Bill Barrett (BBG) 10-Q 5 Nov 15 2015 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2015	Oct. 23, 2015
Document Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q3
Trading Symbol	BBG
Entity Registrant Name	BILL BARRETT CORPORATION
Entity Central Index Key	1,172,139
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		49,959,996

CONSOLIDATED BALANCE SHEETS (UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 92,836	$ 165,904
Short-term investments	19,992	0
Accounts receivable, net of allowance for doubtful accounts	44,070	112,209
Derivative assets	109,847	145,226
Prepayments and other current assets	3,395	2,766
Total current assets	270,140	426,105
Property and equipment - at cost, successful efforts method for oil and gas properties:
Proved oil and gas properties	1,942,076	2,009,292
Unproved oil and gas properties, excluded from amortization	95,213	148,834
Oil and gas properties held for sale, net of amortization and impairment	64,882	9,234
Furniture, equipment and other	29,496	39,963
Property, plant and equipment, gross	2,131,667	2,207,323
Accumulated depreciation, depletion, amortization and impairment	(892,720)	(454,202)
Total property and equipment, net	1,238,947	1,753,121
Deferred income taxes	42,137	0
Derivative assets	32,209	49,750
Deferred financing costs and other noncurrent assets	12,827	15,508
Total	1,596,260	2,244,484
Current liabilities:
Accounts payable and accrued liabilities	111,309	126,252
Amounts payable to oil and gas property owners	18,337	19,187
Production taxes payable	27,416	38,060
Deferred income taxes	42,137	55,418
Current portion of long-term debt	1,015	25,770
Total current liabilities	200,214	264,687
Long-term debt	802,894	803,222
Asset retirement obligations	14,699	21,592
Liabilities associated with assets held for sale	7,641	146
Deferred income taxes	0	122,350
Derivatives and other noncurrent liabilities	3,046	2,999
Stockholders' equity:
Common stock, $0.001 par value; authorized 150,000,000 shares; 49,961,616 and 49,526,637 shares issued and outstanding at September 30, 2015 and December 31, 2014, respectively, with 1,604,739 and 1,407,141 shares subject to restrictions, respectively	48	48
Additional paid-in capital	918,523	913,619
Retained earnings (Accumulated deficit)	(350,805)	115,821
Treasury stock, at cost: zero shares at September 30, 2015 and December 31, 2014, respectively	0	0
Total stockholders' equity	567,766	1,029,488
Total liabilities and stockholders' equity	$ 1,596,260	$ 2,244,484

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	49,961,616	49,526,637
Common stock, shares outstanding (in shares)	49,961,616	49,526,637
Common stock, shares subject to restrictions (in shares)	1,604,739	1,407,141
Treasury stock, shares (in shares)	0	0

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating and Other Revenues:
Oil, gas and NGL production	$ 48,799	$ 134,342	$ 158,667	$ 397,731
Other	880	921	2,664	7,658
Total operating and other revenues	49,679	135,263	161,331	405,389
Operating Expenses:
Lease operating expense	9,638	16,284	34,834	48,367
Gathering, transportation and processing expense	684	10,784	2,559	34,238
Production tax expense	3,670	10,495	10,020	27,770
Exploration expense	20	23	145	442
Impairment, dry hole costs and abandonment expense	572,651	29,109	574,996	32,613
(Gain) Loss on divestitures	(77)	99,466	(759)	96,896
Depreciation, depletion and amortization	54,738	69,024	159,666	189,426
Unused commitments	4,388	0	13,163	0
General and administrative expense	11,025	11,111	39,026	41,039
Total operating expenses	656,737	246,296	833,650	470,791
Operating Income (Loss)	(607,058)	(111,033)	(672,319)	(65,402)
Other Income and Expense:
Interest and other income	100	264	519	991
Interest expense	(15,754)	(18,033)	(49,574)	(53,285)
Commodity derivative gain (loss)	69,133	72,299	75,914	369
Gain (Loss) on extinguishment of debt	0	0	1,749	0
Total other income and expense	53,479	54,530	28,608	(51,925)
Income (Loss) before Income Taxes	(553,579)	(56,503)	(643,711)	(117,327)
(Provision for) Benefit from Income Taxes	143,265	21,854	177,085	43,343
Net Income (Loss)	$ (410,314)	$ (34,649)	$ (466,626)	$ (73,984)
Net Income (Loss) Per Common Share, Basic (in dollars per share)	$ (8.49)	$ (0.72)	$ (9.67)	$ (1.54)
Net Income (Loss) Per Common Share, Diluted (in dollars per share)	$ (8.49)	$ (0.72)	$ (9.67)	$ (1.54)
Weighted Average Common Shares Outstanding, Basic (in shares)	48,339,639	48,060,086	48,279,763	47,982,992
Weighted Average Common Shares Outstanding, Diluted (in shares)	48,339,639	48,060,086	48,279,763	47,982,992

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ (410,314)	$ (34,649)	$ (466,626)	$ (73,984)	$ 15,081
Other Comprehensive Income (Loss), net of tax:
Effect of derivative financial instruments	0	(219)	0	(555)	$ (669)
Other comprehensive income (loss)	0	(219)	0	(555)
Comprehensive Income (Loss)	$ (410,314)	$ (34,868)	$ (466,626)	$ (74,539)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Operating Activities:
Net Income (Loss)	$ (466,626)	$ (73,984)
Adjustments to reconcile to net cash provided by operations:
Depreciation, depletion and amortization	159,666	189,426
Deferred income tax benefit	(176,797)	(43,604)
Impairment, dry hole costs and abandonment expense	574,996	32,613
Total commodity derivative (gain) loss	(75,914)	(369)
Gain (Loss) on settlements of commodity derivatives	128,834	(21,580)
Stock compensation and other non-cash charges	7,281	9,651
Amortization of debt discounts and deferred financing costs	3,983	3,200
(Gain) Loss on extinguishment of debt	(1,749)	0
(Gain) Loss on sale of properties	(759)	96,896
Change in operating assets and liabilities:
Accounts receivable	20,394	9,025
Prepayments and other assets	(261)	914
Accounts payable, accrued and other liabilities	4,347	20,723
Amounts payable to oil and gas property owners	(850)	1,936
Production taxes payable	(10,644)	6,455
Net cash provided by (used in) operating activities	165,901	231,302
Investing Activities:
Additions to oil and gas properties, including acquisitions	(256,059)	(425,978)
Additions of furniture, equipment and other	(1,036)	(2,110)
Proceeds from sale of properties and other investing activities	66,617	557,747
Cash paid for short-term investments	(114,883)	0
Proceeds from the sale of short-term investments	95,000	0
Net cash provided by (used in) investing activities	(210,361)	129,659
Financing Activities:
Proceeds from debt	0	165,000
Principal payments on debt	(25,083)	(283,442)
Proceeds from stock option exercises	0	126
Deferred financing costs and other	(3,525)	(2,462)
Net cash provided by (used in) financing activities	(28,608)	(120,778)
Increase (Decrease) in Cash and Cash Equivalents	(73,068)	240,183
Beginning Cash and Cash Equivalents	165,904	54,595
Ending Cash and Cash Equivalents	$ 92,836	$ 294,778

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)	Treasury Stock	Accumulated Other Comprehensive Income
Balance at Dec. 31, 2013	$ 1,005,718	$ 48	$ 904,261	$ 100,740	$ 0	$ 669
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of options, restricted stock activity and shares exchanged for exercise and tax withholding	(2,558)		126		(2,684)
Stock-based compensation	11,916		11,916
Retirement of treasury stock	0		(2,684)		2,684
Net income (loss)	15,081			15,081
Effect of derivative financial instruments, net of taxes	(669)					(669)
Balance at Dec. 31, 2014	1,029,488	48	913,619	115,821	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of options, restricted stock activity and shares exchanged for exercise and tax withholding	(1,100)				(1,100)
Stock-based compensation	7,600		7,600
Retirement of treasury stock	0		(1,100)		1,100
Settlement of convertible notes	(1,596)	0	(1,596)	0	0	$ 0
Net income (loss)	(466,626)			(466,626)
Effect of derivative financial instruments, net of taxes	0
Balance at Sep. 30, 2015	$ 567,766	$ 48	$ 918,523	$ (350,805)	$ 0

CONSOLIDATED STATEMENTS OF STO8

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Statement of Stockholders' Equity [Abstract]
Effect of derivative financial instruments, taxes	$ 0	$ 410

Organization

Organization	9 Months Ended
	Sep. 30, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Bill Barrett Corporation, a Delaware corporation, together with its wholly-owned subsidiaries (collectively, the "Company"), is an independent oil and gas company engaged in the exploration, development and production of crude oil, natural gas and natural gas liquids ("NGLs"). Since its inception in January 2002, the Company has conducted its activities principally in the Rocky Mountain region of the United States.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation. The accompanying Unaudited Consolidated Financial Statements include the accounts of the Company. These statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"). All intercompany accounts and transactions have been eliminated in consolidation. In the opinion of management, the accompanying financial statements include all adjustments (consisting of normal recurring accruals and adjustments) necessary to present fairly, in all material respects, the Company's interim results. However, operating results for the periods presented are not necessarily indicative of the results that may be expected for the full year. The Company's Annual Report on Form 10-K includes certain definitions and a summary of significant accounting policies and should be read in conjunction with this Quarterly Report on Form 10-Q. Except as disclosed herein, there have been no material changes to the information disclosed in the notes to the consolidated financial statements included in the Company's 2014 Annual Report on Form 10-K. Use of Estimates. In the course of preparing the Company's financial statements in accordance with GAAP, management makes various assumptions, judgments and estimates to determine the reported amount of assets, liabilities, revenues and expenses and in the disclosure of commitments and contingencies. Changes in these assumptions, judgments and estimates will occur as a result of the passage of time and the occurrence of future events and, accordingly, actual results could differ from amounts initially established. Areas requiring the use of assumptions, judgments and estimates relate to volumes of oil, natural gas and NGL reserves used in calculating depreciation, depletion and amortization ("DD&A"), the amount of expected future cash flows used in determining possible impairments of proved oil and gas properties and the amount of future capital costs used in these calculations. Assumptions, judgments and estimates also are required in determining asset retirement obligations, the timing of dry hole costs, impairments of unproved oil and gas properties, valuing deferred tax assets and estimating fair values of derivative instruments and stock-based compensation awards. Short-term Investments. Short-term investments have maturities of more than three months and less than one year. The Company's held-to-maturity securities have a carrying value of $20.0 million , which approximates fair value, as of September 30, 2015 , and all have maturity dates of less than one year. Accounts Receivable. Accounts receivable is comprised of the following: As of September 30, 2015 As of December 31, 2014 (in thousands) Accrued oil, gas and NGL sales $ 33,018 $ 35,099 Due from joint interest owners 9,333 27,937 Other (1) 1,733 49,187 Allowance for doubtful accounts (14 ) (14 ) Total accounts receivable $ 44,070 $ 112,209 (1) Other as of December 31, 2014 includes a receivable of $47.6 million (including $4.7 million due to another industry partner) related to a settlement agreement with the Department of Interior resulting in the cancellation of certain Cottonwood Gulch natural gas leases during the three months ended December 31, 2014. Oil and Gas Properties. The Company's oil, gas and NGL exploration and production activities are accounted for using the successful efforts method. Under this method, all property acquisition costs and costs of exploratory and development wells are capitalized when incurred, pending determination of whether the well has found proved reserves. If an exploratory well does not find proved reserves, the costs of drilling the well are charged to expense and remain within cash flows from investing activities in the Unaudited Consolidated Statements of Cash Flows. If an exploratory well does find proved reserves, the costs remain capitalized and are included within additions to oil and gas properties and remain within cash flows from investing activities in the Unaudited Consolidated Statements of Cash Flows. The costs of development wells are capitalized whether proved reserves are added or not. Oil and gas lease acquisition costs are also capitalized. Upon sale or retirement of depreciable or depletable property, the cost and related accumulated DD&A are eliminated from the accounts and the resulting gain or loss is recognized. Other exploration costs, including certain geological and geophysical expenses and delay rentals for oil and gas leases, are charged to expense as incurred. The sale of a partial interest in a proved property is accounted for as a cost recovery and no gain or loss is recognized as long as this treatment does not significantly affect the unit-of-production amortization rate. Maintenance and repairs are charged to expense, and renewals and betterments are capitalized to the appropriate property and equipment accounts. Unproved oil and gas property costs are transferred to proved oil and gas properties if the properties are subsequently determined to be productive or are assigned proved reserves. Proceeds from sales of partial interests in unproved leases are accounted for as a recovery of cost without recognizing any gain until all costs are recovered. Unproved oil and gas properties are assessed periodically for impairment based on remaining lease terms, drilling results, reservoir performance, commodity price outlooks, future plans to develop acreage and other relevant matters. Materials and supplies consist primarily of tubular goods and well equipment to be used in future drilling operations or repair operations and are carried at the lower of cost or market value, on a first-in, first-out basis. The following table sets forth the net capitalized costs and associated accumulated DD&A and non-cash impairments relating to the Company's oil, natural gas and NGL producing activities: As of September 30, 2015 As of December 31, 2014 (in thousands) Proved properties $ 321,201 $ 390,482 Wells and related equipment and facilities 1,536,447 1,537,370 Support equipment and facilities 74,438 68,371 Materials and supplies 9,990 13,069 Total proved oil and gas properties $ 1,942,076 $ 2,009,292 Unproved properties 28,514 78,898 Wells and facilities in progress 66,699 69,936 Total unproved oil and gas properties, excluded from amortization $ 95,213 $ 148,834 Assets held for sale 64,882 9,234 Accumulated depreciation, depletion, amortization and impairment (875,852 ) (427,954 ) Total oil and gas properties, net $ 1,226,319 $ 1,739,406 The Company reviews proved oil and gas properties on a field-by-field basis for impairment on a quarterly basis or whenever events and circumstances indicate that a decline in the recoverability of their carrying value may have occurred. The Company estimates the expected undiscounted future net cash flows of its oil and gas properties based on the Company's best estimate of development plans, future production, commodity pricing, gathering and transportation deductions, production tax rates, lease operating expenses and future development costs. The Company compares such undiscounted future net cash flows to the carrying amount of the oil and gas properties to determine if the carrying amount is recoverable. If the undiscounted future net cash flows exceed the carrying amount of the proved oil and gas properties, no impairment is taken. If the carrying value of a property exceeds the undiscounted future net cash flows, the Company will impair the carrying value to fair value based on an analysis of quantitative and qualitative factors existing as of the balance sheet date. The Company does not believe that the undiscounted future net cash flows analysis of its proved property represents the applicable market value. The factors used to determine fair value include, but are not limited to, recent sales prices of comparable properties, indications from marketing activities, the present value of future revenues, net of estimated operating and development costs using estimates of reserves, future commodity pricing, future production estimates, anticipated capital expenditures and various discount rates commensurate with the risk and current market conditions associated with realizing the projected cash flows. The Company recognized non-cash impairment, dry hole costs and abandonment expense in the Unaudited Consolidated Statements of Operations, as follows: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands) Non-cash impairment of proved oil and gas properties $ 556,291 (1) $ 11,493 (2) $ 556,563 (1) $ 12,531 (2)(3) Non-cash impairment of unproved oil and gas properties 15,572 (1) 15,250 (2) 15,803 (1) 15,250 (2) Non-cash impairment of inventory — — — 340 Dry hole costs 14 3 (29 ) 96 Abandonment expense and lease expirations 774 2,363 2,659 4,396 Total non-cash impairment, dry hole costs and abandonment expense $ 572,651 $ 29,109 $ 574,996 $ 32,613 (1) Due to the continued decline in oil prices, the Company recognized a non-cash impairment charge associated with the Company's Uinta Oil Program proved and unproved oil and gas properties for the three and nine months ended September 30, 2015. (2) As a result of the sale or exchange of the majority of the Company's Powder River Basin assets ("Powder River Oil Divestiture") and results of drilling and completion activity in the Paradox Basin during the three months ended September 30, 2014, the remaining carrying values of Powder River Oil and Paradox Basin assets were analyzed relative to their estimated fair market values. As a result, the Company recognized proved and unproved property impairments of $11.5 million and $15.3 million , respectively. (3) The amount shown reflects $1.0 million of proved impairment expense that was incurred during the nine months ended September 30, 2014 related to the sale of the Company's West Tavaputs natural gas assets in the Uinta Basin ("West Tavaputs Divestiture") based upon a true up of previously estimated fair value relative to carrying value. These assets were sold in December 2013. The provision for DD&A of oil and gas properties is calculated on a field-by-field basis using the unit-of-production method. Natural gas and NGLs are converted to an oil equivalent, Boe, at the standard rate of six Mcf to one Boe and forty-two gallons to one Boe, respectively. Estimated future dismantlement, restoration and abandonment costs are taken into consideration by this calculation. Accounts Payable and Accrued Liabilities. Accounts payable and accrued liabilities are comprised of the following: As of September 30, 2015 As of December 31, 2014 (in thousands) Accrued drilling, completion and facility costs $ 49,664 $ 68,124 Accrued lease operating, gathering, transportation and processing expenses 10,718 12,526 Accrued general and administrative expenses 8,695 8,482 Accrued interest payable 28,551 14,284 Accrued payables for property sales — 16,296 Trade payables and other 13,681 6,540 Total accounts payable and accrued liabilities $ 111,309 $ 126,252 Environmental Liabilities. Environmental expenditures that relate to an existing condition caused by past operations and that do not contribute to current or future revenue generation are expensed. Environmental liabilities are accrued when environmental assessments and/or clean-ups are probable, and the costs can be reasonably estimated. Revenue Recognition. Oil, gas and NGL revenues are recognized when production is sold to a purchaser at a fixed or determinable price, when delivery has occurred and title has transferred, and collectability of the revenue is reasonably assured. The Company uses the sales method to account for gas and NGL imbalances. Under this method, revenues are recorded on the basis of gas and NGLs actually sold by the Company. In addition, the Company records revenues for its share of gas and NGLs sold by other owners that cannot be volumetrically balanced in the future due to insufficient remaining reserves. The Company also reduces revenues for other owners' volumetric share of gas and NGLs sold by the Company that cannot be volumetrically balanced in the future due to insufficient remaining reserves. The Company's remaining over- and under-produced gas and NGLs balancing positions are taken into account in determining the Company's proved oil, gas and NGL reserves. Imbalances at September 30, 2015 and 2014 were not material. Derivative Instruments and Hedging Activities. The Company periodically uses derivative financial instruments to achieve a more predictable cash flow from its oil, natural gas and NGL sales by reducing its exposure to price fluctuations. Derivative instruments are recorded at fair market value and are included in the Unaudited Consolidated Balance Sheets as assets or liabilities and in the Unaudited Consolidated Statements of Operations as commodity derivative gain (loss). Income Taxes. Income taxes are provided for the tax effects of transactions reported in the financial statements and consist of taxes currently payable plus deferred income taxes related to certain income and expenses recognized in different periods for financial and income tax reporting purposes. Deferred income tax assets and liabilities represent the future tax return consequences of those differences, which will either be taxable or deductible when assets are recovered or liabilities are settled. Deferred income taxes also include tax credits and net operating losses that are available to offset future income taxes. Deferred income taxes are measured by applying currently enacted tax rates. Deferred tax assets are regularly reviewed, considering all positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, taxable strategies and result of recent operations. The assumptions about future taxable income require significant judgment to determine whether it is more likely than not if the deferred tax asset is expected to be realized. The Company accounts for uncertainty in income taxes for tax positions taken or expected to be taken in a tax return. Only tax positions that meet the more-likely-than-not recognition threshold are recognized. The Company does not have any uncertain tax positions recorded as of September 30, 2015 . Earnings/Loss Per Share. Basic net income (loss) per common share is calculated by dividing net income (loss) attributable to common stock by the weighted average number of common shares outstanding during each period. Diluted net income per common share is calculated by dividing net income attributable to common stock by the weighted average number of common shares outstanding and other dilutive securities. Potentially dilutive securities for the diluted net income per common share calculations consist of nonvested equity shares of common stock, in-the-money outstanding stock options to purchase the Company's common stock and shares into which the Convertible Notes are convertible. No potential common shares are included in the computation of any diluted per share amount when a net loss exists, as was the case for the three and nine months ended September 30, 2015 and 2014 . The following table sets forth the calculation of basic and diluted income (loss) per share: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands, except per share amounts) Net income (loss) $ (410,314 ) $ (34,649 ) $ (466,626 ) $ (73,984 ) Basic weighted-average common shares outstanding in period 48,340 48,060 48,280 47,983 Add dilutive effects of stock options and nonvested equity shares of common stock — — — — Diluted weighted-average common shares outstanding in period 48,340 48,060 48,280 47,983 Basic net income (loss) per common share $ (8.49 ) $ (0.72 ) $ (9.67 ) $ (1.54 ) Diluted net income (loss) per common share $ (8.49 ) $ (0.72 ) $ (9.67 ) $ (1.54 ) New Accounting Pronouncements. In April 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2015-03, Simplifying the Presentation of Debt Issuance Costs . The objective of this update is to require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct reduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for the annual periods beginning after December 15, 2015, and for interim periods within that annual period. The adoption of the pronouncement will not have a significant impact on the Company’s disclosures and financial statements. In August 2014, the FASB issued ASU 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern. The objective of this update is to provide guidance in GAAP about management's responsibility to evaluate whether there is substantial doubt about an entity's ability to continue as a going concern and to provide related footnote disclosures. ASU 2014-15 is effective for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter. The standard will be adopted prospectively. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. The objective of this update is to clarify the principles for recognizing revenue and to develop a common revenue standard. In July 2015, the FASB issued a one year deferral of this standard changing the effective date to annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. The Company is currently evaluating the impact of adopting this standard.

