,672 $ 11,650 (a) The weighted average grant date fair value per share amounts were $109.76, $129.12 and $88.19 for the years ended December 31, 2015, 2014 and 2013, respectively. 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 t he Company’s stock option award activity under the Plan for the years ended December 31, 2015 , 2014 and 2013 is presented below: Years Ended December 31, 2015 2014 2013 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 47,713 $ 17.49 255,537 $ 21.50 429,879 $ 20.28 Options exercised (4,812) $ 12.00 (207,824) $ 22.42 (174,342) $ 18.48 Outstanding at end of period 42,901 $ 18.10 47,713 $ 17.49 255,537 $ 21.50 Vested and exercisable at end of period 42,901 $ 18.10 47,713 $ 17.49 255,537 $ 21.50
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, 2015 : December 31, 2015 Weighted Intrinsic Average Weighted Value Range of Remaining Average of Exercise Number Contractual Exercise Options Prices Vested Life Price (in thousands) Vested and exercisable options: $12.00 - $12.85 15,824 1.54 years $ 12.81 1,267 $20.40 - $22.77 27,077 2.98 years $ 21.20 1,940 42,901 2.45 years $ 18.10 $ 3,207
Summarizes information about stock-based compensation for stock options	The following table shows the deductions in current taxable income related to stock options exercised for the years ended December 31, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Deductions in current taxable income related to stock options exercised $ 415 $ 23,208 $ 13,193
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, 2015 , 2014 and 2013 :
Summary of the Company's performance unit activity	The following table summarizes the performance unit activity for the year ended December 31, 2015 : Number of Grant Date Units Fair Value Performance units: Outstanding at December 31, 2014 250,314 $ 127.07 Units granted (a) 176,330 $ 156.86 Units vested (b) (110,889) $ 111.40 Outstanding at December 31, 2015 315,755 $ 149.21 (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. (b) On December 31, 2015, the performance period ended for these performance units. Each unit converted into 1.625 shares representing 180,199 shares of common stock issued on January 4, 2016.
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, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Fair value for awards granted during the period $ 27,659 $ 19,455 $ 12,352 Stock-based compensation expense from performance units $ 19,888 $ 10,545 $ 4,080 Income tax benefit related to performance units $ 7,391 $ 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 s tock-bas ed compensation awards that we re outstanding at December 31, 2015 : Restricted Performance (in thousands) Stock Units Total 2016 $ 31,992 $ 15,734 $ 47,726 2017 18,189 9,219 27,408 2018 6,466 - 6,466 2019 286 - 286 2020 4 - 4 Total $ 56,937 $ 24,953 $ 81,890

Disclosures about fair value 30

Disclosures about fair value of financial instruments (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 and 2014 : December 31, 2015 December 31, 2014 Carrying Fair Carrying Fair (in thousands) Value Value Value Value Assets: Derivative instruments $ 819,536 $ 819,536 $ 752,700 $ 752,700 Liabilities: Credit facility $ - $ - $ 139,500 $ 131,068 $600 million 7.0% senior notes due 2021 (a) $ 592,414 $ 595,500 $ 591,213 $ 625,500 $600 million 6.5% senior notes due 2022 (a) $ 591,549 $ 579,000 $ 590,454 $ 628,500 $600 million 5.5% senior notes due 2022 (a) $ 592,899 $ 553,500 $ 592,061 $ 598,500 $1,550 million 5.5% senior notes due 2023 (a) $ 1,555,326 $ 1,453,005 $ 1,555,909 $ 1,573,875 (a) The carrying value includes associated deferred loan costs and any (discount) premium. See Note 2 for additional information regarding the Company’s retrospective adoption of ASU No. 2015-03.
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, 2015 and 2014 . The Company nets the fair value of derivative instruments by counterparty in the Company’s consolidated balance sheets. December 31, 2015 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 $ - $ 684,029 $ - $ 684,029 $ (31,531) $ 652,498 Noncurrent: Commodity derivatives - 175,267 - 175,267 (8,229) 167,038 Liabilities Current: Commodity derivatives - (31,531) - (31,531) 31,531 - Noncurrent: Commodity derivatives - (8,229) - (8,229) 8,229 - Net derivative instruments $ - $ 819,536 $ - $ 819,536 $ - $ 819,536 December 31, 2014 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
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 December 2015 $ 104,982 $ 52,041 $ 52,941 September 2015 $ 18,023 $ 10,435 $ 7,588 December 2014 $ 677,021 $ 245,346 $ 431,675 September 2014 $ 26,790 $ 11,314 $ 15,476 June 2013 $ 84,140 $ 18,765 $ 65,375

Derivative financial instrume31

Derivative financial instruments (Tables)	12 Months Ended
	Dec. 31, 2015
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 followin g table summarizes the gains ( losses ) reported in earnings related to the commodity derivative instruments for the years ended December 31, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Gain (loss) on derivatives: Oil derivatives $ 675,303 $ 869,421 $ (133,890) Natural gas derivatives 24,449 21,496 10,238 Total $ 699,752 $ 890,917 $ (123,652) The following table represents the Company’s cash receipts from (payments on) derivatives for the years ended December 31, 2015, 2014 and 2013: Years Ended December 31, (in thousands) 2015 2014 2013 Cash receipts from (payments on) derivatives: Oil derivatives $ 597,297 $ 76,335 $ (41,616) Natural gas derivatives 35,619 (4,352) 9,275 Total $ 632,916 $ 71,983 $ (32,341)
Company's outstanding derivative contracts	Commodity derivative contracts at December 31, 2015 . The following table sets forth the Company’s outstanding derivative contracts at December 31, 2015 . When aggregating multiple contracts, the weighted average contract price is disclosed. All of the Company’s derivative contracts at December 31, 2015 are expected to settle by Dec ember 31, 2017. First Second Third Fourth Quarter Quarter Quarter Quarter Total Oil Swaps: (a) 2016: Volume (Bbl) 6,722,000 5,985,000 5,460,000 5,054,000 23,221,000 Price per Bbl $ 71.99 $ 73.38 $ 74.21 $ 59.38 $ 70.13 2017: Volume (Bbl) 4,354,000 4,118,000 2,655,000 2,655,000 13,782,000 Price per Bbl $ 61.59 $ 62.03 $ 55.23 $ 55.23 $ 59.27 Oil Basis Swaps: (b) 2016: Volume (Bbl) 6,035,000 5,732,000 5,520,000 5,060,000 22,347,000 Price per Bbl $ (1.49) $ (1.50) $ (1.46) $ (1.48) $ (1.48) 2017: Volume (Bbl) 3,780,000 3,822,000 1,012,000 1,012,000 9,626,000 Price per Bbl $ (1.32) $ (1.32) $ (0.54) $ (0.54) $ (1.16) Natural Gas Swaps: (c) 2016: Volume (MMBtu) 7,280,000 7,280,000 7,360,000 7,360,000 29,280,000 Price per MMBtu $ 3.02 $ 3.02 $ 3.02 $ 3.02 $ 3.02 (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.

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Company's debt	Note 9 . Debt The Company’s debt consisted of the following at December 31, 2015 and 2014 : December 31, (in thousands) 2015 2014 Credit facility $ - $ 139,500 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 25,073 27,820 Deferred loan costs, net (42,885) (48,183) Less: current portion - - Total long-term debt $ 3,332,188 $ 3,469,137
Principal maturities of debt	Principal maturities of long -term debt outstanding at December 31, 2015 were as follows: (in thousands) 2016 $ - 2017 - 2018 - 2019 - 2020 - Thereafter 3,350,000 Total $ 3,350,000
Interest expense	The following amounts have been incurred and charged to interest expense for the years ended December 31, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Cash payments for interest $ 211,443 $ 211,342 $ 200,961 Amortization of original issue discount (premium) (2,747) (2,599) (1,248) Amortization of deferred loan origination costs 9,971 10,937 13,172 Accretion expense 1,795 - - Net changes in accruals (165) (737) 5,696 Interest costs incurred 220,297 218,943 218,581 Less: capitalized interest (4,913) (2,282) - Total interest expense $ 215,384 $ 216,661 $ 218,581

Commitments and contingencies (

Commitments and contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Summary of the Company's future commitments	The following table summarizes the Company’s commitments at December 31, 2015 : (in thousands) 2016 $ 51,710 2017 21,256 2018 21,148 2019 13,196 2020 7,335 Thereafter 45,451 Total $ 160,096
Future minimum lease commitments under non-cancellable operating leases	Future minimu m lease commitments under non-cancellable operating leases at December 31, 2015 were as follows: (in thousands) 2016 $ 7,941 2017 7,877 2018 7,087 2019 5,651 2020 4,738 Thereafter 5,091 Total $ 38,385

Income taxes (Tables)

Income taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
The Company's 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, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Income from continuing operations $ 31,371 $ 317,785 $ 118,237 Income from discontinued operations - - 7,518 Changes in stockholders’ equity: Excess tax benefits related to stock-based compensation (2,150) (16,480) (6,147) $ 29,221 $ 301,305 $ 119,608
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, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Current: U.S. federal $ 127 $ 16,621 $ 12,504 U.S. state and local 1,622 4,997 3,306 Total current income tax provision 1,749 21,618 15,810 Deferred: U.S. federal 40,364 278,615 119,985 U.S. state and local (10,742) 17,552 (17,558) Total deferred income tax provision 29,622 296,167 102,427 Total income tax provision attributable to income from continuing operations $ 31,371 $ 317,785 $ 118,237
reconciliation between the income tax expense computed by multiplying pretax income from continuing operations	The reconciliation between the income tax expense computed by multiplying pre- tax 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) 2015 2014 2013 Income at U.S. federal statutory rate $ 34,045 $ 299,586 $ 125,006 State income taxes (net of federal tax effect) 3,071 22,826 12,505 Revisions of previous estimates (631) 738 1,400 Change in estimated effective statutory state income tax (9,026) (7,945) (21,876) Nondeductible expense & other 3,912 2,580 1,202 Income tax expense $ 31,371 $ 317,785 $ 118,237 Effective tax rate 32.3% 37.1% 33.1%
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 year ended December 31, 2013 : Year Ended (in thousands) December 31, 2013 Current: U.S. federal $ 144 U.S. state and local 25 Total current income tax provision 169 Deferred: U.S. federal 6,397 U.S. state and local 952 Total deferred income tax provision 7,349 Total income tax provision attributable to income from discontinued operations $ 7,518
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) 2015 2014 Deferred tax assets: Stock-based compensation $ 36,738 $ 24,810 Asset retirement obligation 44,573 44,802 Other 29,574 28,925 Total deferred tax assets 110,885 98,537 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 (1,420,275) (1,401,313) Intangible assets - operating rights (9,548) (10,148) Derivative instruments (304,550) (281,303) Other (6,885) (6,524) Total deferred tax liability (1,741,258) (1,699,288) Net deferred tax liability $ (1,630,373) $ (1,600,751)

Major customers and derivativ35

Major customers and derivative counterparties (Tables)	12 Months Ended
	Dec. 31, 2015
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 during the years ended December 31, 2015 , 2014 and 2013 : Years Ended December 31, 2015 2014 2013 Holly Frontier Refining and Marketing, LLC 25% 17% 30% Enterprise Crude Oil LLC 12% 12% 13% Plains Marketing and Transportation, Inc. 11% 6% 4% Western Refining Company LP 5% 12% 1%

Related party transactions (Tab

Related party transactions (Tables)	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Summary of charges incurred with and payments made to and received from the Company's related parties and reported in the consolidated statements of operations	The following table summarize s charges incurred with and payments made to related parties and reported in the Company’s consol idated statements of operations for the periods presented: Years Ended December 31, (in thousands) 2015 2014 2013 Amounts paid to a partnership in which a director has an ownership interest (a) $ 5,745 $ 15,181 $ 7,255 Amounts paid to a director and certain officers of the Company (b) $ 593 $ 383 $ 43 Amounts paid under consulting agreement with Steven L. Beal (c) $ - $ - $ 865 Amounts received from a director and certain officers of the Company (d) $ 237 $ 169 $ 84 (a) 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. (b) Amounts include revenue interests, overriding royalty interests and net profits interests in properties owned by the Company made to a director and certain officers (or affiliated entities). Amounts also include payments for an acreage acquisition and lease bonuses to an affiliated entity of an office r. (c) 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. Be al 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. (d) Amounts include p ayments to the Company as a result of activity on oil and natural gas properties in which a director and certain officers (or affiliated entities) have an interest.

Net income per share (Tables)

Net income per share (Tables)	12 Months Ended
	Dec. 31, 2015
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 discontinu ed operations and net income attributable to common stockholders to the basic and diluted earnings used to determine the Company’s income per shar e amounts for t he years ended December 31, 2015 , 2014 and 2013 , respectively, under the two-class me thod : Years Ended December 31, (in thousands, except per share amounts) 2015 2014 Income as reported $ 65,900 $ 538,175 Participating basic earnings (635) (5,961) Basic income attributable to common stockholders 65,265 532,214 Reallocation of participating earnings 2 16 Diluted income attributable to common stockholders $ 65,267 $ 532,230 Income per common share: Basic $ 0.54 $ 4.89 Diluted $ 0.54 $ 4.88 Year Ended December 31, 2013 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
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, 2015 , 2014 and 2013 : Years Ended December 31, (in thousands) 2015 2014 2013 Weighted average common shares outstanding: Basic 119,926 108,844 103,744 Dilutive common stock options 25 83 165 Dilutive performance units 422 205 4 Diluted 120,373 109,132 103,913
summary of the performance units that were not included in the computation of diluted net income per share	The following table is a summary of the 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) 2015 2014 2013 Number of antidilutive common shares: Antidilutive performance units - - 83

Other current liabilities (Tabl

Other current liabilities (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 and 2014 : December 31, (in thousands) 2015 2014 Other current liabilities: Accrued production costs $ 70,876 $ 70,786 Payroll related matters 29,411 34,349 Accrued interest 68,925 69,264 Asset retirement obligations 8,626 9,146 Other 7,072 11,763 Other current liabilities $ 184,910 $ 195,308

Subsidiary guarantors (Tables)