Supplemental Disclosures of Cas

Supplemental Disclosures of Cash Flow Information	9 Months Ended
	Sep. 30, 2015
Supplemental Cash Flow Elements [Abstract]
Supplemental Disclosures of Cash Flow Information	Supplemental Disclosures of Cash Flow Information Supplemental cash flow information is as follows: Nine Months Ended September 30, 2015 2014 (in thousands) Cash paid for interest $ 31,323 $ 36,267 Cash paid for income taxes 1,052 1 Supplemental disclosures of non-cash investing and financing activities: Accrued liabilities - oil and gas properties 57,699 90,381 Change in asset retirement obligations, net of disposals (241 ) (23,327 ) Retirement of treasury stock (1,100 ) (2,462 ) Fair value of properties exchanged in non-cash transactions — 77,078 Relief from lease financing obligation — 36,106

Assets Held for Sale

Assets Held for Sale	9 Months Ended
	Sep. 30, 2015
Property, Plant and Equipment [Abstract]
Assets Held for Sale	Assets Held for Sale Assets are classified as held for sale when the Company commits to a plan to sell the assets and there is reasonable certainty the sale will take place within one year. Upon classification as held for sale, long-lived assets are no longer depreciated or depleted, and a measurement for impairment is performed to identify and expense any excess of carrying value over fair value less costs to sell. At September 30, 2015, the Company had a signed purchase and sale agreement in place for certain assets in the Uinta Basin and certain non-core assets in the DJ Basin. In addition, the Company began marketing the remainder of its non-core assets in the DJ Basin during the three months ended September 30, 2015. Therefore, the related assets and liabilities were classified as held for sale in the Unaudited Consolidated Balance Sheet as of September 30, 2015. Assets held for sale are recorded at the lesser of their respective carrying value or fair value less estimated costs to sell. The fair value of the assets held for sale was $57.3 million and was presented as oil and gas properties held for sale, net of amortization and impairment, of $64.9 million and liabilities associated with assets held for sale of $7.6 million on the Unaudited Consolidated Balance Sheet as of September 30, 2015.

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt The Company's outstanding debt is summarized below: As of September 30, 2015 As of December 31, 2014 Maturity Date Principal Unamortized Discount Carrying Amount Principal Unamortized Discount Carrying Amount (in thousands) Amended Credit Facility April 9, 2020 $ — $ — $ — $ — $ — $ — Convertible Notes (1) March 15, 2028 (2) 579 — 579 25,344 — 25,344 7.625% Senior Notes (3) October 1, 2019 400,000 — 400,000 400,000 — 400,000 7.0% Senior Notes (4) October 15, 2022 400,000 — 400,000 400,000 — 400,000 Lease Financing Obligation (5) August 10, 2020 3,330 — 3,330 3,648 — 3,648 Total Debt $ 803,909 $ — $ 803,909 $ 828,992 $ — $ 828,992 Less: Current Portion of Long-Term Debt (6) 1,015 — 1,015 25,770 — 25,770 Total Long-Term Debt $ 802,894 $ — $ 802,894 $ 803,222 $ — $ 803,222 (1) The aggregate estimated fair value of the Convertible Notes was approximately $0.6 million and $25.1 million as of September 30, 2015 and December 31, 2014 , respectively, based on reported market trades of these instruments. On March 20, 2015, the holders put 98% of the Convertible Notes to the Company, leaving $0.6 million principal amount remaining. (2) The Company has the right at any time, with at least 30 days' notice, to call the remaining Convertible Notes, and the holders have the right to require the Company to purchase the notes on each of March 20, 2018 and March 20, 2023. (3) The aggregate estimated fair value of the 7.625% Senior Notes was approximately $292.8 million and $359.8 million as of September 30, 2015 and December 31, 2014 , respectively, based on reported market trades of these instruments. (4) The aggregate estimated fair value of the 7.0% Senior Notes was approximately $257.0 million and $366.0 million as of September 30, 2015 and December 31, 2014 , respectively, based on reported market trades of these instruments. (5) The aggregate estimated fair value of the Lease Financing Obligation was approximately $3.2 million as of September 30, 2015 and $3.5 million as of December 31, 2014 . Because there is no active, public market for the Lease Financing Obligation, the aggregate estimated fair value was based on market-based parameters of comparable term secured financing instruments. (6) The current portion of the long-term debt as of September 30, 2015 and December 31, 2014 includes the current portion of the Lease Financing Obligation and the principal amount of the Convertible Notes. Amended Credit Facility On September 23, 2015, the Company entered into a Fourth Amendment (the "Fourth Amendment") to the Third Amended and Restated Credit Agreement dated March 16, 2010 (the "Amended Credit Facility"). The Fourth Amendment, among other things, reaffirmed the current borrowing base at $375.0 million and amended certain financial covenant requirements. On April 9, 2015, the Company entered into a Third Amendment (the "Third Amendment") to the Amended Credit Facility. The Third Amendment amended the definition of "Maturity Date" in the Amended Credit Facility to mean the earliest of (a) April 9, 2020 or (b) the date 181 days prior to the maturity of certain unsecured senior or senior subordinated debt of the Company in existence as of the date of the Third Amendment or that may be incurred by the Company as of a future date, or any permitted refinancing debt in respect thereof. The Amended Credit Facility currently has commitments and a borrowing base of $375.0 million from 13 lenders based on mid-year 2015 reserves and hedge position. Due to the Third Amendment, the Company recognized interest expense of $1.6 million and a loss on extinguishment of debt of $0.8 million on the Unaudited Consolidated Statements of Operations related to the acceleration of deferred financing charges during the nine months ended September 30, 2015. As of September 30, 2015 , the Company had no amounts outstanding under the Amended Credit Facility. As credit support for future payment under a contractual obligation, a $26.0 million letter of credit was issued under the Amended Credit Facility, which reduced the available borrowing capacity of the Amended Credit Facility as of September 30, 2015 to $349.0 million . Interest rates are LIBOR plus applicable margins of 1.5% to 2.5% or ABR plus 0.5% to 1.5% and the unused commitment fee is between 0.375% and 0.5% based on borrowing base utilization. There have not been any borrowings under the Amended Credit Facility in 2015. The average annual interest rate incurred on the Amended Credit Facility was 2.0% and 1.9% for the three and nine months ended September 30, 2014 , respectively. The borrowing base is required to be re-determined at least twice per year, on or about April 1 and October 1, as well as following any material property sales. Future borrowing bases will be computed based on proved oil, natural gas and NGL reserves, hedge positions and estimated future cash flows from those reserves calculated using future commodity pricing provided by our lenders, as well as any other outstanding debt of the Company. The Amended Credit Facility contains certain financial covenants. The Company is currently in compliance with all financial covenants and has complied with all financial covenants from the time it entered into the facility. 5% Convertible Senior Notes Due 2028 On March 12, 2008, the Company issued $172.5 million aggregate principal amount of Convertible Notes. On March 20, 2012, $147.2 million of the outstanding principal amount, or approximately 85% of the outstanding Convertible Notes, were put to the Company and redeemed by the Company at par. On March 20, 2015, $24.8 million of the remaining outstanding principal amount, or approximately 98% of the remaining outstanding Convertible Notes, were put to the Company and redeemed by the Company at par. The Company settled the notes in cash and recognized a gain on extinguishment of $2.6 million in the Unaudited Consolidated Statements of Operations for the nine months ended September 30, 2015 . After the redemption, $0.6 million aggregate principal amount of the Convertible Notes were outstanding as of September 30, 2015 . The Convertible Notes mature on March 15, 2028 , unless earlier converted, redeemed or purchased by the Company. The Convertible Notes are senior unsecured obligations and rank equal in right of payment to all of the Company's existing and future senior unsecured indebtedness, are senior in right of payment to all of the Company's future subordinated indebtedness, and are effectively subordinated to all of the Company's secured indebtedness with respect to the collateral securing such indebtedness. The Convertible Notes are structurally subordinated to all present and future secured and unsecured debt and other obligations of the Company's subsidiaries. The Convertible Notes are fully and unconditionally guaranteed by the subsidiaries that guarantee the Company's indebtedness under the Amended Credit Facility, the 7.625% Senior Notes and the 7.0% Senior Notes. The Convertible Notes bear interest at a rate of 5% per annum, payable semi-annually in arrears on March 15 and September 15 of each year. Holders of the remaining Convertible Notes may require the Company to purchase all or a portion of their Convertible Notes for cash on each of March 20, 2018 and March 20, 2023 at a purchase price equal to 100% of the principal amount of the Convertible Notes to be repurchased, plus accrued and unpaid interest, if any, up to but excluding the applicable purchase date. The Company has the right with at least 30 days' notice to call the Convertible Notes. 7.625% Senior Notes Due 2019 On September 27, 2011, the Company issued $400.0 million in principal amount of 7.625% Senior Notes due 2019 at par. The 7.625% Senior Notes mature on October 1, 2019 . Interest is payable in arrears semi-annually on April 1 and October 1 of each year. The 7.625% Senior Notes are senior unsecured obligations of the Company and rank equal in right of payment with all of the Company's other existing and future senior unsecured indebtedness, including the Convertible Notes and 7.0% Senior Notes. The 7.625% Senior Notes are redeemable at the Company's option beginning on October 1, 2015 at an initial redemption price of 103.813% of the principal amount of the notes. The 7.625% Senior Notes are fully and unconditionally guaranteed by the subsidiaries that guarantee the Company's indebtedness under the Amended Credit Facility, the Convertible Notes and the 7.0% Senior Notes. The 7.625% Senior Notes include certain covenants that limit the Company's ability to incur additional indebtedness, make restricted payments, create liens or sell assets and that generally prohibit the Company from paying dividends. The Company is currently in compliance with all financial covenants and has complied with all financial covenants since issuance. 7.0% Senior Notes Due 2022 On March 12, 2012, the Company issued $400.0 million in aggregate principal amount of 7.0% Senior Notes due 2022 at par. The 7.0% Senior Notes mature on October 15, 2022 . Interest is payable in arrears semi-annually on April 15 and October 15 of each year. The 7.0% Senior Notes are senior unsecured obligations and rank equal in right of payment with all of the Company's other existing and future senior unsecured indebtedness, including the Convertible Notes and 7.625% Senior Notes. The 7.0% Senior Notes are redeemable at the Company's option beginning on October 15, 2017 at an initial redemption price of 103.5% of the principal amount of the notes. The 7.0% Senior Notes are fully and unconditionally guaranteed by the subsidiaries that guarantee the Company's indebtedness under the Amended Credit Facility, the Convertible Notes and the 7.625% Senior Notes. The 7.0% Senior Notes include certain covenants that limit the Company's ability to incur additional indebtedness, make restricted payments, create liens or sell assets and that generally prohibit the Company from paying dividends. The Company is currently in compliance with all financial covenants and has complied with all financial covenants since issuance. Lease Financing Obligation Due 2020 The Company has a lease financing obligation with a balance of $3.3 million as of September 30, 2015 whereby the Company sold and subsequently leased back certain compressors and related facilities owned by the Company. The Lease Financing Obligation expires on August 10, 2020 , and the Company has the option to purchase the equipment at the end of the lease term for the then current fair market value. The Lease Financing Obligation also contains an early buyout option pursuant to which the Company may purchase the equipment for $1.8 million on February 10, 2019. The lease payments related to the equipment are recognized as principal and interest expense based on a weighted average implicit interest rate of 3.3% . See Note 12 for discussion of aggregate minimum future lease payments. The following table summarizes, for the periods indicated, the cash or accrued portion of interest expense related to the Amended Credit Facility, the outstanding Convertible Notes, the 7.625% Senior Notes, the 7.0% Senior Notes and the Lease Financing Obligation along with the non-cash portion resulting from the amortization of the debt discount and transaction costs through interest expense: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands) Amended Credit Facility (1) Cash interest $ 443 $ 1,771 $ 1,313 $ 4,392 Non-cash interest (2) $ 165 $ 586 $ 2,534 $ 1,757 Convertible Notes (3) Cash interest $ 22 $ 306 $ 308 $ 940 Non-cash interest $ 1 $ 1 $ 6 $ 4 7.625% Senior Notes (4) Cash interest $ 7,625 $ 7,625 $ 22,875 $ 22,875 Non-cash interest $ 267 $ 273 $ 813 $ 817 7.0% Senior Notes (5) Cash interest $ 7,000 $ 7,000 $ 21,000 $ 21,000 Non-cash interest $ 199 $ 204 $ 607 $ 610 Lease Financing Obligation (6) Cash interest $ 27 $ 248 $ 84 $ 765 Non-cash interest $ — $ 3 $ 24 $ 11 (1) Cash interest includes amounts related to interest and commitment fees incurred on the Amended Credit Facility and participation and fronting fees paid on the letter of credit. (2) Amount shown for the nine months ended September 30, 2015 includes $1.6 million related to amending the Amended Credit Facility. (3) The stated interest rate for the Convertible Notes is 5% per annum. The effective interest rate of the Convertible Notes includes amortization of the debt discount, which represented the fair value of the equity conversion feature at the time of issue. The stated interest rate of 5% on the Convertible Notes will be the effective interest rate of the $0.6 million remaining principal balance, as the related debt discount was fully amortized as of March 31, 2012. (4) The stated interest rate for the 7.625% Senior Notes is 7.625% per annum with an effective interest rate of 8.0% per annum. (5) The stated interest rate for the 7.0% Senior Notes is 7.0% per annum with an effective interest rate of 7.2% per annum. (6) The effective interest rate for the Lease Financing Obligation is 3.3% per annum. The decrease in cash interest for the three and nine months ended September 30, 2015 compared to the three and nine months ended September 30, 2014 was due to obligations transferring with the sale of natural gas assets in the Piceance Basin during the third quarter of 2014.

Asset Retirement Obligations

Asset Retirement Obligations	9 Months Ended
	Sep. 30, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	Asset Retirement Obligations A reconciliation of the Company's asset retirement obligations for the nine months ended September 30, 2015 is as follows (in thousands): As of December 31, 2014 $ 22,852 Liabilities incurred 754 Liabilities settled (162 ) Disposition of properties (745 ) Accretion expense 1,091 Revisions to estimate (88 ) As of September 30, 2015 $ 23,702 Less: liabilities associated with assets held for sale 7,641 Less: current asset retirement obligations 1,362 Long-term asset retirement obligations $ 14,699

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Assets and Liabilities Measured on a Recurring Basis The Company's financial instruments, including cash and cash equivalents, accounts and notes receivable and accounts payable are carried at cost, which approximates fair value due to the short-term maturity of these instruments. The recorded value of the Amended Credit Facility, as discussed in Note 5 , approximates its fair value due to its floating rate structure based on the LIBOR spread and the Company's borrowing base utilization. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). The Company utilizes a mid-market pricing convention (the mid-point price between bid and ask prices) for valuation as a practical expedient for assigning fair value. The Company uses market data or assumptions that market participants would use in pricing the asset or liability, including assumptions about risk. These inputs can be readily observable, market corroborated or generally unobservable. The Company primarily applies the market and income approaches for recurring fair value measurements and utilizes the best available information. Given the Company's historical market transactions, its markets and instruments are fairly liquid. Therefore, the Company has been able to classify fair value balances based on the observability of those inputs. A fair value hierarchy was established that prioritizes the inputs used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). Level 1 – Quoted prices are available in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. Level 1 primarily consists of financial instruments such as exchange-traded derivatives, listed securities and U.S. government treasury securities. Level 2 – Pricing inputs are other than quoted prices in active markets included in Level 1, which are either directly or indirectly observable as of the reporting date. Level 2 includes those financial instruments that are valued using models or other valuation methodologies. These models are primarily industry-standard models that consider various assumptions, including quoted forward prices for commodities, time value, volatility factors and current market and contractual prices for the underlying instruments, as well as other relevant economic measures. Substantially all of these assumptions are observable in the marketplace throughout the full term of the instrument, can be derived from observable data or are supported by observable levels at which transactions are executed in the marketplace. Instruments in this category include non-exchange-traded derivatives such as over-the-counter forwards and options. Level 3 – Pricing inputs include significant inputs that are generally less observable than objective sources. These inputs may be used with internally developed methodologies that result in management's best estimate of fair value. At each balance sheet date, the Company performs an analysis of all applicable instruments and includes in Level 3 all of those whose fair value is based on significant unobservable inputs. The following tables set forth by level within the fair value hierarchy the Company's financial assets and financial liabilities that were measured at fair value on a recurring basis. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company's assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of assets and liabilities and their placement within the fair value hierarchy levels. As of September 30, 2015 Level 1 Level 2 Level 3 Total (in thousands) Assets Deferred Compensation Plan $ 1,080 $ — $ — $ 1,080 Cash Equivalents 40,054 — — 40,054 Commodity Derivatives — 142,056 — 142,056 As of December 31, 2014 Level 1 Level 2 Level 3 Total (in thousands) Assets Deferred Compensation Plan $ 1,069 $ — $ — $ 1,069 Cash Equivalents 75,066 — — 75,066 Commodity Derivatives — 195,176 — 195,176 Liabilities Commodity Derivatives $ — $ 200 $ — $ 200 The commodity derivatives reflected in the table above and in the Unaudited Consolidated Balance Sheets have been adjusted for non-performance risk. For applicable financial assets carried at fair value, the credit standing of the counterparties is analyzed and factored into the fair value measurement of those assets. In addition, the fair value measurement of a liability has been adjusted to reflect the nonperformance risk of the Company. The following methods and assumptions were used to estimate the fair values of the assets and liabilities in the table above. Level 1 Fair Value Measurements – The Company maintains a non-qualified deferred compensation plan which allows certain management employees to defer receipt of a portion of their compensation. The Company maintains assets for the deferred compensation plan in a rabbi trust. The assets of the rabbi trust are invested in publicly traded mutual funds and are recorded in other current and other long-term assets in the Unaudited Consolidated Balance Sheets. The highly liquid cash equivalents are recorded at carrying value, which approximates fair value, which represent Level 1 inputs. The deferred compensation plan financial assets are reported at fair value based on active market quotes, which represent Level 1 inputs. The fair values of the Company's fixed rate 7.625% Senior Notes and 7.0% Senior Notes totaled $549.8 million as of September 30, 2015 . The fair values of the Company's fixed rate 7.625% Senior Notes and 7.0% Senior Notes totaled $725.8 million as of December 31, 2014 . The fair values of the Company's fixed rate Senior Notes are based on active market quotes, which represent Level 1 inputs. Level 2 Fair Value Measurements – The fair value of crude oil, natural gas and NGL forwards and options are estimated using a combined income and market valuation methodology with a mid-market pricing convention based upon forward commodity price and volatility curves. The curves are obtained from independent pricing services reflecting broker market quotes. The Company did not make any adjustments to the obtained curves. The pricing services publish observable market information from multiple brokers and exchanges. No proprietary models are used by the pricing services for the inputs. The Company utilized the counterparties' valuations to assess the reasonableness of the Company's valuations. There is no active, public market for the Amended Credit Facility, Convertible Notes or Lease Financing Obligation. The Amended Credit Facility had a balance of zero as of September 30, 2015 and December 31, 2014 . The Convertible Notes fair values of $0.6 million and $25.1 million as of September 30, 2015 and December 31, 2014 , respectively, are measured based on market-based parameters of the various components of the Convertible Notes and over the counter trades. The Lease Financing Obligation fair values of $3.2 million and $3.5 million as of September 30, 2015 and December 31, 2014 , respectively, are measured based on market-based parameters of comparable term secured financing instruments. The fair value measurements for the Amended Credit Facility, Convertible Notes and Lease Financing Obligation represent Level 2 inputs. Level 3 Fair Value Measurements – As of September 30, 2015 and December 31, 2014 , the Company did not have assets or liabilities that were measured on a recurring basis classified under a Level 3 fair value hierarchy. Assets and Liabilities Measured on a Non-recurring Basis – Oil and gas property costs are evaluated for impairment and reduced to fair value when there is an indication that the carrying costs may not be recoverable. The fair value is determined by using either a market approach based on recent sales prices of comparable properties and/or indications from marketing activities or by using the income valuation technique which involves calculating the present value of future revenues. The present value, net of estimated operating and development costs, is calculated using estimates of reserves, future commodity pricing, future production estimates, anticipated capital expenditures and various discount rates commensurate with the risk and current market conditions associated with realizing the projected cash flows (all of which are designated as Level 3 inputs within the fair value hierarchy). During the nine months ended September 30, 2015 , the Company reduced its Uinta Oil Program assets to a fair value of $180.0 million , resulting in a non-cash impairment charge of $571.9 million . Properties classified as held for sale are valued using a market approach, based on an estimated selling price, as evidenced by current marketing activities, if possible. If an estimated selling price is not available, the Company utilizes the income valuation technique discussed above. The fair value of assets classified as held for sale was $64.9 million as of September 30, 2015 . The following tables set forth by level within the fair value hierarchy the Company's non-financial assets and liabilities that were measured at fair value on a nonrecurring basis as of September 30, 2015. Net Carrying Value as of September 30, 2015 Fair Value Measurements Using Level 1 Level 2 Level 3 (in thousands) Proved property (1)(2) $ 225,363 $ — $ — $ 225,363 Unproved property (1)(2) 19,519 — — 19,519 (1) See Note 2 for additional details on impairment expense recognized. (2) Includes $50.3 million of net proved property and $14.6 million of net unproved property associated with properties held for sale as of September 30, 2015. See note 4 for additional details related to assets held for sale. During the year ended December 31, 2014, the Company recognized impairment on proved and unproved property of $39.8 million . Included in the total impairment charge of $39.8 million was $21.1 million of impairment charges related to the remaining Powder River Basin assets for which the Company utilized third party purchase offers as the basis for determining fair value. This property was classified as held for sale as of December 31, 2014. The following tables set forth by level within the fair value hierarchy the Company's non-financial assets and liabilities that were measured at fair value on a nonrecurring basis as of December 31, 2014. Net Carrying Value as of December 31, 2014 Impairment for the Year Ended December 31, 2014 Level 1 Level 2 Level 3 (in thousands) Proved property (1)(2) $ 1,588,038 $ — $ — $ 15,761 Unproved property (1)(2) 151,368 — — 24,082 (1) See Note 2 for additional details on impairment expense recognized. (2) Includes $6.7 million of net proved property and $2.5 million of net unproved property associated with properties held for sale as of December 31, 2014.