Subsidiary guarantors (Tables)	12 Months Ended
	Dec. 31, 2015
Guarantees [Abstract]
Condensed Consolidating Balance Sheet	The following condensed consolidating balance s heets at December 31, 2015 and 2014 , condensed c o nsolidating sta tements of o perations and condensed consolidating statements of cash flows for the years ended December 31, 2015 , 2014 and 2013 , present financial information fo r Concho Resources Inc. as the p arent on a stand-alone basis (carrying any investment s in subsidiaries under the equity method), financial information for the subsidiary guarantors 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 are not restricted from making distributions to the Company. Condensed Consolidating Balance Sheet December 31, 2015 Parent Subsidiary Consolidating (in thousands) Issuer Guarantors Entries Total ASSETS Accounts receivable - related parties $ 8,502,099 $ 1,162,297 $ (9,664,396) $ - Other current assets 753,716 560,834 - 1,314,550 Oil and natural gas properties, net - 10,798,497 - 10,798,497 Property and equipment, net - 178,450 - 178,450 Investment in subsidiaries 3,698,485 - (3,698,485) - Other long-term assets 182,623 167,756 - 350,379 Total assets $ 13,136,923 $ 12,867,834 $ (13,362,881) $ 12,641,876 LIABILITIES AND EQUITY Accounts payable - related parties $ 1,162,297 $ 8,502,099 $ (9,664,396) $ - Other current liabilities 69,514 526,906 - 596,420 Long-term debt 3,332,188 - - 3,332,188 Other long-term liabilities 1,630,373 140,344 - 1,770,717 Equity 6,942,551 3,698,485 (3,698,485) 6,942,551 Total liabilities and equity $ 13,136,923 $ 12,867,834 $ (13,362,881) $ 12,641,876 Condensed Consolidating Balance Sheet December 31, 2014 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 282,609 74,761 - 357,370 Total assets $ 11,607,943 $ 12,101,576 $ (11,957,739) $ 11,751,780 LIABILITIES AND EQUITY Accounts payable - related parties $ 1,201,950 $ 6,670,744 $ (7,872,694) $ - Other current liabilities 55,318 1,209,309 - 1,264,627 Long-term debt 3,469,137 - - 3,469,137 Other long-term liabilities 1,600,750 136,478 - 1,737,228 Equity 5,280,788 4,085,045 (4,085,045) 5,280,788 Total liabilities and equity $ 11,607,943 $ 12,101,576 $ (11,957,739) $ 11,751,780
Condensed Consolidating Statement of Operations	The following condensed consolidating balance s heets at December 31, 2015 and 2014 , condensed c o nsolidating sta tements of o perations and condensed consolidating statements of cash flows for the years ended December 31, 2015 , 2014 and 2013 , present financial information fo r Concho Resources Inc. as the p arent on a stand-alone basis (carrying any investment s in subsidiaries under the equity method), financial information for the subsidiary guarantors 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 are not restricted from making distributions to the Company. Condensed Consolidating Statement of Operations For the Year Ended December 31, 2015 Parent Subsidiary Consolidating (in thousands) Issuer Guarantors Entries Total Total operating revenues $ - $ 1,803,573 $ - $ 1,803,573 Total operating costs and expenses 697,247 (2,119,817) - (1,422,570) Income (loss) from operations 697,247 (316,244) - 381,003 Interest expense (213,416) (1,968) - (215,384) Other, net (386,560) (68,348) 386,560 (68,348) Income (loss) before income taxes 97,271 (386,560) 386,560 97,271 Income tax expense (31,371) - - (31,371) Net income (loss) $ 65,900 $ (386,560) $ 386,560 $ 65,900 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 Cash Flows	The following condensed consolidating balance s heets at December 31, 2015 and 2014 , condensed c o nsolidating sta tements of o perations and condensed consolidating statements of cash flows for the years ended December 31, 2015 , 2014 and 2013 , present financial information fo r Concho Resources Inc. as the p arent on a stand-alone basis (carrying any investment s in subsidiaries under the equity method), financial information for the subsidiary guarantors 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 are not restricted from making distributions to the Company. Condensed Consolidating Statement of Cash Flows For the Year Ended December 31, 2015 Parent Issuer Subsidiary Guarantors Consolidating Entries (in thousands) Total Net cash flows provided by (used in) operating activities $ (2,026,206) $ 2,923,711 $ - $ 897,505 Net cash flows provided by (used in) investing activities 632,916 (2,602,641) - (1,969,725) Net cash flows provided by (used in) financing activities 1,393,290 (92,541) - 1,300,749 Net increase in cash and cash equivalents - 228,529 - 228,529 Cash and cash equivalents at beginning of period - 21 - 21 Cash and cash equivalents at end of period $ - $ 228,550 $ - $ 228,550 Condensed Consolidating Statement of Cash Flows For the Year Ended December 31, 2014 Parent Subsidiary Consolidating (in thousands) Issuer Guarantors Entries 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 increase (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

Subsequent events (Tables)

Subsequent events (Tables)	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
New commodity derivative contracts	After December 31, 2015 , 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) 2017: Volume (Bbl) 180,000 180,000 750,000 750,000 1,860,000 Price per Bbl $ 42.55 $ 42.55 $ 43.63 $ 43.63 $ 43.42 Oil Basis Swaps: (b) 2016: Volume (Bbl) 120,000 182,000 - - 302,000 Price per Bbl $ (0.25) $ (0.25) $ - $ - $ (0.25) 2017: Volume (Bbl) 360,000 242,000 2,024,000 2,024,000 4,650,000 Price per Bbl $ (0.41) $ (0.38) $ (0.38) $ (0.38) $ (0.38) (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 Accoun41

Summary Of Significant Accounting Policies (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended					12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Summary Of Significant Accounting Policies Narrative [Abstract]
Deferred loan costs, net	$ 42,885		$ 48,183			$ 42,885	$ 48,183
Current deferred income tax liability			162,600				162,600
Allowance for Doubtful Accounts Receivable	1,200		700			1,200	700
Accumulated amortization of reclassified deferred loan costs						18,700	13,400
Deferred loan costs	15,585		20,260			15,585	20,260
Accumulated amortization						$ 51,000	46,300
Estimated economic life of gross operating rights in years						25 years
Depletion expense from continuing and discontuned operations						$ 1,203,500	960,900	$ 756,000
Impairment Of Oil And Gas Properties	52,941	$ 7,588	431,675	$ 15,476	$ 65,375	60,500	447,200	65,400
Impairment of Leasehold						34,500	217,300	49,800
Other property and equipment, net	178,450		129,136			178,450	129,136
Other property and equipment, accumulated depreciation	54,400		52,500			54,400	52,500
Depreciation expense on other property and equipment						18,300	17,300	15,200
Environmental liability accrued	1,000		1,700			1,000	1,700
Environmental libility expensed						2,700	4,000	3,400
Fees related to operation of jointly owned oil and natural gas properties						24,300	23,200	18,500
Interest costs capitalized on oil and gas properties						$ 700	1,400	$ 0
Disposal Date						Jan. 1, 2016		Dec. 15, 2012
Net Proceeds								$ 503,100
Pre-tax gain on sale of assets of discontinued operations								900
Gain on Sale of Assets								19,600
Discontinued Operation Tax Effect Of Discontinued Operation								7,500
Income from discontinued operations, net of tax						$ 0	0	$ 12,081
Alpha Crude Connector [Member]
Equity Method Investments [Line Items]
Income (loss) from equity method investments						(4,100)	(1,300)
Interest costs capitalized on equity method investment						2,900	700
Total equity method investment	$ 98,900		$ 29,500			$ 98,900	$ 29,500
Equity method investment ownership percentage	50.00%					50.00%
Other [Member]
Equity Method Investments [Line Items]
Total equity method investment	$ 20,800					$ 20,800
Equity method investment ownership percentage	25.00%					25.00%

Summary Of Significant Accoun42

Summary Of Significant Accounting Policies (Gross And Net Intangible Assets) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Disclosure Summary Of Significant Accounting Policies Gross And Net Intangible Assets [Abstract]
Gross intangible - operating rights	$ 36,557	$ 36,557
Accumulated amortization	(10,864)	(9,403)
Net intangible - operating rights	$ 25,693	$ 27,154

Summary Of Significant Accoun43

Summary Of Significant Accounting Policies (Amortization Expense) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Summary Of Significant Accounting Policies Amortization Expense [Abstract]
Amortization expense	$ 1,461	$ 1,461	$ 1,461

Summary Of Significant Accoun44

Summary Of Significant Accounting Policies (Estimated Future Aggregate Amortization Expense) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Disclosure Summary Of Significant Accounting Policies Estimated Future Aggregate Amortization Expense [Abstract]
2,016	$ 1,461
2,017	1,461
2,018	1,461
2,019	1,461
2,020	1,461
Thereafter	18,388
Net intangible - operating rights	$ 25,693	$ 27,154

Exploratory Well Costs (Capital

Exploratory Well Costs (Capitalized Exploratory Well Activity) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Exploratory Well Costs Capitalized Exploratory Well Activity [Abstract]
Beginning capitalized exploratory well costs	$ 241,657	$ 144,504	$ 118,806
Additions to exploratory well costs pending the determination of proved reserves	102,846	234,057	130,967
Reclassifications due to determination of proved reserves	(227,746)	(99,657)	(94,114)
Exploratory well costs charged to expense	(559)	(37,247)	(11,155)
Ending capitalized exploratory well costs	$ 116,198	$ 241,657	$ 144,504