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments The Company uses financial derivative instruments as part of its price risk management program to achieve a more predictable cash flow from its production revenues by reducing its exposure to commodity price fluctuations. The Company has entered into financial commodity swap contracts related to the sale of a portion of the Company's production. The Company does not enter into derivative instruments for speculative or trading purposes. In addition to financial contracts, the Company may at times be party to various physical commodity contracts for the sale of oil, natural gas and NGLs that have varying terms and pricing provisions. These physical commodity contracts qualify for the normal purchase and normal sale exception and, therefore, are not subject to hedge or mark-to-market accounting. The financial impact of physical commodity contracts is included in oil, natural gas and NGL production revenues at the time of settlement. All derivative instruments, other than those that meet the normal purchase and normal sale exception, as mentioned above, are recorded at fair value and included in the Unaudited Consolidated Balance Sheets as assets or liabilities. The following table summarizes the location, as well as the gross and net fair value amounts of all derivative instruments presented in the Unaudited Consolidated Balance Sheets as of the dates indicated. As of September 30, 2015 Balance Sheet Gross Amounts of Recognized Derivative Assets Gross Amounts Offset in the Balance Sheet Net Amounts of Derivative Assets Presented in the Balance Sheet (in thousands) Derivative assets (current) $ 109,847 $ — $ 109,847 Derivative assets (noncurrent) 32,209 — 32,209 Total derivative assets $ 142,056 $ — $ 142,056 As of December 31, 2014 Balance Sheet Gross Amounts of Recognized Derivative Assets Gross Amounts Offset in the Balance Sheet Net Amounts of Derivative Assets Presented in the Balance Sheet (in thousands) Derivative assets (current) $ 145,426 $ (200 ) (1) $ 145,226 Derivative assets (noncurrent) 49,750 — 49,750 Total derivative assets $ 195,176 $ (200 ) $ 194,976 Gross Amounts of Recognized Derivative Liabilities Gross Amounts Offset in the Balance Sheet Net Amounts of Derivative Liabilities Presented in the Balance Sheet (in thousands) Derivative liabilities $ (200 ) $ 200 (2) $ — Total derivative liabilities $ (200 ) $ 200 $ — (1) Amounts are netted against derivative asset balances with the same counterparty and are therefore, presented as a net asset on the Unaudited Consolidated Balance Sheets. (2) Amounts are netted against derivative liability balances with the same counterparty and are therefore, presented as a net liability on the Unaudited Consolidated Balance Sheets. As of September 30, 2015 , the Company had financial derivative instruments in place related to the sale of a portion of the Company's production for the following volumes for the periods indicated: October – December 2015 For the year 2016 For the year 2017 Derivative Weighted Average Price Derivative Volumes Weighted Average Price Derivative Volumes Weighted Average Price Oil (Bbls) 993,600 $ 89.81 2,478,600 $ 80.47 683,250 $ 75.61 Natural Gas (MMbtu) 1,840,000 $ 4.13 1,830,000 $ 4.10 — $ — The table below summarizes the commodity derivative gains and losses the Company recognized related to its oil, gas and NGL derivative instruments for the periods indicated: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands) Commodity derivative gain (loss) settlements on derivatives designated as cash flow hedges (1) $ — $ 351 $ — $ 889 Total commodity derivative gain (loss) (2) 69,133 72,299 75,914 369 (1) Included in oil, gas and NGL production revenues in the Unaudited Consolidated Statements of Operations. (2) Included in commodity derivative gain (loss) in the Unaudited Consolidated Statements of Operations. The Company's derivative financial instruments are generally executed with major financial or commodities trading institutions that expose the Company to market and credit risks and may, at times, be concentrated with certain counterparties or groups of counterparties. The Company had derivatives in place with eight different counterparties as of September 30, 2015 . Although notional amounts are used to express the volume of these contracts, the amounts potentially subject to credit risk, in the event of non-performance by the counterparties, are substantially smaller. The creditworthiness of counterparties is subject to continual review by management, and the Company believes all of these institutions currently are acceptable credit risks. Full performance is anticipated, and the Company has no past due receivables from any of its counterparties. It is the Company's policy to enter into derivative contracts with counterparties that are lenders in the Amended Credit Facility or affiliates of lenders in the Amended Credit Facility. The Company's derivative contracts are documented using an industry standard contract known as a Schedule to the Master Agreement and International Swaps and Derivative Association, Inc. ("ISDA") Master Agreement or other contracts. Typical terms for these contracts include credit support requirements, cross default provisions, termination events and set-off provisions. The Company is not required to provide any credit support to its counterparties other than cross collateralization with the properties securing the Amended Credit Facility. The Company has set-off provisions in its derivative contracts with lenders under its Amended Credit Facility which, in the event of a counterparty default, allow the Company to set-off amounts owed to the defaulting counterparty under the Amended Credit Facility or other obligations against monies owed to the Company under the derivative contracts. Where the counterparty is not a lender under the Company's Amended Credit Facility, it may not be able to set-off amounts owed by the Company under the Amended Credit Facility, even if such counterparty is an affiliate of a lender under such facility. The Company does not have any derivative balances that are offset by cash collateral.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company accounts for uncertainty in income taxes for tax positions taken or expected to be taken in a tax return in accordance with the FASB’s rules on income taxes. The Company recognizes the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained upon examination by the taxing authorities. During the three and nine months ended September 30, 2015 , the Company had no uncertain tax positions. The Company’s policy is to classify accrued penalties and interest related to unrecognized tax benefits in the Company’s income tax provision. The Company did not record any accrued interest or penalties associated with unrecognized tax benefits during the three and nine months ended September 30, 2015 and 2014 . At September 30, 2015 the Company recorded a non-cash impairment charge of $571.9 million against its proved and unproved oil and gas properties. Primarily as a result of this non-cash impairment charge the Company was put into a net deferred tax asset position after applying the appropriate and expected jurisdictional tax rates at September 30, 2015 . The Company considers all available evidence (both positive and negative) to estimate whether sufficient future taxable income will be generated to permit the use of the existing deferred tax assets. Such evidence includes the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in making this assessment, and judgment is required in considering the relative weight of negative and positive evidence. Accordingly the Company recorded a valuation allowance of $66.4 million against our net deferred tax asset. The Company continues to monitor facts and circumstances in the reassessment of the likelihood that operating loss carryforwards, credits and other deferred tax assets will be utilized prior to their expiration. Any increases or decreases in a deferred tax asset valuation allowance would impact net income through offsetting changes in income tax expense. Income tax benefit for the three and nine months ended September 30, 2015 and 2014 differs from the amounts that would be provided by applying the U.S. statutory income tax rates to pretax income or loss principally due to the effect of deferred tax asset valuation allowances, stock based compensation, political lobbying expense, political contributions, nondeductible officer compensation and state income taxes. For the three and nine months ended September 30, 2015 the effective tax rate decreased as a result of recording a valuation allowance of $66.4 million against the deferred tax asset balance.

Equity Incentive Compensation P

Equity Incentive Compensation Plans and Other Long-term Incentive Programs	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Incentive Compensation Plans and Other Long-term Incentive Programs	Equity Incentive Compensation Plans and Other Long-term Incentive Programs The Company maintains various stock-based compensation plans and other employee benefits as discussed below. Stock-based compensation is measured at the grant date based on the value of the awards, and the fair value is recognized on a straight-line basis over the requisite service period (usually the vesting period). The following table presents the non-cash stock-based compensation related to equity awards for the periods indicated: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands) Common stock options $ 137 $ 482 $ 528 $ 1,608 Nonvested common stock 1,816 1,760 5,007 4,979 Nonvested common stock units 250 274 779 783 Nonvested performance-based shares (50 ) 955 903 1,919 Total $ 2,153 $ 3,471 $ 7,217 $ 9,289 Unrecognized compensation cost as of September 30, 2015 was $16.5 million related to grants of nonvested stock options and nonvested shares of common stock that are expected to be recognized over a weighted-average period of 2.1 years . Nonvested Shares. The following table presents the equity awards granted pursuant to the Company's various stock compensation plans: Three Months Ended September 30, 2015 Three Months Ended September 30, 2014 Number of Weighted Average Number of Weighted Average Nonvested common stock 32,618 $ 5.24 26,828 $ 21.53 Nonvested common stock units 5,681 $ 3.30 850 $ 22.04 Nonvested performance-based shares — $ — 10,073 $ 18.52 Total shares granted 38,299 37,751 Nine Months Ended September 30, 2015 Nine Months Ended September 30, 2014 Number of Weighted Average Number of Weighted Average Nonvested common stock 664,757 $ 11.91 516,768 $ 22.49 Nonvested common stock units 130,669 $ 8.47 44,282 $ 24.98 Nonvested performance-based shares — $ — 303,188 $ 19.77 Total shares granted 795,426 864,238 Performance Cash Program 2015 Program. In February 2015, the Compensation Committee approved a performance cash program (the "2015 Program") granting performance cash units that will settle in cash. The performance-based awards contingently vest in May 2018, depending on the level at which the performance goals are achieved. The performance goals, which will be measured over the three year period ending December 31, 2017, consist of the Company's total shareholder return ("TSR") ranking relative to a defined peer group's individual TSRs ("Relative TSR") (weighted at 60% ) and the percentage change in discretionary cash flow per debt adjusted share relative to a defined peer group's percentage calculation ("DCF per Debt Adjusted Share") (weighted at 40% ). The Relative TSR and DCF per Debt Adjusted Share goals will vest at 25% or 50% of the total award for performance met at the threshold level, 100% at the target level and 200% at the stretch level. If the actual results for a metric are between the threshold and target levels or between the target and stretch levels, the vested number of units will be prorated based on the actual results compared to the threshold, target and stretch goals. If the threshold metrics are not met, no units will vest. In any event, the total number of units that could vest will not exceed 200% of the original number of performance cash units granted. At the end of the three year vesting period, any units that have not vested will be forfeited. A total of 409,046 units were granted under this program during the nine months ended September 30, 2015 . The Company recognized $0.3 million in derivatives and other noncurrent liabilities in the Unaudited Consolidated Balance Sheets as of September 30, 2015 and a $0.1 million decrease in general and administrative expense and $0.3 million in general and administrative expense in the Unaudited Consolidated Statements of Operations for the three and nine months ended September 30, 2015 , respectively, for the 2015 Program.

Equity Distribution Agreement

Equity Distribution Agreement	9 Months Ended
	Sep. 30, 2015
Equity Distribution Agreement [Abstract]
Equity Distribution Agreement [Text Block]	Equity Distribution Agreement On June 10, 2015, the Company entered into an Equity Distribution Agreement (the "Agreement") with Goldman, Sachs and Co. (the "Manager"). Pursuant to the terms of the Agreement, the Company may sell, from time to time through or to the Manager, shares of its common stock having an aggregate gross sales price of up to $100.0 million . Sales of the shares, if any, will be made by means of ordinary brokers' transactions through the facilities of the New York Stock Exchange, at market prices, in block transactions, to or through a market maker, through an electronic communications network or as otherwise agreed by the Company and the Manager. As of September 30, 2015, no shares have been sold pursuant to the Agreement.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Financing Obligation. The Company has a Lease Financing Obligation with Bank of America Leasing & Capital, LLC as the lead bank as discussed in Note 5 . The aggregate undiscounted minimum future lease payments, including both principal and interest components, are presented below: As of September 30, 2015 (in thousands) 2015 $ 135 2016 537 2017 537 2018 537 2019 1,825 Thereafter — Total $ 3,571 Transportation Charges . The Company is party to two firm transportation contracts to provide capacity on natural gas pipeline systems. The remaining term on these contracts is six years. The contracts require the Company to pay transportation charges regardless of the amount of pipeline capacity utilized by the Company. Beginning October 1, 2014, these transportation costs were excluded from gathering, transportation and processing expense and included in unused commitments expense in the Unaudited Consolidated Statements of Operations. As a result of previous divestitures during 2013 and 2014, the Company will likely not utilize the firm capacity on the natural gas pipelines. The amounts in the table below represent the Company's future minimum transportation charges. As of September 30, 2015 (in thousands) 2015 $ 4,576 2016 18,692 2017 18,692 2018 18,692 2019 18,692 Thereafter 29,595 Total $ 108,939 Purchase Commitments. The Company has one take-or-pay purchase agreement for supply of carbon dioxide ("CO2"), which has a total financial commitment of $1.5 million . The CO2 is for use in fracture stimulation operations. Under this contract, the Company is obligated to purchase a minimum volume of CO2 at a set price. If the Company takes delivery of less than the minimum required amount, the Company is responsible for full payment (deficiency payment) in December 2015. Lease and Other Commitments. The Company leases office space, vehicles and certain equipment under non-cancelable operating leases. Additionally, the Company has entered into various long-term agreements for telecommunication services as well as other drilling and throughput commitments. Future minimum annual payments under lease and other agreements are as follows: As of September 30, 2015 (in thousands) 2015 (1)(2) $ 2,646 2016 2,995 2017 2,892 2018 2,591 2019 633 Thereafter — Total $ 11,757 (1) Includes a contractual obligation of $1.3 million due October 1, 2015 related to certain drilling commitments on sold properties. (2) Includes a sales throughput contract in the South Altamont area of the Uinta Oil Basin. Under this contract, the Company is obligated to sell and deliver a minimum volume commitment ("MVC") of 450.0 MMcf for the period of December 1, 2014 to November 30, 2015. If the minimum volume is not delivered, the Company must make a deficiency payment of up to $0.8 million . As of September 30, 2015 , the Company had satisfied approximately 190.2 MMcf of this commitment, resulting in an estimated deficiency payment of up to $0.4 million due December 1, 2015. Litigation. The Company is subject to litigation, claims and governmental and regulatory proceedings arising in the ordinary course of business. It is the opinion of the Company's management that current claims and litigation involving the Company are not likely to have a material adverse effect on its Unaudited Consolidated Balance Sheet, Cash Flows or Statements of Operations.