Exploratory Well Costs (Aging O

Exploratory Well Costs (Aging Of Capitalized Exploratory Well Costs Based On The Date Of Drilling) (Detail) $ in Thousands	Dec. 31, 2015USD ($)Number	Dec. 31, 2014USD ($)Number	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)
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	$ 98,764	$ 232,346
Capitalized exploratory well costs that have been capitalized for a period greater than one year	17,434	9,311
Total capitalized exploratory well costs	$ 116,198	$ 241,657	$ 144,504	$ 118,806
Projects that have Exploratory Well Costs that have been Capitalized for Period Greater than One Year, Number of Projects | Number	8	7

Exploratory Well Costs (Narrati

Exploratory Well Costs (Narrative) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Oil And Gas In Process Activities [Line Items]
Capitalized Exploratory Well Costs That Have Been Capitalized For Period Greater Than One Year	$ 17,434	$ 9,311
Delaware Basin Area [Member]
Oil And Gas In Process Activities [Line Items]
Capitalized Exploratory Well Costs That Have Been Capitalized For Period Greater Than One Year	7,200
Delaware Basin Area - Other Project [Member]
Oil And Gas In Process Activities [Line Items]
Capitalized Exploratory Well Costs That Have Been Capitalized For Period Greater Than One Year	5,700
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	4,500
OBO Projects - Projects Drilled in 2012 [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

Acquisitions And Business Com48

Acquisitions And Business Combinations (Narrative) (Detail)	12 Months Ended
	Dec. 31, 2015USD ($)
Clayton Williams [Member]
Business Acquisition [Line Items]
Gain (loss) on disposition of assets	$ (50,000,000)

Asset Retirement Obligations (S

Asset Retirement Obligations (Schedule Of Asset Retirement Obligation Transactions) (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Asset Retirement Obligations Schedule Of Asset Retirement Obligation Transactions [Abstract]
Asset retirement obligations, beginning of period		$ 119,881	$ 101,593	$ 86,261
Liabilities incurred from new wells		4,052	5,324	6,338
Liabilities assumed in acquisitions		2,434	4,065	593
Accretion expense for continuing operations		7,600	7,072	6,047
Liabilities settled upon plugging and abandoning wells		(2,736)	(2,926)	(3,447)
Revision of estimates	[1]	(11,286)	4,753	5,801
Asset retirement obligations, end of period		$ 119,945	$ 119,881	$ 101,593
[1]	The downward revision to the Company’s asset retirement obligation estimates for the year ended December 31, 2015 is primarily due to a reduction in the future estimated abandonment costs.

Incentive Plans (Narrative) (De

Incentive Plans (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, employers contribution	$ 9.5	$ 8.1	$ 6.6
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value	$ 0.4	$ 23.2	$ 13.2
Performance unit awards vesting period	3 years
Approved and authorized awards	10,500,000
Awards available for future grant	2,900,000
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 (Summary Of Sto

Incentive Plans (Summary Of Stock Incentive Plan) (Detail) - shares	Dec. 31, 2015	Dec. 31, 2014
Disclosure Incentive Plans Summary Of Stock Incentive Plan [Abstract]
Treasury shares	306,061	260,124

Incentive Plans (Schedule Of Re

Incentive Plans (Schedule Of Restricted Stock Awards Activity) (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Incentive Plans Schedule Of Restricted Stock Awards Activity [Abstract]
Outstanding at beginning of period	1,091,309
Shares granted	452,436	448	499
Shares cancelled / forfeited	(33,124)
Lapse of restrictions	(310,974)
Outstanding at end of period	1,199,647	1,091,309
Weighted Average Grant Date Fair Value, Outstanding at beginning of year	$ 106.33
Shares Granted - Weighted Average Grant Date Fair Value Per Share	109.76	$ 129.12	$ 88.19
Shares cancelled / forfeited - Weighted Average Grant Date Fair Value per share	111.08
Lapse of Restrictions - Weighted Average Grant Date Fair Value per share	96.15
Weighted Average Grant Date Fair Value, Outstanding at end of year	$ 110.14	$ 106.33

Incentive Plans (Summary Inform

Incentive Plans (Summary Information For Stock-Based Compensation For Restricted Stock Awards) (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Granted - Weighted Average Grant Date Fair Value Per Share		$ 109.76	$ 129.12	$ 88.19
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value for awards granted during the period	[1]	$ 49,659,000	$ 57,940,000	$ 44,947,000
Fair value for awards vested during the period		35,700,000	59,226,000	21,496,000
Stock-based compensation expense from restricted stock		43,185,000	36,585,000	30,984,000
Income tax benefit related to restricted stock		$ 16,049,000	$ 13,672,000	$ 11,650,000
[1]	The weighted average grant date fair value per share amounts were $109.76, $129.12 and $88.19 for the years ended December 31, 2015, 2014 and 2013, respectively. 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) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Incentive Plans Schedule Of Stock Option Awards Activity [Abstract]
Outstanding at beginning of period (Shares)	47,713	255,537	429,879
Options exercised (Shares)	(4,812)	(207,824)	(174,342)
Outstanding at end of period (Shares)	42,901	47,713	255,537
Vested and exercisable at end of period (Shares)	42,901
Outstanding at beginning of period	$ 17.49	$ 21.5	$ 20.28
Options exercised	12	22.42	18.48
Outstanding at end of period	18.1	17.49	21.5
Vested and exercisable at end of period - weighted average exercise price	$ 18.1	$ 17.49	$ 21.5

Incentive Plans (Summary Info55

Incentive Plans (Summary Information For Vested And Exercisable Stock Options Outstanding) (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Vested and exercisable at end of period (Shares)	42,901
Weighted Average Remaining Contractual Life, Vested and exercisable options, years	2 years 5 months
Vested and exercisable at end of period - weighted average exercise price	$ 18.1	$ 17.49	$ 21.5
Intrinsic Value, Vested and exercisable options	$ 3,207
Range Three [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise price, Lower range	$ 12
Exercise price, Upper range	$ 12.85
Vested and exercisable at end of period (Shares)	15,824
Weighted Average Remaining Contractual Life, Vested and exercisable options, years	1 year 6 months
Vested and exercisable at end of period - weighted average exercise price	$ 12.81
Intrinsic Value, Vested and exercisable options	$ 1,267
Range Four [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise price, Lower range	$ 20.4
Exercise price, Upper range	$ 22.77
Vested and exercisable at end of period (Shares)	27,077
Weighted Average Remaining Contractual Life, Vested and exercisable options, years	2 years 12 months
Vested and exercisable at end of period - weighted average exercise price	$ 21.2
Intrinsic Value, Vested and exercisable options	$ 1,940

Incentive Plans (Summary Info56

Incentive Plans (Summary Information For Stock-Based Compensation For Stock Options) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Deductions in current taxable income related to stock options exercised	$ 415	$ 23,208	$ 13,193

Incentive Plans (Summary Of Ass

Incentive Plans (Summary Of Assumptions To Estimate Fair Value of Performance Unit Awards) (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Incentive Plans Schedule Of Performance Unit Awards Fair Value Assumptions [Abstract]
Risk-free interest rate	1.07%	0.76%	0.37%
Volatility assumption - minimum	26.10%	29.20%	31.50%
Volatility assumption - maximum	43.00%	42.20%	45.10%

Incentive Plans (Schedule Of Pe

Incentive Plans (Schedule Of Performance Unit Awards Activity) (Detail)	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Disclosure Incentive Plans Schedule Of Performance Unit Awards Activity [Abstract]
Performance units outstanding at beginning of period (Shares)	250,314
Units granted	176,330	[1]
Units vested	110,889	[2]
Performance units outstanding at end of period (Shares)	315,755
Weighted Average Grant Date Fair Value, Outstanding at beginning of year | $ / shares	$ 127.07
Shares Granted - Grant Date Fair Value - Performance Units | $ / shares	156.86	[1]
Shares Vested - Grant Date Fair Value - Performance Units | $ / shares	111.4	[2]
Weighted Average Grant Date Fair Value, Outstanding at end of year | $ / shares	$ 149.21
Performance Percentage Of Actual Payout Minimum	0.00%
Performance Percentage Of Actual Payout Maximum	300.00%
Number Of Shares Earned For Each Vested Award	180,199
[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.
[2]	On December 31, 2015, the performance period ended for these performance units. Each unit converted into 1.625 shares representing 180,199 shares of common stock issued on January 4, 2016.

Incentive Plans (Summary Info59

Incentive Plans (Summary Information For Stock-Based Compensation For Performance Units) (Detail) - Performance Shares [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value for awards granted during the period	$ 27,659	$ 19,455	$ 12,352
Stock-based compensation expense from performance units	19,888	10,545	4,080
Income tax benefit related to performance units	$ 7,391	$ 3,941	$ 1,560

Incentive Plans (Summary For Fu

Incentive Plans (Summary For Future Stock-Based Compensation Expense) (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
2,016	$ 47,726
2,017	27,408
2,018	6,466
2,019	286
2,020	4
Total	81,890
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
2,016	31,992
2,017	18,189
2,018	6,466
2,019	286
2,020	4
Total	56,937
Performance Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
2,016	15,734
2,017	9,219
2,018	0
2,019	0
2,020	0
Total	$ 24,953

Disclosures About Fair Value 61

Disclosures About Fair Value Of Financial Instruments (Carrying Amounts And Fair Values Of The Company's Financial Instruments) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Credit facility	$ 0	$ 139,500
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 [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	819,536	752,700
Credit facility	0	139,500
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	592,414	591,213
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	591,549	590,454
Carrying Reported Amount Fair Value Disclosure [Member] | Five Point Five Percent Unsecured Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	592,899	592,061
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	1,555,326	1,555,909
Portion At Fair Value Fair Value Disclosure [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Derivative instruments, Assets	819,536	752,700
Credit facility	0	131,068
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	595,500	625,500
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	579,000	628,500
Portion At Fair Value Fair Value Disclosure [Member] | Five Point Five Percent Unsecured Senior Notes [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Unsecured senior notes	553,500	598,500
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	$ 1,453,005	$ 1,573,875

Disclosures About Fair Value Me

Disclosures About Fair Value Measurements (Company's Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value Of Derivatives Disclosure Information [Line Items]
Current derivative contracts, assets	$ 652,498	$ 490,351
Noncurrent derivative contracts, assets	167,038	262,349
Net financial assets (liabilities)	819,536	752,700
Estimate Of Fair Value Fair Value Disclosure [Member]
Fair Value Of Derivatives Disclosure Information [Line Items]
Current derivative contracts, assets	684,029	501,717
Noncurrent derivative contracts, assets	175,267	262,349
Current derivative contracts, liabilities	(31,531)	(11,366)
Noncurrent derivative contracts, liabilities	(8,229)	0
Net financial assets (liabilities)	819,536	752,700
Gross Amounts Offset in Consolidated Balance Sheet [Member]
Fair Value Of Derivatives Disclosure Information [Line Items]
Current derivative contracts, assets	(31,531)	(11,366)
Noncurrent derivative contracts, assets	(8,229)	0
Current derivative contracts, liabilities	31,531	11,366
Noncurrent derivative contracts, liabilities	8,229	0
Net financial assets (liabilities)	0	0
Fair Value Inputs Level 1 [Member]
Fair Value Of Derivatives 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 financial assets (liabilities)	0	0
Fair Value Inputs Level 2 [Member]
Fair Value Of Derivatives Disclosure Information [Line Items]
Current derivative contracts, assets	684,029	501,717
Noncurrent derivative contracts, assets	175,267	262,349
Current derivative contracts, liabilities	(31,531)	(11,366)
Noncurrent derivative contracts, liabilities	(8,229)	0
Net financial assets (liabilities)	819,536	752,700
Fair Value Inputs Level 3 [Member]
Fair Value Of Derivatives 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 financial assets (liabilities)	$ 0	$ 0

Disclosures About Fair Value 63

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 ($) $ in Thousands	3 Months Ended					12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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	$ 104,982	$ 18,023	$ 677,021	$ 26,790	$ 84,140
Estimated Fair Value	52,041	10,435	245,346	11,314	18,765
Impairment Expense	$ 52,941	$ 7,588	$ 431,675	$ 15,476	$ 65,375	$ 60,500	$ 447,200	$ 65,400

Derivative Financial Instrume64

Derivative Financial Instruments (Gains And Losses Reported In Earnings Related To The Commodity And Interest Rate Derivative Instruments) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Financial Instruments Gains And Losses Reported In Earnings Related To Commodity And Interest Rate Derivative Instruments [Line Items]
Settlements received from (paid on) derivatives	$ 632,916	$ 71,983	$ (32,341)
Mark-to-market gain (loss)	699,752	890,917	(123,652)
Oil Commodity Derivative [Member]
Derivative Financial Instruments Gains And Losses Reported In Earnings Related To Commodity And Interest Rate Derivative Instruments [Line Items]
Settlements received from (paid on) derivatives	597,297	76,335	(41,616)
Mark-to-market gain (loss)	675,303	869,421	(133,890)
Natural Gas Commodity Derivative [Member]
Derivative Financial Instruments Gains And Losses Reported In Earnings Related To Commodity And Interest Rate Derivative Instruments [Line Items]
Settlements received from (paid on) derivatives	35,619	(4,352)	9,275
Mark-to-market gain (loss)	$ 24,449	$ 21,496	$ 10,238

Derivative Financial Instrume65

Derivative Financial Instruments (Outstanding Commodity Derivative Contracts) (Detail)		3 Months Ended				12 Months Ended
		Dec. 31, 2016MMBTUbbl$ / bbl$ / MMBTU	Sep. 30, 2016MMBTUbbl$ / bbl$ / MMBTU	Jun. 30, 2016MMBTUbbl$ / bbl$ / MMBTU	Mar. 31, 2016MMBTUbbl$ / bbl$ / MMBTU	Dec. 31, 2016MMBTUbbl$ / bbl$ / MMBTU
Oil Swaps [Member]
Derivative [Line Items]
Volume (Bbl/MMBtu) - Current Year | bbl	[1]	5,054,000	5,460,000	5,985,000	6,722,000	23,221,000
Price per Bbl/MMBtu - Current Year | $ / bbl	[1]	59.38	74.21	73.38	71.99	70.13
Volume (Bbl/MMBtu) - Year One | bbl	[1]	2,655,000	2,655,000	4,118,000	4,354,000	13,782,000
Price per Bbl/MMBtu - Year One | $ / bbl	[1]	55.23	55.23	62.03	61.59	59.27
Oil Basis Swaps [Member]
Derivative [Line Items]
Volume (Bbl/MMBtu) - Current Year | bbl	[2]	5,060,000	5,520,000	5,732,000	6,035,000	22,347,000
Price per Bbl/MMBtu - Current Year | $ / bbl	[2]	(1.48)	(1.46)	(1.5)	(1.49)	(1.48)
Volume (Bbl/MMBtu) - Year One | bbl	[2]	1,012,000	1,012,000	3,822,000	3,780,000	9,626,000
Price per Bbl/MMBtu - Year One | $ / bbl	[2]	(0.54)	(0.54)	(1.32)	(1.32)	(1.16)
Natural Gas Swap [Member]
Derivative [Line Items]
Volume (Bbl/MMBtu) - Current Year | MMBTU	[3]	7,360,000	7,360,000	7,280,000	7,280,000	29,280,000
Price per Bbl/MMBtu - Current Year | $ / MMBTU	[3]	3.02	3.02	3.02	3.02	3.02
[1]	The index prices for the oil price swaps are based on the NYMEX – West Texas Intermediate (“WTI”) monthly average futures price.the NYMEX – West Texas Intermediate monthly average futures price.
[2]	The basis differential price is between Midland – WTI and Cushing – WTI.
[3]	The index prices for the natural gas price swaps are based on the NYMEX – Henry Hub last trading day futures price.