Guarantor Subsidiaries

Guarantor Subsidiaries	9 Months Ended
	Sep. 30, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Guarantor Subsidiaries	Guarantor Subsidiaries In addition to the Amended Credit Facility, the 7.625% Senior Notes, 7.0% Senior Notes and Convertible Notes, which have been registered under the Securities Act of 1933, are jointly and severally guaranteed on a full and unconditional basis by the Company's 100% owned subsidiaries ("Guarantor Subsidiaries"). Presented below are the Company's unaudited condensed consolidating balance sheets, statements of operations, statements of other comprehensive income (loss) and statements of cash flows, as required by Securities and Exchange Commission ("SEC") Rule 3-10 of Regulation S-X. During the six months ended June 30, 2014, Bill Barrett Corporation, as parent, merged two of the Company's 100% owned subsidiaries, CBM Production Company and GB Acquisition Corporation, into the parent company. During the six months ended June 30, 2015, Bill Barrett Corporation, as parent, merged another 100% owned subsidiary, Elk Production Uintah, LLC, into the parent company. The unaudited condensed consolidating financial statements reflect the new guarantor structure for all periods presented. The following unaudited condensed consolidating financial statements have been prepared from the Company's financial information on the same basis of accounting as the Unaudited Consolidated Financial Statements. Investments in the subsidiaries are accounted for under the equity method. Accordingly, the entries necessary to consolidate the Company and the Guarantor Subsidiaries are reflected in the intercompany eliminations column. Condensed Consolidating Balance Sheets As of September 30, 2015 Parent Guarantor Intercompany Consolidated (in thousands) Assets: Current assets $ 270,062 $ 78 $ — $ 270,140 Property and equipment, net 1,232,180 6,767 — 1,238,947 Intercompany receivable (payable) 21,416 (21,416 ) — — Investment in subsidiaries (14,716 ) — 14,716 — Noncurrent assets 87,173 — — 87,173 Total assets $ 1,596,115 $ (14,571 ) $ 14,716 $ 1,596,260 Liabilities and Stockholders' Equity: Current liabilities $ 200,120 $ 94 $ — $ 200,214 Long-term debt 802,894 — — 802,894 Other noncurrent liabilities 25,335 51 — 25,386 Stockholders' equity 567,766 (14,716 ) 14,716 567,766 Total liabilities and stockholders' equity $ 1,596,115 $ (14,571 ) $ 14,716 $ 1,596,260 As of December 31, 2014 Parent Guarantor Intercompany Consolidated (in thousands) Assets: Current assets $ 426,103 $ 2 $ — $ 426,105 Property and equipment, net 1,730,074 23,047 — 1,753,121 Intercompany receivable (payable) 22,840 (22,840 ) — — Investment in subsidiaries 163 — (163 ) — Noncurrent assets 65,258 — — 65,258 Total assets $ 2,244,438 $ 209 $ (163 ) $ 2,244,484 Liabilities and Stockholders' Equity: Current liabilities $ 264,687 $ — $ — $ 264,687 Long-term debt 803,222 — — 803,222 Deferred income taxes 122,350 — — 122,350 Other noncurrent liabilities 24,691 46 — 24,737 Stockholders' equity 1,029,488 163 (163 ) 1,029,488 Total liabilities and stockholders' equity $ 2,244,438 $ 209 $ (163 ) $ 2,244,484 Condensed Consolidating Statements of Operations Three Months Ended September 30, 2015 Parent Guarantor Intercompany Consolidated (in thousands) Operating and other revenues $ 49,562 $ 117 $ — $ 49,679 Operating expenses (630,783 ) (14,929 ) — (645,712 ) General and administrative (11,025 ) — — (11,025 ) Interest income and other income (expense) 53,479 — — 53,479 Income (loss) before income taxes and equity in earnings of subsidiaries (538,767 ) (14,812 ) — (553,579 ) (Provision for) Benefit from income taxes 143,265 — — 143,265 Equity in earnings (loss) of subsidiaries (14,812 ) — 14,812 — Net income (loss) $ (410,314 ) $ (14,812 ) $ 14,812 $ (410,314 ) Nine Months Ended September 30, 2015 Parent Guarantor Intercompany Consolidated (in thousands) Operating and other revenues $ 160,963 $ 368 $ — $ 161,331 Operating expenses (779,377 ) (15,247 ) — (794,624 ) General and administrative (39,026 ) — — (39,026 ) Interest income and other income (expense) 28,608 — — 28,608 Income (loss) before income taxes and equity in earnings of subsidiaries (628,832 ) (14,879 ) — (643,711 ) (Provision for) Benefit from income taxes 177,085 — — 177,085 Equity in earnings (loss) of subsidiaries (14,879 ) — 14,879 — Net income (loss) $ (466,626 ) $ (14,879 ) $ 14,879 $ (466,626 ) Three Months Ended September 30, 2014 Parent Guarantor Intercompany Consolidated (in thousands) Operating and other revenues $ 135,263 $ — $ — $ 135,263 Operating expenses (235,123 ) (62 ) — (235,185 ) General and administrative (11,111 ) — — (11,111 ) Interest and other income (expense) 54,530 — — 54,530 Income (loss) before income taxes and equity in earnings of subsidiaries (56,441 ) (62 ) — (56,503 ) (Provision for) Benefit from income taxes 21,854 — — 21,854 Equity in earnings of subsidiaries (62 ) — 62 — Net income (loss) $ (34,649 ) $ (62 ) $ 62 $ (34,649 ) Nine Months Ended September 30, 2014 Parent Guarantor Intercompany Consolidated (in thousands) Operating and other revenues $ 405,398 $ (9 ) $ — $ 405,389 Operating expenses (429,560 ) (192 ) — (429,752 ) General and administrative (41,039 ) — — (41,039 ) Interest and other income (expense) (51,960 ) 35 — (51,925 ) Income (loss) before income taxes and equity in earnings of subsidiaries (117,161 ) (166 ) — (117,327 ) (Provision for) Benefit from income taxes 43,343 — — 43,343 Equity in earnings (loss) of subsidiaries (166 ) — 166 — Net income (loss) $ (73,984 ) $ (166 ) $ 166 $ (73,984 ) Condensed Consolidating Statements of Comprehensive Income (Loss) Three Months Ended September 30, 2015 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Net income (loss) $ (410,314 ) $ (14,812 ) $ 14,812 $ (410,314 ) Other Comprehensive Income (Loss), net of tax: Effect of derivative financial instruments — — — — Other comprehensive income (loss) — — — — Comprehensive income (loss) $ (410,314 ) $ (14,812 ) $ 14,812 $ (410,314 ) Nine Months Ended September 30, 2015 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Net income (loss) $ (466,626 ) $ (14,879 ) $ 14,879 $ (466,626 ) Other Comprehensive Income (Loss), net of tax: Effect of derivative financial instruments — — — — Other comprehensive income (loss) — — — — Comprehensive income (loss) $ (466,626 ) $ (14,879 ) $ 14,879 $ (466,626 ) Three Months Ended September 30, 2014 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Net income (loss) $ (34,649 ) $ (62 ) $ 62 $ (34,649 ) Other Comprehensive Income (Loss), net of tax: Effect of derivative financial instruments (219 ) — — (219 ) Other comprehensive income (loss) (219 ) — — (219 ) Comprehensive income (loss) $ (34,868 ) $ (62 ) $ 62 $ (34,868 ) Nine Months Ended September 30, 2014 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Net income (loss) $ (73,984 ) $ (166 ) $ 166 $ (73,984 ) Other Comprehensive Income (Loss), net of tax: Effect of derivative financial instruments (555 ) — — (555 ) Other comprehensive income (loss) (555 ) — — (555 ) Comprehensive income (loss) $ (74,539 ) $ (166 ) $ 166 $ (74,539 ) Condensed Consolidating Statements of Cash Flows Nine Months Ended September 30, 2015 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Cash flows from operating activities $ 165,911 $ (10 ) $ — $ 165,901 Cash flows from investing activities: Additions to oil and gas properties, including acquisitions (257,399 ) 1,340 — (256,059 ) Additions to furniture, fixtures and other (1,036 ) — — (1,036 ) Proceeds from sale of properties and other investing activities 66,617 — — 66,617 Cash paid for short-term investments (114,883 ) — — (114,883 ) Proceeds from sale of short-term investments 95,000 — — 95,000 Intercompany transfers 1,330 — (1,330 ) — Cash flows from financing activities: Proceeds from debt — — — — Principal payments on debt (25,083 ) — — (25,083 ) Intercompany transfers — (1,330 ) 1,330 — Other financing activities (3,525 ) — — (3,525 ) Change in cash and cash equivalents (73,068 ) — — (73,068 ) Beginning cash and cash equivalents 165,904 — — 165,904 Ending cash and cash equivalents $ 92,836 $ — $ — $ 92,836 Nine Months Ended September 30, 2014 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Cash flows from operating activities $ 231,274 $ 28 $ — $ 231,302 Cash flows from investing activities: Additions to oil and gas properties, including acquisitions (419,268 ) (6,710 ) — (425,978 ) Additions to furniture, fixtures and other (2,110 ) — — (2,110 ) Proceeds from sale of properties and other investing activities 555,926 1,821 — 557,747 Intercompany transfers (4,861 ) — 4,861 — Cash flows from financing activities: Proceeds from debt 165,000 — — 165,000 Principal payments on debt (283,442 ) — — (283,442 ) Intercompany transfers — 4,861 (4,861 ) — Other financing activities (2,336 ) — — (2,336 ) Change in cash and cash equivalents 240,183 — — 240,183 Beginning cash and cash equivalents 54,595 — — 54,595 Ending cash and cash equivalents $ 294,778 $ — $ — $ 294,778

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On October 21, 2015, the Company entered into a purchase and sale agreement for the sale of the Company’s remaining non-core assets in the DJ Basin. Total consideration, prior to customary closing adjustments, was $23.0 million . The transaction is expected to close by the end of 2015. The related assets and liabilities were classified as held for sale in the Unaudited Consolidated Balance Sheet as of September 30, 2015.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation. The accompanying Unaudited Consolidated Financial Statements include the accounts of the Company. These statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP"). All intercompany accounts and transactions have been eliminated in consolidation. In the opinion of management, the accompanying financial statements include all adjustments (consisting of normal recurring accruals and adjustments) necessary to present fairly, in all material respects, the Company's interim results. However, operating results for the periods presented are not necessarily indicative of the results that may be expected for the full year. The Company's Annual Report on Form 10-K includes certain definitions and a summary of significant accounting policies and should be read in conjunction with this Quarterly Report on Form 10-Q. Except as disclosed herein, there have been no material changes to the information disclosed in the notes to the consolidated financial statements included in the Company's 2014 Annual Report on Form 10-K.
Use of Estimates	Use of Estimates. In the course of preparing the Company's financial statements in accordance with GAAP, management makes various assumptions, judgments and estimates to determine the reported amount of assets, liabilities, revenues and expenses and in the disclosure of commitments and contingencies. Changes in these assumptions, judgments and estimates will occur as a result of the passage of time and the occurrence of future events and, accordingly, actual results could differ from amounts initially established. Areas requiring the use of assumptions, judgments and estimates relate to volumes of oil, natural gas and NGL reserves used in calculating depreciation, depletion and amortization ("DD&A"), the amount of expected future cash flows used in determining possible impairments of proved oil and gas properties and the amount of future capital costs used in these calculations. Assumptions, judgments and estimates also are required in determining asset retirement obligations, the timing of dry hole costs, impairments of unproved oil and gas properties, valuing deferred tax assets and estimating fair values of derivative instruments and stock-based compensation awards.
Oil and Gas Properties	Oil and Gas Properties. The Company's oil, gas and NGL exploration and production activities are accounted for using the successful efforts method. Under this method, all property acquisition costs and costs of exploratory and development wells are capitalized when incurred, pending determination of whether the well has found proved reserves. If an exploratory well does not find proved reserves, the costs of drilling the well are charged to expense and remain within cash flows from investing activities in the Unaudited Consolidated Statements of Cash Flows. If an exploratory well does find proved reserves, the costs remain capitalized and are included within additions to oil and gas properties and remain within cash flows from investing activities in the Unaudited Consolidated Statements of Cash Flows. The costs of development wells are capitalized whether proved reserves are added or not. Oil and gas lease acquisition costs are also capitalized. Upon sale or retirement of depreciable or depletable property, the cost and related accumulated DD&A are eliminated from the accounts and the resulting gain or loss is recognized. Other exploration costs, including certain geological and geophysical expenses and delay rentals for oil and gas leases, are charged to expense as incurred. The sale of a partial interest in a proved property is accounted for as a cost recovery and no gain or loss is recognized as long as this treatment does not significantly affect the unit-of-production amortization rate. Maintenance and repairs are charged to expense, and renewals and betterments are capitalized to the appropriate property and equipment accounts. Unproved oil and gas property costs are transferred to proved oil and gas properties if the properties are subsequently determined to be productive or are assigned proved reserves. Proceeds from sales of partial interests in unproved leases are accounted for as a recovery of cost without recognizing any gain until all costs are recovered. Unproved oil and gas properties are assessed periodically for impairment based on remaining lease terms, drilling results, reservoir performance, commodity price outlooks, future plans to develop acreage and other relevant matters. Materials and supplies consist primarily of tubular goods and well equipment to be used in future drilling operations or repair operations and are carried at the lower of cost or market value, on a first-in, first-out basis. The following table sets forth the net capitalized costs and associated accumulated DD&A and non-cash impairments relating to the Company's oil, natural gas and NGL producing activities: As of September 30, 2015 As of December 31, 2014 (in thousands) Proved properties $ 321,201 $ 390,482 Wells and related equipment and facilities 1,536,447 1,537,370 Support equipment and facilities 74,438 68,371 Materials and supplies 9,990 13,069 Total proved oil and gas properties $ 1,942,076 $ 2,009,292 Unproved properties 28,514 78,898 Wells and facilities in progress 66,699 69,936 Total unproved oil and gas properties, excluded from amortization $ 95,213 $ 148,834 Assets held for sale 64,882 9,234 Accumulated depreciation, depletion, amortization and impairment (875,852 ) (427,954 ) Total oil and gas properties, net $ 1,226,319 $ 1,739,406 The Company reviews proved oil and gas properties on a field-by-field basis for impairment on a quarterly basis or whenever events and circumstances indicate that a decline in the recoverability of their carrying value may have occurred. The Company estimates the expected undiscounted future net cash flows of its oil and gas properties based on the Company's best estimate of development plans, future production, commodity pricing, gathering and transportation deductions, production tax rates, lease operating expenses and future development costs. The Company compares such undiscounted future net cash flows to the carrying amount of the oil and gas properties to determine if the carrying amount is recoverable. If the undiscounted future net cash flows exceed the carrying amount of the proved oil and gas properties, no impairment is taken. If the carrying value of a property exceeds the undiscounted future net cash flows, the Company will impair the carrying value to fair value based on an analysis of quantitative and qualitative factors existing as of the balance sheet date. The Company does not believe that the undiscounted future net cash flows analysis of its proved property represents the applicable market value. The factors used to determine fair value include, but are not limited to, recent sales prices of comparable properties, indications from marketing activities, the present value of future revenues, net of estimated operating and development costs using estimates of reserves, future commodity pricing, future production estimates, anticipated capital expenditures and various discount rates commensurate with the risk and current market conditions associated with realizing the projected cash flows. The Company recognized non-cash impairment, dry hole costs and abandonment expense in the Unaudited Consolidated Statements of Operations, as follows: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands) Non-cash impairment of proved oil and gas properties $ 556,291 (1) $ 11,493 (2) $ 556,563 (1) $ 12,531 (2)(3) Non-cash impairment of unproved oil and gas properties 15,572 (1) 15,250 (2) 15,803 (1) 15,250 (2) Non-cash impairment of inventory — — — 340 Dry hole costs 14 3 (29 ) 96 Abandonment expense and lease expirations 774 2,363 2,659 4,396 Total non-cash impairment, dry hole costs and abandonment expense $ 572,651 $ 29,109 $ 574,996 $ 32,613 (1) Due to the continued decline in oil prices, the Company recognized a non-cash impairment charge associated with the Company's Uinta Oil Program proved and unproved oil and gas properties for the three and nine months ended September 30, 2015. (2) As a result of the sale or exchange of the majority of the Company's Powder River Basin assets ("Powder River Oil Divestiture") and results of drilling and completion activity in the Paradox Basin during the three months ended September 30, 2014, the remaining carrying values of Powder River Oil and Paradox Basin assets were analyzed relative to their estimated fair market values. As a result, the Company recognized proved and unproved property impairments of $11.5 million and $15.3 million , respectively. (3) The amount shown reflects $1.0 million of proved impairment expense that was incurred during the nine months ended September 30, 2014 related to the sale of the Company's West Tavaputs natural gas assets in the Uinta Basin ("West Tavaputs Divestiture") based upon a true up of previously estimated fair value relative to carrying value. These assets were sold in December 2013. The provision for DD&A of oil and gas properties is calculated on a field-by-field basis using the unit-of-production method. Natural gas and NGLs are converted to an oil equivalent, Boe, at the standard rate of six Mcf to one Boe and forty-two gallons to one Boe, respectively. Estimated future dismantlement, restoration and abandonment costs are taken into consideration by this calculation.
Accounts Payable and Accrued Liabilities	Accounts Payable and Accrued Liabilities. Accounts payable and accrued liabilities are comprised of the following: As of September 30, 2015 As of December 31, 2014 (in thousands) Accrued drilling, completion and facility costs $ 49,664 $ 68,124 Accrued lease operating, gathering, transportation and processing expenses 10,718 12,526 Accrued general and administrative expenses 8,695 8,482 Accrued interest payable 28,551 14,284 Accrued payables for property sales — 16,296 Trade payables and other 13,681 6,540 Total accounts payable and accrued liabilities $ 111,309 $ 126,252
Environmental Liabilities	Environmental Liabilities. Environmental expenditures that relate to an existing condition caused by past operations and that do not contribute to current or future revenue generation are expensed. Environmental liabilities are accrued when environmental assessments and/or clean-ups are probable, and the costs can be reasonably estimated.
Revenue Recognition	Revenue Recognition. Oil, gas and NGL revenues are recognized when production is sold to a purchaser at a fixed or determinable price, when delivery has occurred and title has transferred, and collectability of the revenue is reasonably assured. The Company uses the sales method to account for gas and NGL imbalances. Under this method, revenues are recorded on the basis of gas and NGLs actually sold by the Company. In addition, the Company records revenues for its share of gas and NGLs sold by other owners that cannot be volumetrically balanced in the future due to insufficient remaining reserves. The Company also reduces revenues for other owners' volumetric share of gas and NGLs sold by the Company that cannot be volumetrically balanced in the future due to insufficient remaining reserves. The Company's remaining over- and under-produced gas and NGLs balancing positions are taken into account in determining the Company's proved oil, gas and NGL reserves. Imbalances at September 30, 2015 and 2014 were not material.
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities. The Company periodically uses derivative financial instruments to achieve a more predictable cash flow from its oil, natural gas and NGL sales by reducing its exposure to price fluctuations. Derivative instruments are recorded at fair market value and are included in the Unaudited Consolidated Balance Sheets as assets or liabilities and in the Unaudited Consolidated Statements of Operations as commodity derivative gain (loss).
Income Taxes	Income Taxes. Income taxes are provided for the tax effects of transactions reported in the financial statements and consist of taxes currently payable plus deferred income taxes related to certain income and expenses recognized in different periods for financial and income tax reporting purposes. Deferred income tax assets and liabilities represent the future tax return consequences of those differences, which will either be taxable or deductible when assets are recovered or liabilities are settled. Deferred income taxes also include tax credits and net operating losses that are available to offset future income taxes. Deferred income taxes are measured by applying currently enacted tax rates. Deferred tax assets are regularly reviewed, considering all positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, taxable strategies and result of recent operations. The assumptions about future taxable income require significant judgment to determine whether it is more likely than not if the deferred tax asset is expected to be realized. The Company accounts for uncertainty in income taxes for tax positions taken or expected to be taken in a tax return. Only tax positions that meet the more-likely-than-not recognition threshold are recognized. The Company does not have any uncertain tax positions recorded as of September 30, 2015 .
Earnings/Loss Per Share	Earnings/Loss Per Share. Basic net income (loss) per common share is calculated by dividing net income (loss) attributable to common stock by the weighted average number of common shares outstanding during each period. Diluted net income per common share is calculated by dividing net income attributable to common stock by the weighted average number of common shares outstanding and other dilutive securities. Potentially dilutive securities for the diluted net income per common share calculations consist of nonvested equity shares of common stock, in-the-money outstanding stock options to purchase the Company's common stock and shares into which the Convertible Notes are convertible. No potential common shares are included in the computation of any diluted per share amount when a net loss exists, as was the case for the three and nine months ended September 30, 2015 and 2014 . The following table sets forth the calculation of basic and diluted income (loss) per share: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands, except per share amounts) Net income (loss) $ (410,314 ) $ (34,649 ) $ (466,626 ) $ (73,984 ) Basic weighted-average common shares outstanding in period 48,340 48,060 48,280 47,983 Add dilutive effects of stock options and nonvested equity shares of common stock — — — — Diluted weighted-average common shares outstanding in period 48,340 48,060 48,280 47,983 Basic net income (loss) per common share $ (8.49 ) $ (0.72 ) $ (9.67 ) $ (1.54 ) Diluted net income (loss) per common share $ (8.49 ) $ (0.72 ) $ (9.67 ) $ (1.54 )
New Accounting Pronouncements	New Accounting Pronouncements. In April 2015, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") 2015-03, Simplifying the Presentation of Debt Issuance Costs . The objective of this update is to require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct reduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for the annual periods beginning after December 15, 2015, and for interim periods within that annual period. The adoption of the pronouncement will not have a significant impact on the Company’s disclosures and financial statements. In August 2014, the FASB issued ASU 2014-15, Disclosure of Uncertainties about an Entity's Ability to Continue as a Going Concern. The objective of this update is to provide guidance in GAAP about management's responsibility to evaluate whether there is substantial doubt about an entity's ability to continue as a going concern and to provide related footnote disclosures. ASU 2014-15 is effective for the annual period ending after December 15, 2016, and for annual periods and interim periods thereafter. The standard will be adopted prospectively. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers. The objective of this update is to clarify the principles for recognizing revenue and to develop a common revenue standard. In July 2015, the FASB issued a one year deferral of this standard changing the effective date to annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. The Company is currently evaluating the impact of adopting this standard.

Summary of Significant Accoun24

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2015
Accounting Policies [Abstract]
Summary of Accounts Receivable	Accounts receivable is comprised of the following: As of September 30, 2015 As of December 31, 2014 (in thousands) Accrued oil, gas and NGL sales $ 33,018 $ 35,099 Due from joint interest owners 9,333 27,937 Other (1) 1,733 49,187 Allowance for doubtful accounts (14 ) (14 ) Total accounts receivable $ 44,070 $ 112,209 (1) Other as of December 31, 2014 includes a receivable of $47.6 million (including $4.7 million due to another industry partner) related to a settlement agreement with the Department of Interior resulting in the cancellation of certain Cottonwood Gulch natural gas leases during the three months ended December 31, 2014.
Net Capitalized Costs and Associated Accumulated DD&A and Non Cash Impairments	The following table sets forth the net capitalized costs and associated accumulated DD&A and non-cash impairments relating to the Company's oil, natural gas and NGL producing activities: As of September 30, 2015 As of December 31, 2014 (in thousands) Proved properties $ 321,201 $ 390,482 Wells and related equipment and facilities 1,536,447 1,537,370 Support equipment and facilities 74,438 68,371 Materials and supplies 9,990 13,069 Total proved oil and gas properties $ 1,942,076 $ 2,009,292 Unproved properties 28,514 78,898 Wells and facilities in progress 66,699 69,936 Total unproved oil and gas properties, excluded from amortization $ 95,213 $ 148,834 Assets held for sale 64,882 9,234 Accumulated depreciation, depletion, amortization and impairment (875,852 ) (427,954 ) Total oil and gas properties, net $ 1,226,319 $ 1,739,406
Non-Cash Impairment Charges, Included within Impairment, Dry Hole Costs and Abandonment Expense in Consolidated Statements of Operations	The Company recognized non-cash impairment, dry hole costs and abandonment expense in the Unaudited Consolidated Statements of Operations, as follows: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands) Non-cash impairment of proved oil and gas properties $ 556,291 (1) $ 11,493 (2) $ 556,563 (1) $ 12,531 (2)(3) Non-cash impairment of unproved oil and gas properties 15,572 (1) 15,250 (2) 15,803 (1) 15,250 (2) Non-cash impairment of inventory — — — 340 Dry hole costs 14 3 (29 ) 96 Abandonment expense and lease expirations 774 2,363 2,659 4,396 Total non-cash impairment, dry hole costs and abandonment expense $ 572,651 $ 29,109 $ 574,996 $ 32,613 (1) Due to the continued decline in oil prices, the Company recognized a non-cash impairment charge associated with the Company's Uinta Oil Program proved and unproved oil and gas properties for the three and nine months ended September 30, 2015. (2) As a result of the sale or exchange of the majority of the Company's Powder River Basin assets ("Powder River Oil Divestiture") and results of drilling and completion activity in the Paradox Basin during the three months ended September 30, 2014, the remaining carrying values of Powder River Oil and Paradox Basin assets were analyzed relative to their estimated fair market values. As a result, the Company recognized proved and unproved property impairments of $11.5 million and $15.3 million , respectively. (3) The amount shown reflects $1.0 million of proved impairment expense that was incurred during the nine months ended September 30, 2014 related to the sale of the Company's West Tavaputs natural gas assets in the Uinta Basin ("West Tavaputs Divestiture") based upon a true up of previously estimated fair value relative to carrying value. These assets were sold in December 2013.
Accounts Payable and Accrued Liabilities	Accounts payable and accrued liabilities are comprised of the following: As of September 30, 2015 As of December 31, 2014 (in thousands) Accrued drilling, completion and facility costs $ 49,664 $ 68,124 Accrued lease operating, gathering, transportation and processing expenses 10,718 12,526 Accrued general and administrative expenses 8,695 8,482 Accrued interest payable 28,551 14,284 Accrued payables for property sales — 16,296 Trade payables and other 13,681 6,540 Total accounts payable and accrued liabilities $ 111,309 $ 126,252
Calculation of Basic and Diluted Earnings (Loss) Per Share	The following table sets forth the calculation of basic and diluted income (loss) per share: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands, except per share amounts) Net income (loss) $ (410,314 ) $ (34,649 ) $ (466,626 ) $ (73,984 ) Basic weighted-average common shares outstanding in period 48,340 48,060 48,280 47,983 Add dilutive effects of stock options and nonvested equity shares of common stock — — — — Diluted weighted-average common shares outstanding in period 48,340 48,060 48,280 47,983 Basic net income (loss) per common share $ (8.49 ) $ (0.72 ) $ (9.67 ) $ (1.54 ) Diluted net income (loss) per common share $ (8.49 ) $ (0.72 ) $ (9.67 ) $ (1.54 )

Supplemental Disclosures of C25

Supplemental Disclosures of Cash Flow Information (Tables)	9 Months Ended
	Sep. 30, 2015
Supplemental Cash Flow Elements [Abstract]
Supplemental Cash Flow Information	Supplemental cash flow information is as follows: Nine Months Ended September 30, 2015 2014 (in thousands) Cash paid for interest $ 31,323 $ 36,267 Cash paid for income taxes 1,052 1 Supplemental disclosures of non-cash investing and financing activities: Accrued liabilities - oil and gas properties 57,699 90,381 Change in asset retirement obligations, net of disposals (241 ) (23,327 ) Retirement of treasury stock (1,100 ) (2,462 ) Fair value of properties exchanged in non-cash transactions — 77,078 Relief from lease financing obligation — 36,106

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2015
Debt Disclosure [Abstract]
Outstanding Debt	The Company's outstanding debt is summarized below: As of September 30, 2015 As of December 31, 2014 Maturity Date Principal Unamortized Discount Carrying Amount Principal Unamortized Discount Carrying Amount (in thousands) Amended Credit Facility April 9, 2020 $ — $ — $ — $ — $ — $ — Convertible Notes (1) March 15, 2028 (2) 579 — 579 25,344 — 25,344 7.625% Senior Notes (3) October 1, 2019 400,000 — 400,000 400,000 — 400,000 7.0% Senior Notes (4) October 15, 2022 400,000 — 400,000 400,000 — 400,000 Lease Financing Obligation (5) August 10, 2020 3,330 — 3,330 3,648 — 3,648 Total Debt $ 803,909 $ — $ 803,909 $ 828,992 $ — $ 828,992 Less: Current Portion of Long-Term Debt (6) 1,015 — 1,015 25,770 — 25,770 Total Long-Term Debt $ 802,894 $ — $ 802,894 $ 803,222 $ — $ 803,222 (1) The aggregate estimated fair value of the Convertible Notes was approximately $0.6 million and $25.1 million as of September 30, 2015 and December 31, 2014 , respectively, based on reported market trades of these instruments. On March 20, 2015, the holders put 98% of the Convertible Notes to the Company, leaving $0.6 million principal amount remaining. (2) The Company has the right at any time, with at least 30 days' notice, to call the remaining Convertible Notes, and the holders have the right to require the Company to purchase the notes on each of March 20, 2018 and March 20, 2023. (3) The aggregate estimated fair value of the 7.625% Senior Notes was approximately $292.8 million and $359.8 million as of September 30, 2015 and December 31, 2014 , respectively, based on reported market trades of these instruments. (4) The aggregate estimated fair value of the 7.0% Senior Notes was approximately $257.0 million and $366.0 million as of September 30, 2015 and December 31, 2014 , respectively, based on reported market trades of these instruments. (5) The aggregate estimated fair value of the Lease Financing Obligation was approximately $3.2 million as of September 30, 2015 and $3.5 million as of December 31, 2014 . Because there is no active, public market for the Lease Financing Obligation, the aggregate estimated fair value was based on market-based parameters of comparable term secured financing instruments. (6) The current portion of the long-term debt as of September 30, 2015 and December 31, 2014 includes the current portion of the Lease Financing Obligation and the principal amount of the Convertible Notes.
Cash and Non-Cash Portion of Interest Expense Related to Long Term Debt	The following table summarizes, for the periods indicated, the cash or accrued portion of interest expense related to the Amended Credit Facility, the outstanding Convertible Notes, the 7.625% Senior Notes, the 7.0% Senior Notes and the Lease Financing Obligation along with the non-cash portion resulting from the amortization of the debt discount and transaction costs through interest expense: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands) Amended Credit Facility (1) Cash interest $ 443 $ 1,771 $ 1,313 $ 4,392 Non-cash interest (2) $ 165 $ 586 $ 2,534 $ 1,757 Convertible Notes (3) Cash interest $ 22 $ 306 $ 308 $ 940 Non-cash interest $ 1 $ 1 $ 6 $ 4 7.625% Senior Notes (4) Cash interest $ 7,625 $ 7,625 $ 22,875 $ 22,875 Non-cash interest $ 267 $ 273 $ 813 $ 817 7.0% Senior Notes (5) Cash interest $ 7,000 $ 7,000 $ 21,000 $ 21,000 Non-cash interest $ 199 $ 204 $ 607 $ 610 Lease Financing Obligation (6) Cash interest $ 27 $ 248 $ 84 $ 765 Non-cash interest $ — $ 3 $ 24 $ 11 (1) Cash interest includes amounts related to interest and commitment fees incurred on the Amended Credit Facility and participation and fronting fees paid on the letter of credit. (2) Amount shown for the nine months ended September 30, 2015 includes $1.6 million related to amending the Amended Credit Facility. (3) The stated interest rate for the Convertible Notes is 5% per annum. The effective interest rate of the Convertible Notes includes amortization of the debt discount, which represented the fair value of the equity conversion feature at the time of issue. The stated interest rate of 5% on the Convertible Notes will be the effective interest rate of the $0.6 million remaining principal balance, as the related debt discount was fully amortized as of March 31, 2012. (4) The stated interest rate for the 7.625% Senior Notes is 7.625% per annum with an effective interest rate of 8.0% per annum. (5) The stated interest rate for the 7.0% Senior Notes is 7.0% per annum with an effective interest rate of 7.2% per annum. (6) The effective interest rate for the Lease Financing Obligation is 3.3% per annum. The decrease in cash interest for the three and nine months ended September 30, 2015 compared to the three and nine months ended September 30, 2014 was due to obligations transferring with the sale of natural gas assets in the Piceance Basin during the third quarter of 2014.

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	9 Months Ended
	Sep. 30, 2015
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Asset Retirement Obligations	A reconciliation of the Company's asset retirement obligations for the nine months ended September 30, 2015 is as follows (in thousands): As of December 31, 2014 $ 22,852 Liabilities incurred 754 Liabilities settled (162 ) Disposition of properties (745 ) Accretion expense 1,091 Revisions to estimate (88 ) As of September 30, 2015 $ 23,702 Less: liabilities associated with assets held for sale 7,641 Less: current asset retirement obligations 1,362 Long-term asset retirement obligations $ 14,699

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2015
Fair Value Disclosures [Abstract]
Fair Value, Balance Sheet Grouping	The following tables set forth by level within the fair value hierarchy the Company's financial assets and financial liabilities that were measured at fair value on a recurring basis. Assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company's assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of assets and liabilities and their placement within the fair value hierarchy levels. As of September 30, 2015 Level 1 Level 2 Level 3 Total (in thousands) Assets Deferred Compensation Plan $ 1,080 $ — $ — $ 1,080 Cash Equivalents 40,054 — — 40,054 Commodity Derivatives — 142,056 — 142,056 As of December 31, 2014 Level 1 Level 2 Level 3 Total (in thousands) Assets Deferred Compensation Plan $ 1,069 $ — $ — $ 1,069 Cash Equivalents 75,066 — — 75,066 Commodity Derivatives — 195,176 — 195,176 Liabilities Commodity Derivatives $ — $ 200 $ — $ 200
Schedule Fair Value Measurements, Recurring and Nonrecurring	The following tables set forth by level within the fair value hierarchy the Company's non-financial assets and liabilities that were measured at fair value on a nonrecurring basis as of September 30, 2015. Net Carrying Value as of September 30, 2015 Fair Value Measurements Using Level 1 Level 2 Level 3 (in thousands) Proved property (1)(2) $ 225,363 $ — $ — $ 225,363 Unproved property (1)(2) 19,519 — — 19,519 (1) See Note 2 for additional details on impairment expense recognized. (2) Includes $50.3 million of net proved property and $14.6 million of net unproved property associated with properties held for sale as of September 30, 2015. See note 4 for additional details related to assets held for sale. During the year ended December 31, 2014, the Company recognized impairment on proved and unproved property of $39.8 million . Included in the total impairment charge of $39.8 million was $21.1 million of impairment charges related to the remaining Powder River Basin assets for which the Company utilized third party purchase offers as the basis for determining fair value. This property was classified as held for sale as of December 31, 2014. The following tables set forth by level within the fair value hierarchy the Company's non-financial assets and liabilities that were measured at fair value on a nonrecurring basis as of December 31, 2014. Net Carrying Value as of December 31, 2014 Impairment for the Year Ended December 31, 2014 Level 1 Level 2 Level 3 (in thousands) Proved property (1)(2) $ 1,588,038 $ — $ — $ 15,761 Unproved property (1)(2) 151,368 — — 24,082 (1) See Note 2 for additional details on impairment expense recognized. (2) Includes $6.7 million of net proved property and $2.5 million of net unproved property associated with properties held for sale as of December 31, 2014.