Debt (Summary Of Long-Term Debt

Debt (Summary Of Long-Term Debt) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Credit facility	$ 0	$ 139,500
Unamortized original issue premium	25,073	27,820
Deferred loan costs, net	(42,885)	(48,183)
Less: current portion	0	0
Total long-term debt	3,332,188	3,469,137
8.625% senior notes due 2017
Debt Instrument [Line Items]
Deferred loan costs, net	(5,500)
7.0% unsecured senior notes due 2021
Debt Instrument [Line Items]
Unsecured senior notes	600,000	600,000
6.5% unsecured senior notes due 2022
Debt Instrument [Line Items]
Unsecured senior notes	600,000	600,000
5.5% unsecured senior notes due 2022
Debt Instrument [Line Items]
Unsecured senior notes	600,000	600,000
5.5% unsecured senior notes due 2023
Debt Instrument [Line Items]
Unsecured senior notes	$ 1,550,000	$ 1,550,000

Debt (Narrative) (Detail)

Debt (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Disclosure [Line Items]
Line of credit maturity date	May 9, 2019
Aggregate lender commitments	$ 2,500,000
Aggregate maximum borrowing base	3,250,000
Unused lender commitments	$ 2,500,000
Line of credit interest rate	3.50%
Debt Related Commitment Fees	$ 7,000	$ 7,700	$ 8,300
Loss on extinguishment of debt	0	(4,316)	$ (28,616)
Unamortized Debt Issuance Expense	$ 42,885	$ 48,183
Minimum [Member]
Debt Disclosure [Line Items]
Commitment fees on unused portion of available commitment	0.30%
Maximum [Member]
Debt Disclosure [Line Items]
Commitment fees on unused portion of available commitment	0.375%
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%
8.625% senior notes due 2017
Debt Disclosure [Line Items]
Interest rate	8.625%
Debt Instrument Maturity Year	2,017
Debt Instrument, Repurchased Face Amount	$ 225,600
Percentage Of Notes Tendered	75.20%
Price Of Tender And Consent	106.922%
Price Of Remaining Notes Tendered	106.516%
Premium Paid For Tender Offer	$ 20,400
Unamortized Debt Issuance Expense	5,500
Debt Instrument, Unamortized Discount	2,700
5.5% unsecured senior notes due 2023
Debt Disclosure [Line Items]
Debt instrument amount issued	$ 850,000
Interest rate	5.50%
Debt instrument percent of par value issued	103.75%
Debt Instrument Maturity Year	2,023
Resulting Yield	4.884%
Proceeds from Debt, Net of Issuance Costs	$ 867,800

Debt (Principal Maturities Of D

Debt (Principal Maturities Of Debt) (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Disclosure Debt Principal Maturities Of Debt [Abstract]
2,016	$ 0
2,017	0
2,018	0
2,019	0
2,020	0
Thereafter	3,350,000
Total	$ 3,350,000

Debt (Summary Of Interest Expen

Debt (Summary Of Interest Expense) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Debt Summary Of Interest Expense [Abstract]
Cash payments for interest	$ (211,443)	$ (211,342)	$ (200,961)
Amortization of original issue discount (premium)	(2,747)	(2,599)	(1,248)
Amortization of deferred loan origination costs	9,971	10,937	13,172
Accretion expense	1,795	0	0
Net changes in accruals	(165)	(737)	5,696
Interest costs incurred	220,297	218,943	218,581
Less: capitalized interest	(4,913)	(2,282)	0
Total interest expense	$ 215,384	$ 216,661	$ 218,581

Commitments And Contingencies70

Commitments And Contingencies (Narrative) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commitments [Line Items]
Annual officers' salaries	$ 8.5
Operating leases, lease payments	8	$ 7.2	$ 5.7
Accrued Exposure	$ 13.4	$ 12.3

Commitments And Contingencies71

Commitments And Contingencies (Future Commitments) (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Disclosure Commitments And Contingencies Future Commitments [Abstract]
2,016	$ 51,710
2,017	21,256
2,018	21,148
2,019	13,196
2,020	7,335
Thereafter	45,451
Total	$ 160,096

Commitments And Contingencies72

Commitments And Contingencies (Future Minimum Lease Commitments Under Non-Cancellable Operating Leases) (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Disclosure Commitments And Contingencies Future Minimum Lease Commitments Under Non Cancellable Operating Leases [Abstract]
2,016	$ 7,941
2,017	7,877
2,018	7,087
2,019	5,651
2,020	4,738
Thereafter	5,091
Total	$ 38,385

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Income Taxes Narrative [Abstract]
Income taxes receivable, current	$ 37,300	$ 32,900
Income taxes payable, current	1,000	1,100
Change in estimated effective statutory state income tax	$ (9,026)	$ (7,945)	$ (21,876)
State Tax Rate Reduction	9.30%
Income Tax Rate Reduction	4.80%

Income Taxes (Company's Income

Income Taxes (Company's Income Tax Provision (Benefit)) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Income Taxes Companys Income Tax Provision Benefit [Abstract]
Income from continuing operations	$ 31,371	$ 317,785	$ 118,237
Income from discontinued operations	0	0	7,518
Excess tax benefits related to stock-based compensation	(2,150)	(16,480)	(6,147)
Income Tax Expense Benefit Net Of Excess Tax Benefits, Total	$ 29,221	$ 301,305	$ 119,608

Income Taxes (Income Tax Provis

Income Taxes (Income Tax Provision (Benefit) Attributable To Income (Loss) From Continuing Operations) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Income Taxes Income Tax Provision Benefit Attributable To Income Loss From Continuing Operations [Abstract]
U.S. federal	$ 127	$ 16,621	$ 12,504
U.S. state and local	1,622	4,997	3,306
Total current income tax provision	1,749	21,618	15,810
U.S. federal	40,364	278,615	119,985
U.S. state and local	(10,742)	17,552	(17,558)
Total deferred income tax provision	29,622	296,167	102,427
Total income tax provision attributable to income from continuing operations	$ 31,371	$ 317,785	$ 118,237

Income Taxes (Reconciliation Be

Income Taxes (Reconciliation Between The Income Tax Expense (Benefit) And The Reported Amounts Of Income Tax Expense) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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	$ 34,045	$ 299,586	$ 125,006
State income taxes (net of federal tax effect)	3,071	22,826	12,505
Revisions of previous estimates	(631)	738	1,400
Change in estimated effective statutory state income tax	(9,026)	(7,945)	(21,876)
Nondeductible expense & other	3,912	2,580	1,202
Total income tax provision attributable to income from continuing operations	$ 31,371	$ 317,785	$ 118,237
Effective tax rate	32.30%	37.10%	33.10%

Income Taxes (Company's Incom77

Income Taxes (Company's Income Tax Provision Attributable To Income From Discontinued Operations) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Income Taxes Companys Income Tax Provision Attributable To Income From Discontinued Operations [Abstract]
U.S. federal, current			$ 144
U.S. state and local, current			25
Total current income tax provision			169
U.S. federal, deferred			6,397
U.S. state and local, deferred			952
Total deferred income tax provision			7,349
Total income tax provision attributable to income from discontinued operations	$ 0	$ 0	$ 7,518

Income Taxes (Deferred Tax Asse

Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Components of Deferred Tax Assets and Liabilities [Abstract]
Stock Based Compensation	$ 36,738	$ 24,810
Asset retirement obligation	44,573	44,802
Other	29,574	28,925
Total Deferred tax assets	(110,885)	(98,537)
Oil and Gas Properties deduction of intangible drilling cost due to tax purpose	(1,420,275)	(1,401,313)
Intangible Assets - Operating rights	(9,548)	(10,148)
Derivative instruments	(304,550)	(281,303)
Other	(6,885)	(6,524)
Deferred Tax Liabilities, Gross	(1,741,258)	(1,699,288)
Net deferred tax liabilities	$ (1,630,373)	$ (1,600,751)