Derivative Instruments (Tables)

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value Amounts of Derivative Instruments	The following table summarizes the location, as well as the gross and net fair value amounts of all derivative instruments presented in the Unaudited Consolidated Balance Sheets as of the dates indicated. As of September 30, 2015 Balance Sheet Gross Amounts of Recognized Derivative Assets Gross Amounts Offset in the Balance Sheet Net Amounts of Derivative Assets Presented in the Balance Sheet (in thousands) Derivative assets (current) $ 109,847 $ — $ 109,847 Derivative assets (noncurrent) 32,209 — 32,209 Total derivative assets $ 142,056 $ — $ 142,056 As of December 31, 2014 Balance Sheet Gross Amounts of Recognized Derivative Assets Gross Amounts Offset in the Balance Sheet Net Amounts of Derivative Assets Presented in the Balance Sheet (in thousands) Derivative assets (current) $ 145,426 $ (200 ) (1) $ 145,226 Derivative assets (noncurrent) 49,750 — 49,750 Total derivative assets $ 195,176 $ (200 ) $ 194,976 Gross Amounts of Recognized Derivative Liabilities Gross Amounts Offset in the Balance Sheet Net Amounts of Derivative Liabilities Presented in the Balance Sheet (in thousands) Derivative liabilities $ (200 ) $ 200 (2) $ — Total derivative liabilities $ (200 ) $ 200 $ — (1) Amounts are netted against derivative asset balances with the same counterparty and are therefore, presented as a net asset on the Unaudited Consolidated Balance Sheets. (2) Amounts are netted against derivative liability balances with the same counterparty and are therefore, presented as a net liability on the Unaudited Consolidated Balance Sheets.
Financial Instruments for Hedging Volumes	As of September 30, 2015 , the Company had financial derivative instruments in place related to the sale of a portion of the Company's production for the following volumes for the periods indicated: October – December 2015 For the year 2016 For the year 2017 Derivative Weighted Average Price Derivative Volumes Weighted Average Price Derivative Volumes Weighted Average Price Oil (Bbls) 993,600 $ 89.81 2,478,600 $ 80.47 683,250 $ 75.61 Natural Gas (MMbtu) 1,840,000 $ 4.13 1,830,000 $ 4.10 — $ —
Realized and Unrealized Gains and Losses on Commodity Derivative Instruments	The table below summarizes the commodity derivative gains and losses the Company recognized related to its oil, gas and NGL derivative instruments for the periods indicated: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands) Commodity derivative gain (loss) settlements on derivatives designated as cash flow hedges (1) $ — $ 351 $ — $ 889 Total commodity derivative gain (loss) (2) 69,133 72,299 75,914 369 (1) Included in oil, gas and NGL production revenues in the Unaudited Consolidated Statements of Operations. (2) Included in commodity derivative gain (loss) in the Unaudited Consolidated Statements of Operations.

Equity Incentive Compensation30

Equity Incentive Compensation Plans and Other Long-term Incentive Programs (Tables)	9 Months Ended
	Sep. 30, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Non-Cash Stock-Based Compensation Cost Related to Equity Awards	The following table presents the non-cash stock-based compensation related to equity awards for the periods indicated: Three Months Ended September 30, Nine Months Ended September 30, 2015 2014 2015 2014 (in thousands) Common stock options $ 137 $ 482 $ 528 $ 1,608 Nonvested common stock 1,816 1,760 5,007 4,979 Nonvested common stock units 250 274 779 783 Nonvested performance-based shares (50 ) 955 903 1,919 Total $ 2,153 $ 3,471 $ 7,217 $ 9,289
Stock Options and Nonvested Equity Shares, Equity Awards Granted	The following table presents the equity awards granted pursuant to the Company's various stock compensation plans: Three Months Ended September 30, 2015 Three Months Ended September 30, 2014 Number of Weighted Average Number of Weighted Average Nonvested common stock 32,618 $ 5.24 26,828 $ 21.53 Nonvested common stock units 5,681 $ 3.30 850 $ 22.04 Nonvested performance-based shares — $ — 10,073 $ 18.52 Total shares granted 38,299 37,751 Nine Months Ended September 30, 2015 Nine Months Ended September 30, 2014 Number of Weighted Average Number of Weighted Average Nonvested common stock 664,757 $ 11.91 516,768 $ 22.49 Nonvested common stock units 130,669 $ 8.47 44,282 $ 24.98 Nonvested performance-based shares — $ — 303,188 $ 19.77 Total shares granted 795,426 864,238

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Aggregate Undiscounted Minimum Future Lease Payments	The Company has a Lease Financing Obligation with Bank of America Leasing & Capital, LLC as the lead bank as discussed in Note 5 . The aggregate undiscounted minimum future lease payments, including both principal and interest components, are presented below: As of September 30, 2015 (in thousands) 2015 $ 135 2016 537 2017 537 2018 537 2019 1,825 Thereafter — Total $ 3,571
Gross Future Minimum Transportation Demand and Firm Processing Charges	The amounts in the table below represent the Company's future minimum transportation charges. As of September 30, 2015 (in thousands) 2015 $ 4,576 2016 18,692 2017 18,692 2018 18,692 2019 18,692 Thereafter 29,595 Total $ 108,939
Future Minimum Annual Payments Under Drilling, Lease and Other Agreements	Future minimum annual payments under lease and other agreements are as follows: As of September 30, 2015 (in thousands) 2015 (1)(2) $ 2,646 2016 2,995 2017 2,892 2018 2,591 2019 633 Thereafter — Total $ 11,757 (1) Includes a contractual obligation of $1.3 million due October 1, 2015 related to certain drilling commitments on sold properties. (2) Includes a sales throughput contract in the South Altamont area of the Uinta Oil Basin. Under this contract, the Company is obligated to sell and deliver a minimum volume commitment ("MVC") of 450.0 MMcf for the period of December 1, 2014 to November 30, 2015. If the minimum volume is not delivered, the Company must make a deficiency payment of up to $0.8 million . As of September 30, 2015 , the Company had satisfied approximately 190.2 MMcf of this commitment, resulting in an estimated deficiency payment of up to $0.4 million due December 1, 2015.

Guarantor Subsidiaries (Tables)

Guarantor Subsidiaries (Tables)	9 Months Ended
	Sep. 30, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule of Condensed Consolidating Balance Sheets	Condensed Consolidating Balance Sheets As of September 30, 2015 Parent Guarantor Intercompany Consolidated (in thousands) Assets: Current assets $ 270,062 $ 78 $ — $ 270,140 Property and equipment, net 1,232,180 6,767 — 1,238,947 Intercompany receivable (payable) 21,416 (21,416 ) — — Investment in subsidiaries (14,716 ) — 14,716 — Noncurrent assets 87,173 — — 87,173 Total assets $ 1,596,115 $ (14,571 ) $ 14,716 $ 1,596,260 Liabilities and Stockholders' Equity: Current liabilities $ 200,120 $ 94 $ — $ 200,214 Long-term debt 802,894 — — 802,894 Other noncurrent liabilities 25,335 51 — 25,386 Stockholders' equity 567,766 (14,716 ) 14,716 567,766 Total liabilities and stockholders' equity $ 1,596,115 $ (14,571 ) $ 14,716 $ 1,596,260 As of December 31, 2014 Parent Guarantor Intercompany Consolidated (in thousands) Assets: Current assets $ 426,103 $ 2 $ — $ 426,105 Property and equipment, net 1,730,074 23,047 — 1,753,121 Intercompany receivable (payable) 22,840 (22,840 ) — — Investment in subsidiaries 163 — (163 ) — Noncurrent assets 65,258 — — 65,258 Total assets $ 2,244,438 $ 209 $ (163 ) $ 2,244,484 Liabilities and Stockholders' Equity: Current liabilities $ 264,687 $ — $ — $ 264,687 Long-term debt 803,222 — — 803,222 Deferred income taxes 122,350 — — 122,350 Other noncurrent liabilities 24,691 46 — 24,737 Stockholders' equity 1,029,488 163 (163 ) 1,029,488 Total liabilities and stockholders' equity $ 2,244,438 $ 209 $ (163 ) $ 2,244,484
Schedule of Condensed Consolidating Statements of Operations	Condensed Consolidating Statements of Operations Three Months Ended September 30, 2015 Parent Guarantor Intercompany Consolidated (in thousands) Operating and other revenues $ 49,562 $ 117 $ — $ 49,679 Operating expenses (630,783 ) (14,929 ) — (645,712 ) General and administrative (11,025 ) — — (11,025 ) Interest income and other income (expense) 53,479 — — 53,479 Income (loss) before income taxes and equity in earnings of subsidiaries (538,767 ) (14,812 ) — (553,579 ) (Provision for) Benefit from income taxes 143,265 — — 143,265 Equity in earnings (loss) of subsidiaries (14,812 ) — 14,812 — Net income (loss) $ (410,314 ) $ (14,812 ) $ 14,812 $ (410,314 ) Nine Months Ended September 30, 2015 Parent Guarantor Intercompany Consolidated (in thousands) Operating and other revenues $ 160,963 $ 368 $ — $ 161,331 Operating expenses (779,377 ) (15,247 ) — (794,624 ) General and administrative (39,026 ) — — (39,026 ) Interest income and other income (expense) 28,608 — — 28,608 Income (loss) before income taxes and equity in earnings of subsidiaries (628,832 ) (14,879 ) — (643,711 ) (Provision for) Benefit from income taxes 177,085 — — 177,085 Equity in earnings (loss) of subsidiaries (14,879 ) — 14,879 — Net income (loss) $ (466,626 ) $ (14,879 ) $ 14,879 $ (466,626 ) Three Months Ended September 30, 2014 Parent Guarantor Intercompany Consolidated (in thousands) Operating and other revenues $ 135,263 $ — $ — $ 135,263 Operating expenses (235,123 ) (62 ) — (235,185 ) General and administrative (11,111 ) — — (11,111 ) Interest and other income (expense) 54,530 — — 54,530 Income (loss) before income taxes and equity in earnings of subsidiaries (56,441 ) (62 ) — (56,503 ) (Provision for) Benefit from income taxes 21,854 — — 21,854 Equity in earnings of subsidiaries (62 ) — 62 — Net income (loss) $ (34,649 ) $ (62 ) $ 62 $ (34,649 ) Nine Months Ended September 30, 2014 Parent Guarantor Intercompany Consolidated (in thousands) Operating and other revenues $ 405,398 $ (9 ) $ — $ 405,389 Operating expenses (429,560 ) (192 ) — (429,752 ) General and administrative (41,039 ) — — (41,039 ) Interest and other income (expense) (51,960 ) 35 — (51,925 ) Income (loss) before income taxes and equity in earnings of subsidiaries (117,161 ) (166 ) — (117,327 ) (Provision for) Benefit from income taxes 43,343 — — 43,343 Equity in earnings (loss) of subsidiaries (166 ) — 166 — Net income (loss) $ (73,984 ) $ (166 ) $ 166 $ (73,984 )
Schedule of Condensed Consolidating Statements of Comprehensive Income (Loss)	Condensed Consolidating Statements of Comprehensive Income (Loss) Three Months Ended September 30, 2015 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Net income (loss) $ (410,314 ) $ (14,812 ) $ 14,812 $ (410,314 ) Other Comprehensive Income (Loss), net of tax: Effect of derivative financial instruments — — — — Other comprehensive income (loss) — — — — Comprehensive income (loss) $ (410,314 ) $ (14,812 ) $ 14,812 $ (410,314 ) Nine Months Ended September 30, 2015 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Net income (loss) $ (466,626 ) $ (14,879 ) $ 14,879 $ (466,626 ) Other Comprehensive Income (Loss), net of tax: Effect of derivative financial instruments — — — — Other comprehensive income (loss) — — — — Comprehensive income (loss) $ (466,626 ) $ (14,879 ) $ 14,879 $ (466,626 ) Three Months Ended September 30, 2014 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Net income (loss) $ (34,649 ) $ (62 ) $ 62 $ (34,649 ) Other Comprehensive Income (Loss), net of tax: Effect of derivative financial instruments (219 ) — — (219 ) Other comprehensive income (loss) (219 ) — — (219 ) Comprehensive income (loss) $ (34,868 ) $ (62 ) $ 62 $ (34,868 ) Nine Months Ended September 30, 2014 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Net income (loss) $ (73,984 ) $ (166 ) $ 166 $ (73,984 ) Other Comprehensive Income (Loss), net of tax: Effect of derivative financial instruments (555 ) — — (555 ) Other comprehensive income (loss) (555 ) — — (555 ) Comprehensive income (loss) $ (74,539 ) $ (166 ) $ 166 $ (74,539 )
Schedule of Condensed Consolidating Statements of Cash Flows	Condensed Consolidating Statements of Cash Flows Nine Months Ended September 30, 2015 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Cash flows from operating activities $ 165,911 $ (10 ) $ — $ 165,901 Cash flows from investing activities: Additions to oil and gas properties, including acquisitions (257,399 ) 1,340 — (256,059 ) Additions to furniture, fixtures and other (1,036 ) — — (1,036 ) Proceeds from sale of properties and other investing activities 66,617 — — 66,617 Cash paid for short-term investments (114,883 ) — — (114,883 ) Proceeds from sale of short-term investments 95,000 — — 95,000 Intercompany transfers 1,330 — (1,330 ) — Cash flows from financing activities: Proceeds from debt — — — — Principal payments on debt (25,083 ) — — (25,083 ) Intercompany transfers — (1,330 ) 1,330 — Other financing activities (3,525 ) — — (3,525 ) Change in cash and cash equivalents (73,068 ) — — (73,068 ) Beginning cash and cash equivalents 165,904 — — 165,904 Ending cash and cash equivalents $ 92,836 $ — $ — $ 92,836 Nine Months Ended September 30, 2014 Parent Issuer Guarantor Subsidiaries Intercompany Eliminations Consolidated (in thousands) Cash flows from operating activities $ 231,274 $ 28 $ — $ 231,302 Cash flows from investing activities: Additions to oil and gas properties, including acquisitions (419,268 ) (6,710 ) — (425,978 ) Additions to furniture, fixtures and other (2,110 ) — — (2,110 ) Proceeds from sale of properties and other investing activities 555,926 1,821 — 557,747 Intercompany transfers (4,861 ) — 4,861 — Cash flows from financing activities: Proceeds from debt 165,000 — — 165,000 Principal payments on debt (283,442 ) — — (283,442 ) Intercompany transfers — 4,861 (4,861 ) — Other financing activities (2,336 ) — — (2,336 ) Change in cash and cash equivalents 240,183 — — 240,183 Beginning cash and cash equivalents 54,595 — — 54,595 Ending cash and cash equivalents $ 294,778 $ — $ — $ 294,778

Summary of Significant Accoun33

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Summary Of Significant Accounting Policies [Line Items]
Short-term investments	$ 19,992		$ 19,992		$ 0
Non-cash impairment of oil and gas properties	571,900				39,800
Proved Oil And Gas Properties [Member]
Summary Of Significant Accounting Policies [Line Items]
Non-cash impairment of oil and gas properties	556,291	$ 11,493	556,563	$ 12,531
Unproved Oil And Gas Properties [Member]
Summary Of Significant Accounting Policies [Line Items]
Non-cash impairment of oil and gas properties	$ 15,572	$ 15,250	$ 15,803	15,250
West Tavaputs, Proved [Member]
Summary Of Significant Accounting Policies [Line Items]
Non-cash impairment of oil and gas properties				$ 1,000
Less Receivable Due to Industry Partner [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts Receivable, Gross					4,700
Receivable from Department of Interior, Gross [Member]
Summary Of Significant Accounting Policies [Line Items]
Accounts Receivable, Gross					$ 47,600

Summary of Significant Accoun34

Summary of Significant Accounting Policies - Summary of Accounts Receivable (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for doubtful accounts	$ (14)	$ (14)
Accounts receivable	44,070	112,209
Accrued Oil, Gas, and NGL Sales
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable gross	33,018	35,099
Due from Joint Interest Owners
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable gross	9,333	27,937
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable gross	$ 1,733	$ 49,187