Major Customers and Derivativ79

Major Customers and Derivative Counterparties (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Holly Frontier Refining and Marketing LLC [Member]
Revenue, Major Customer [Line Items]
Entity Wide Receivables Major Customer	$ 31.7
Holly Frontier Refining and Marketing LLC [Member] | Revenue [Member]
Revenue, Major Customer [Line Items]
Major Customer Percentage	25.00%	17.00%	30.00%
Enterprise Crude Oil LLC [Member]
Revenue, Major Customer [Line Items]
Entity Wide Receivables Major Customer	$ 10.4
Enterprise Crude Oil LLC [Member] | Revenue [Member]
Revenue, Major Customer [Line Items]
Major Customer Percentage	12.00%	12.00%	13.00%
Western Refining Company LP [Member]
Revenue, Major Customer [Line Items]
Entity Wide Receivables Major Customer	$ 3.9
Western Refining Company LP [Member] | Revenue [Member]
Revenue, Major Customer [Line Items]
Major Customer Percentage	5.00%	12.00%	1.00%
Plains Marketing and Transportation Inc [Member]
Revenue, Major Customer [Line Items]
Entity Wide Receivables Major Customer	$ 11.6
Plains Marketing and Transportation Inc [Member] | Revenue [Member]
Revenue, Major Customer [Line Items]
Major Customer Percentage	11.00%	6.00%	4.00%

Derivative Counterparties (Deta

Derivative Counterparties (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Derivative Counterparties Fair Value [Line Items]
Net financial assets (liabilities)	$ 819,536	$ 752,700
JP Morgan Chase Bank [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	100,500
Wells Fargo Bank NA [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	90,300
Barclays Bank PLC [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	121,800
KeyBank National Association [Member]
Derivative Counterparties Fair Value [Line Items]
Credit Risk Derivative Assets at Fair Value	$ 74,700

Related Party Transactions (Sch

Related Party Transactions (Schedule Of Related Party Transactions) (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Ownership interest in partnership		3.50%
Partnership (Director Ownership Interest) [Member]
Related Party Transaction [Line Items]
Amounts paid	[1]	$ 5,745,000	$ 15,181,000	$ 7,255,000
Director And Certain Officers [Member]
Related Party Transaction [Line Items]
Amounts paid	[2]	593,000	383,000	43,000
Payments for Notes to Directors and Officers				1,300,000
Related party receivable from an officer (or affiliated entities)			76,000
Payments From Officers	[3]	237,000	169,000	84,000
Former President And Chief Operating Officer [Member]
Related Party Transaction [Line Items]
Amounts paid under consulting agreement with Steven L. Beal	[4]	$ 0	$ 0	865,000
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]	Amounts include revenue interests, overriding royalty interests and net profits interests in properties owned by the Company made to a director and certain officers (or affiliated entities). Amounts also include payments for an acreage acquisition and lease bonuses to an affiliated entity of an office r.
[3]	Amounts include p ayments to the Company as a result of activity on oil and natural gas properties in which a director and certain officers (or affiliated entities) have an interest.
[4]	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. Be al 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.

Net Income Per Share (Reconcili

Net Income Per Share (Reconciliation Of Earnings Attributable To Common Shares Basic And Diluted) (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Income as reported	$ 65,900	$ 538,175	$ 251,003
Participating basic earnings	(635)	(5,961)	(2,742)
Basic income attributable to common stockholders	65,265	532,214	248,261
Reallocation of participating earnings	2	16	4
Diluted income attributable to common stockholders	$ 65,267	$ 532,230	$ 248,265
Basic	$ 0.54	$ 4.89	$ 2.39
Diluted	$ 0.54	$ 4.88	$ 2.39
Segment, Continuing Operations [Member]
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Income as reported			$ 238,922
Participating basic earnings			(2,610)
Basic income attributable to common stockholders			236,312
Reallocation of participating earnings			4
Diluted income attributable to common stockholders			$ 236,316
Basic			$ 2.28
Diluted			$ 2.28
Segment, Discontinued Operations [Member]
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Income as reported			$ 12,081
Participating basic earnings			(132)
Basic income attributable to common stockholders			11,949
Reallocation of participating earnings			0
Diluted income attributable to common stockholders			$ 11,949
Basic			$ 0.11
Diluted			$ 0.11

Net Income Per Share (Reconci83

Net Income Per Share (Reconciliation Of The Weighted Average Common Shares Outstanding) (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation Of Basic Weighted Average Common Shares Outstanding To Diluted Weighted Average Common Shares Outstanding [Line Items]
Basic	119,926	108,844	103,744
Diluted	120,373	109,132	103,913
Stock Options [Member]
Reconciliation Of Basic Weighted Average Common Shares Outstanding To Diluted Weighted Average Common Shares Outstanding [Line Items]
Dilutive shares	25	83	165
Performance Unit [Member]
Reconciliation Of Basic Weighted Average Common Shares Outstanding To Diluted Weighted Average Common Shares Outstanding [Line Items]
Dilutive shares	422	205	4

Net Income Per Share (Summary O

Net Income Per Share (Summary Of The Common Stock Options And Restricted Stock) (Detail) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Performance Unit [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive common shares	0	0	83

Other Current Liabilities (Sche

Other Current Liabilities (Schedule Of Other Current Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Other Liabilities Disclosure [Abstract]
Accrued production costs	$ 70,876	$ 70,786
Payroll related matters	29,411	34,349
Accrued interest	68,925	69,264
Asset retirement obligations	8,626	9,146
Other	7,072	11,763
Other current liabilities	$ 184,910	$ 195,308

Subsidiary Guarantors (Condense

Subsidiary Guarantors (Condensed Consolidating Balance Sheet) (Detail) - USD ($)	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ASSETS
Accounts receivable - related parties	$ 0	$ 0
Other current assets	1,314,550,000	1,188,396,000
Oil and natural gas properties, net	10,798,497,000	10,076,878,000
Property and equipment, net	178,450,000	129,136,000
Investment in subsidiaries	0	0
Other long-term assets	350,379,000	357,370,000
Total assets	12,641,876,000	11,751,780,000
LIABILITIES AND EQUITY
Accounts payable - related parties	0	0
Other current liabilities	596,420,000	1,264,627,000
Long-term debt	3,332,188,000	3,469,137,000
Other long-term liabilities	1,770,717,000	1,737,228,000
Equity	6,942,551,000	5,280,788,000	$ 3,757,949,000	$ 3,466,196,000
Total liabilities and stockholders' equity	12,641,876,000	11,751,780,000
Consolidation Eliminations [Member]
ASSETS
Accounts receivable - related parties	(9,664,396,000)	(7,872,694,000)
Other current assets	0	0
Oil and natural gas properties, net	0	0
Property and equipment, net	0	0
Investment in subsidiaries	(3,698,485,000)	(4,085,045,000)
Other long-term assets	0	0
Total assets	(13,362,881,000)	(11,957,739,000)
LIABILITIES AND EQUITY
Accounts payable - related parties	(9,664,396,000)	(7,872,694,000)
Other current liabilities	0	0
Long-term debt	0	0
Other long-term liabilities	0	0
Equity	(3,698,485,000)	(4,085,045,000)
Total liabilities and stockholders' equity	(13,362,881,000)	(11,957,739,000)
Parent Company [Member]
ASSETS
Accounts receivable - related parties	8,502,099,000	6,670,744,000
Other current assets	753,716,000	569,545,000
Oil and natural gas properties, net	0	0
Property and equipment, net	0	0
Investment in subsidiaries	3,698,485,000	4,085,045,000
Other long-term assets	182,623,000	282,609,000
Total assets	13,136,923,000	11,607,943,000
LIABILITIES AND EQUITY
Accounts payable - related parties	1,162,297,000	1,201,950,000
Other current liabilities	69,514,000	55,318,000
Long-term debt	3,332,188,000	3,469,137,000
Other long-term liabilities	1,630,373,000	1,600,750,000
Equity	6,942,551,000	5,280,788,000
Total liabilities and stockholders' equity	13,136,923,000	11,607,943,000
Guarantor Subsidiaries [Member]
ASSETS
Accounts receivable - related parties	1,162,297,000	1,201,950,000
Other current assets	560,834,000	618,851,000
Oil and natural gas properties, net	10,798,497,000	10,076,878,000
Property and equipment, net	178,450,000	129,136,000
Investment in subsidiaries	0	0
Other long-term assets	167,756,000	74,761,000
Total assets	12,867,834,000	12,101,576,000
LIABILITIES AND EQUITY
Accounts payable - related parties	8,502,099,000	6,670,744,000
Other current liabilities	526,906,000	1,209,309,000
Long-term debt	0	0
Other long-term liabilities	140,344,000	136,478,000
Equity	3,698,485,000	4,085,045,000
Total liabilities and stockholders' equity	$ 12,867,834,000	$ 12,101,576,000

Subsidiary Guarantors (Conden87

Subsidiary Guarantors (Condensed Consolidating Statement Of Operations) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements Captions [Line Items]
Total operating revenues	$ 1,803,573,000	$ 2,660,147,000	$ 2,319,919,000
Total operating costs and expenses	1,422,570,000	1,570,402,000	1,702,482,000
Income (loss) from operations	381,003,000	1,089,745,000	617,437,000
Interest expense	(215,384,000)	(216,661,000)	(218,581,000)
Loss on extinguishment of debt	0	(4,316,000)	(28,616,000)
Other, net	(68,348,000)	(12,808,000)	(13,081,000)
Income from continuing operations before income taxes	97,271,000	855,960,000	357,159,000
Income tax expense	(31,371,000)	(317,785,000)	(118,237,000)
Income from continuing operations	65,900,000	538,175,000	238,922,000
Income from discontinued operations, net of tax			12,081,000
Net income	65,900,000	538,175,000	251,003,000
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 operations	0	0	0
Interest expense	0	0	0
Loss on extinguishment of debt		0	0
Other, net	386,560,000	(188,304,000)	(749,823,000)
Income from continuing operations before income taxes	386,560,000	(188,304,000)	(749,823,000)
Income tax expense	0	0	0
Income from continuing operations			(749,823,000)
Income from discontinued operations, net of tax			0
Net income	386,560,000	(188,304,000)	(749,823,000)
Parent Company [Member]
Condensed Financial Statements Captions [Line Items]
Total operating revenues	0	0	0
Total operating costs and expenses	(697,247,000)	(888,632,000)	125,924,000
Income (loss) from operations	697,247,000	888,632,000	(125,924,000)
Interest expense	(213,416,000)	(216,661,000)	(218,581,000)
Loss on extinguishment of debt		(4,316,000)	(28,616,000)
Other, net	(386,560,000)	188,305,000	749,878,000
Income from continuing operations before income taxes	97,271,000	855,960,000	376,757,000
Income tax expense	(31,371,000)	(317,785,000)	(118,237,000)
Income from continuing operations			258,520,000
Income from discontinued operations, net of tax			(7,517,000)
Net income	65,900,000	538,175,000	251,003,000
Guarantor Subsidiaries [Member]
Condensed Financial Statements Captions [Line Items]
Total operating revenues	1,803,573,000	2,660,147,000	2,319,919,000
Total operating costs and expenses	2,119,817,000	2,459,034,000	1,576,558,000
Income (loss) from operations	(316,244,000)	201,113,000	743,361,000
Interest expense	(1,968,000)	0	0
Loss on extinguishment of debt		0	0
Other, net	(68,348,000)	(12,809,000)	(13,136,000)
Income from continuing operations before income taxes	(386,560,000)	188,304,000	730,225,000
Income tax expense	0	0	0
Income from continuing operations			730,225,000
Income from discontinued operations, net of tax			19,598,000
Net income	$ (386,560,000)	$ 188,304,000	$ 749,823,000

Subsidiary Guarantors (Conden88

Subsidiary Guarantors (Condensed Consolidating Statement Of Cash Flows) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements Captions [Line Items]
Net cash flows provided by (used in) operating activities	$ 897,505,000	$ 1,673,787,000	$ 1,362,020,000
Net cash flows provided by (used in) investing activities	(1,969,725,000)	(2,545,996,000)	(1,896,794,000)
Net cash flows provided by (used in) financing activities	1,300,749,000	872,209,000	531,915,000
Net increase (decrease) in cash and cash equivalents	228,529,000	0	(2,859,000)
Cash and cash equivalents at beginning of period	21,000	21,000	2,880,000
Cash and cash equivalents at end of period	228,550,000	21,000	21,000
Consolidation Eliminations [Member]
Condensed Financial Statements Captions [Line Items]
Net cash flows provided by (used in) operating activities	0	0	0
Net cash flows provided by (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	0
Cash and cash equivalents at end of period	0	0	0
Parent Company [Member]
Condensed Financial Statements Captions [Line Items]
Net cash flows provided by (used in) operating activities	(2,026,206,000)	(888,369,000)	(487,131,000)
Net cash flows provided by (used in) investing activities	632,916,000	71,983,000	(32,341,000)
Net cash flows provided by (used in) financing activities	1,393,290,000	816,386,000	519,472,000
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	2,923,711,000	2,562,156,000	1,849,151,000
Net cash flows provided by (used in) investing activities	(2,602,641,000)	(2,617,979,000)	(1,864,453,000)
Net cash flows provided by (used in) financing activities	(92,541,000)	55,823,000	12,443,000
Net increase (decrease) in cash and cash equivalents	228,529,000	0	(2,859,000)
Cash and cash equivalents at beginning of period	21,000	21,000	2,880,000
Cash and cash equivalents at end of period	$ 228,550,000	$ 21,000	$ 21,000

Subsequent Events (Narrative) (

Subsequent Events (Narrative) (Detail) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2013
Subsequent Event [Line Items]
Acquisiton Agreement date	Jan. 1, 2016
Number of common stock issued	2.2
Payments To Acquire Oil And Gas Property	$ 150
Future Carry Amount	40
Proceeds From Sale Of Oil And Gas Property And Equipment	$ 290
Disposal Date	Jan. 1, 2016	Dec. 15, 2012

Subsequent Events (New Commodit

Subsequent Events (New Commodity Derivative Contracts) (Detail) - Subsequent Event [Member]		3 Months Ended				12 Months Ended
		Dec. 31, 2016bbl$ / bbl	Sep. 30, 2016bbl$ / bbl	Jun. 30, 2016bbl$ / bbl	Mar. 31, 2016bbl$ / bbl	Dec. 31, 2016bbl$ / bbl
Oil Swaps [Member]
Subsequent Event [Line Items]
Volume (Bbl/MMBtu) - Year One | bbl	[1]	750,000	750,000	180,000	180,000	1,860,000
Price per Bbl/MMBtu - Year One | $ / bbl	[1]	43.63	43.63	42.55	42.55	43.42
Oil Basis Swaps [Member]
Subsequent Event [Line Items]
Volume (Bbl/MMBtu) - Current Year | bbl	[2]	0	0	182,000	120,000	302,000
Price per Bbl/MMBtu - Current Year | $ / bbl	[2]	0	0	(0.25)	(0.25)	(0.25)
Volume (Bbl/MMBtu) - Year One | bbl	[2]	2,024,000	2,024,000	242,000	360,000	4,650,000
Price per Bbl/MMBtu - Year One | $ / bbl	[2]	(0.38)	(0.38)	(0.38)	(0.41)	(0.38)
[1]	The index prices for the oil price swaps are based on the NYMEX – WTI monthly average futures price.
[2]	The basis differential price is between Midland – WTI and Cushing – WTI.