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Net Capitalized Costs and Associated Accumulated Depreciation, Depletion & Amortization and Non Cash Impairments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Proved properties	$ 321,201	$ 390,482
Wells and related equipment and facilities	1,536,447	1,537,370
Support equipment and facilities	74,438	68,371
Materials and supplies	9,990	13,069
Total proved oil and gas properties	1,942,076	2,009,292
Unproved properties	28,514	78,898
Wells and facilities in progress	66,699	69,936
Total unproved oil and gas properties, excluded from amortization	95,213	148,834
Assets held for sale	64,882	9,234
Accumulated depreciation, depletion, amortization and impairment	(875,852)	(427,954)
Total oil and gas properties, net	$ 1,226,319	$ 1,739,406

Summary of Significant Accoun36

Summary of Significant Accounting Policies - Non-Cash Impairment Charges, Included within Impairment, Dry Hole Costs and Abandonment Expense in Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Summary Of Significant Accounting Policies [Line Items]
Non-cash impairment of oil and gas properties	$ 571,900				$ 39,800
Non-cash impairment of inventory	0	$ 0	$ 0	$ 340
Dry hole costs	14	3	(29)	96
Abandonment expense and lease expirations	774	2,363	2,659	4,396
Impairment, dry hole costs and abandonment expense	572,651	29,109	574,996	32,613
Proved Oil And Gas Properties [Member]
Summary Of Significant Accounting Policies [Line Items]
Non-cash impairment of oil and gas properties	556,291	11,493	556,563	12,531
Unproved Oil And Gas Properties [Member]
Summary Of Significant Accounting Policies [Line Items]
Non-cash impairment of oil and gas properties	$ 15,572	$ 15,250	$ 15,803	$ 15,250

Summary of Significant Accoun37

Summary of Significant Accounting Policies - Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Accrued drilling, completion and facility costs	$ 49,664	$ 68,124
Accrued lease operating, gathering, transportation and processing expenses	10,718	12,526
Accrued general and administrative expenses	8,695	8,482
Accrued interest payable	28,551	14,284
Accrued payables for property sales	0	16,296
Trade payables and other	13,681	6,540
Total accounts payable and accrued liabilities	$ 111,309	$ 126,252

Summary of Significant Accoun38

Summary of Significant Accounting Policies - Calculation of Basic and Diluted Earnings (Loss) Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Accounting Policies [Abstract]
Net Income (Loss)	$ (410,314)	$ (34,649)	$ (466,626)	$ (73,984)	$ 15,081
Basic weighted-average common shares outstanding in period (in shares)	48,339,639	48,060,086	48,279,763	47,982,992
Add dilutive effects of stock options and nonvested equity shares of common stock (in shares)	0	0	0	0
Diluted weighted-average common shares outstanding in period (in shares)	48,339,639	48,060,086	48,279,763	47,982,992
Net Income (Loss) Per Common Share, Basic (in dollars per share)	$ (8.49)	$ (0.72)	$ (9.67)	$ (1.54)
Net Income (Loss) Per Common Share, Diluted (in dollars per share)	$ (8.49)	$ (0.72)	$ (9.67)	$ (1.54)

Supplemental Disclosures of C39

Supplemental Disclosures of Cash Flow Information - Supplemental Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Supplemental Cash Flow Information [Abstract]
Cash paid for interest	$ 31,323	$ 36,267
Cash paid for income taxes	1,052	1
Supplemental disclosures of non-cash investing and financing activities:
Accrued liabilities - oil and gas properties	57,699	90,381
Change in asset retirement obligations, net of disposals	(241)	(23,327)
Retirement of treasury stock	(1,100)	(2,462)
Fair Value of Properties Exchanged in Non-Cash Transactions	0	77,078
Relief of Lease Financing Obligation	$ 0	$ (36,106)

Assets Held for Sale (Details)

Assets Held for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	$ 57,300
Oil and gas properties held for sale, net of amortization and impairment	64,882	$ 9,234
Liabilities associated with assets held for sale	$ 7,641	$ 146

Long-Term Debt - Outstanding De

Long-Term Debt - Outstanding Debt (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Mar. 12, 2012	Sep. 27, 2011
Debt Instrument [Line Items]
Principal amount of debt instrument	$ 802,894	$ 803,222
Discount	0	0
Carrying Amount	802,894	803,222
Debt, fair value	$ 549,800	725,800
Amended Credit Facility
Debt Instrument [Line Items]
Maturity Date	Apr. 9, 2020
Principal amount of debt instrument	$ 0	0
Discount	0	0
Carrying Amount	0	0
Debt, fair value	$ 0
Convertible Notes
Debt Instrument [Line Items]
Maturity Date	Mar. 15, 2028
Principal amount of debt instrument	$ 579	25,344
Discount	0	0
Carrying Amount	579	25,344
Aggregate fair value of convertible notes	$ 600	25,100
Debt, stated interest rate	5.00%
Debt, fair value	$ 600	25,100
7.625% Senior Notes
Debt Instrument [Line Items]
Maturity Date	Oct. 1, 2019
Principal amount of debt instrument	$ 400,000	400,000		$ 400,000
Discount	0	0
Carrying Amount	$ 400,000	$ 400,000
Debt, stated interest rate	7.625%	7.625%
Debt, fair value	$ 292,800	$ 359,800
7.0% Senior Notes
Debt Instrument [Line Items]
Maturity Date	Oct. 15, 2022
Principal amount of debt instrument	$ 400,000	400,000	$ 400,000
Discount	0	0
Carrying Amount	$ 400,000	$ 400,000
Debt, stated interest rate	7.00%	7.00%
Debt, fair value	$ 257,000	$ 366,000
Lease Financing Obligation
Debt Instrument [Line Items]
Maturity Date	Aug. 10, 2020
Principal amount of debt instrument	$ 3,330	3,648
Discount	0	0
Carrying Amount	3,330	3,648
Debt, fair value	3,200	3,500
Long-term Debt
Debt Instrument [Line Items]
Principal amount of debt instrument	803,909	828,992
Discount	0	0
Carrying Amount	803,909	828,992
Current Portion of Long-Term Debt
Debt Instrument [Line Items]
Principal amount of debt instrument	1,015	25,770
Discount	0	0
Carrying Amount	$ 1,015	$ 25,770

Long-Term Debt Long-Term Debt -

Long-Term Debt Long-Term Debt - Additional Information (Detail)	Sep. 27, 2011USD ($)	Mar. 20, 2015USD ($)	Mar. 20, 2012USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2014USD ($)	Sep. 30, 2015USD ($)Lenders	Sep. 30, 2014USD ($)	Dec. 31, 2014USD ($)	Mar. 12, 2012USD ($)	Mar. 12, 2008USD ($)
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 375,000,000		$ 375,000,000
Number of Lenders, Credit Facility | Lenders						13
Average annual interest rates incurred on Amended Credit Facility					2.00%		1.90%
Line of credit facility, remaining borrowing capacity				349,000,000		$ 349,000,000
Principal amount				802,894,000		802,894,000		$ 803,222,000
Gain (Loss) on extinguishment of debt				0	$ 0	1,749,000	$ 0
Purchase of equipment				1,800,000		$ 1,800,000
Amended Credit Facility
Debt Instrument [Line Items]
Debt instrument, maturity date						Apr. 9, 2020
Letters of credit issued amount				26,000,000		$ 26,000,000
Principal amount				$ 0		$ 0		0
5% Convertible Senior Notes
Debt Instrument [Line Items]
Principal amount										$ 172,500,000
Face Amount of Outstanding Convertible Notes Repaid		$ 24,800,000	$ 147,200,000
Percentage of notes put to company		98.00%	85.00%
Debt, stated interest rate				5.00%		5.00%
Convertible Debt [Member]
Debt Instrument [Line Items]
Gain (Loss) on extinguishment of debt						$ 2,600,000
Convertible Notes
Debt Instrument [Line Items]
Debt instrument, maturity date						Mar. 15, 2028
Principal amount				$ 579,000		$ 579,000		25,344,000
Debt, stated interest rate				5.00%		5.00%
Debt instrument conversion price rate of redemption						100.00%
Minimum days notice to call Convertible Notes						30 days
7.625% Senior Notes
Debt Instrument [Line Items]
Debt instrument, maturity date						Oct. 1, 2019
Principal amount	$ 400,000,000			$ 400,000,000		$ 400,000,000		$ 400,000,000
Debt, stated interest rate				7.625%		7.625%		7.625%
Par value of senior notes	103.813%
7.0% Senior Notes
Debt Instrument [Line Items]
Debt instrument, maturity date						Oct. 15, 2022
Principal amount				$ 400,000,000		$ 400,000,000		$ 400,000,000	$ 400,000,000
Debt, stated interest rate				7.00%		7.00%		7.00%
Par value of senior notes						103.50%
Lease Financing Obligation
Debt Instrument [Line Items]
Debt instrument, maturity date						Aug. 10, 2020
Principal amount				$ 3,330,000		$ 3,330,000		$ 3,648,000
Weighted average implicit rate based on interest expense				3.30%		3.30%
Minimum
Debt Instrument [Line Items]
Revolving credit facility, interest rate above London Interbank Offered Rate						1.50%
Revolving credit facility interest rate percent above LIBOR alternate interest rate						0.50%
Commitment fee percentage				0.375%		0.375%
Maximum
Debt Instrument [Line Items]
Revolving credit facility, interest rate above London Interbank Offered Rate						2.50%
Revolving credit facility interest rate percent above LIBOR alternate interest rate						1.50%
Commitment fee percentage				0.50%		0.50%
Line of Credit [Member]
Debt Instrument [Line Items]
Interest Expense, Debt						$ 1,600,000
Gain (Loss) on extinguishment of debt						$ (800,000)

Long-Term Debt - Cash and Non-C

Long-Term Debt - Cash and Non-Cash Portion of Interest Expense Related to Long Term Debt (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Mar. 12, 2012	Sep. 27, 2011
Debt Instrument [Line Items]
Principal amount of debt instrument	$ 802,894		$ 802,894		$ 803,222
Cash interest [Member]
Debt Instrument [Line Items]
Amended Credit Facility interest	443	$ 1,771	1,313	$ 4,392
Non-cash interest [Member]
Debt Instrument [Line Items]
Amended Credit Facility interest	$ 165	586	$ 2,534	1,757
Convertible Notes
Debt Instrument [Line Items]
Debt, stated interest rate	5.00%		5.00%
Effective interest rate of debt instrument	5.00%		5.00%
Principal amount of debt instrument	$ 579		$ 579		$ 25,344
Convertible Notes | Cash interest [Member]
Debt Instrument [Line Items]
Convertible Notes interest	22	306	308	940
Convertible Notes | Non-cash interest [Member]
Debt Instrument [Line Items]
Convertible Notes interest	$ 1	1	$ 6	4
7.625% Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate	7.625%		7.625%		7.625%
Effective interest rate of debt instrument	8.00%		8.00%
Principal amount of debt instrument	$ 400,000		$ 400,000		$ 400,000		$ 400,000
7.625% Senior Notes | Cash interest [Member]
Debt Instrument [Line Items]
Senior Notes interest	7,625	7,625	22,875	22,875
7.625% Senior Notes | Non-cash interest [Member]
Debt Instrument [Line Items]
Senior Notes interest	$ 267	273	$ 813	817
7.0% Senior Notes
Debt Instrument [Line Items]
Debt, stated interest rate	7.00%		7.00%		7.00%
Effective interest rate of debt instrument	7.20%		7.20%
Principal amount of debt instrument	$ 400,000		$ 400,000		$ 400,000	$ 400,000
7.0% Senior Notes | Cash interest [Member]
Debt Instrument [Line Items]
Senior Notes interest	7,000	7,000	21,000	21,000
7.0% Senior Notes | Non-cash interest [Member]
Debt Instrument [Line Items]
Senior Notes interest	$ 199	204	$ 607	610
Lease Financing Obligation
Debt Instrument [Line Items]
Effective interest rate of debt instrument	3.30%		3.30%
Principal amount of debt instrument	$ 3,330		$ 3,330		$ 3,648
Lease Financing Obligation | Cash interest [Member]
Debt Instrument [Line Items]
Financial Obligation interest	27	248	84	765
Lease Financing Obligation | Non-cash interest [Member]
Debt Instrument [Line Items]
Financial Obligation interest	$ 0	$ 3	$ 24	$ 11

Asset Retirement Obligations -

Asset Retirement Obligations - Schedule of Asset Retirement Obligations (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2015USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
As of December 31, 2014	$ 22,852
Liabilities incurred	754
Liabilities settled	(162)
Disposition of properties	(745)
Accretion expense	1,091
Revisions to estimate	(88)
As of September 30, 2015	23,702
Less: liabilities associated with assets held for sale	7,641
Less: current asset retirement obligations	1,362
Long-term asset retirement obligations	$ 14,699

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value, Balance Sheet Grouping (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Assets
Cash Equivalents	$ 92,836	$ 165,904	$ 294,778	$ 54,595
Commodity Derivatives	142,056	194,976
Liabilities
Commodity Derivatives		0
Total
Assets
Deferred Compensation Plan	1,080	1,069
Cash Equivalents	40,054	75,066
Commodity Derivatives	142,056	195,176
Liabilities
Commodity Derivatives		200
Level 1
Assets
Deferred Compensation Plan	1,080	1,069
Cash Equivalents	40,054	75,066
Commodity Derivatives	0	0
Liabilities
Commodity Derivatives		0
Level 2
Assets
Deferred Compensation Plan	0	0
Cash Equivalents	0	0
Commodity Derivatives	142,056	195,176
Liabilities
Commodity Derivatives		200
Level 3
Assets
Deferred Compensation Plan	0	0
Cash Equivalents	0	0
Commodity Derivatives	$ 0	0
Liabilities
Commodity Derivatives		$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Fair Value Measurements [Line Items]
Debt, fair value	$ 549,800	$ 725,800
Assets, Fair Value Disclosure, Nonrecurring	180,000
Impairment of Oil and Gas Properties	571,900	39,800
Assets held for sale	$ 64,882	9,234
Powder River Basin [Member]
Fair Value Measurements [Line Items]
Impairment of Oil and Gas Properties		$ 21,100
7.625% Senior Notes
Fair Value Measurements [Line Items]
Debt, stated interest rate	7.625%	7.625%
Debt, fair value	$ 292,800	$ 359,800
7.0% Senior Notes
Fair Value Measurements [Line Items]
Debt, stated interest rate	7.00%	7.00%
Debt, fair value	$ 257,000	$ 366,000
Amended Credit Facility
Fair Value Measurements [Line Items]
Debt, fair value	$ 0
Convertible Notes
Fair Value Measurements [Line Items]
Debt, stated interest rate	5.00%
Debt, fair value	$ 600	25,100
Lease Financing Obligation
Fair Value Measurements [Line Items]
Debt, fair value	$ 3,200	$ 3,500

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurements, Nonrecurring (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Capitalized Costs, Oil and Gas Producing Activities, Net	$ 1,226,319	$ 1,739,406
Assets Held-for-sale, Long Lived, Fair Value Disclosure	57,300
Proved Oil And Gas Properties [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Oil and Gas Properties Held for Sale, Net of DD&A	50,300	6,700
Proved Oil And Gas Properties [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Capitalized Costs, Oil and Gas Producing Activities, Net	225,363	1,588,038
Proved Oil And Gas Properties [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0
Impairment of Assets Held For Sale, Long Lived, Fair Value Disclosure		0
Proved Oil And Gas Properties [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0
Impairment of Assets Held For Sale, Long Lived, Fair Value Disclosure		0
Proved Oil And Gas Properties [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	225,363
Impairment of Assets Held For Sale, Long Lived, Fair Value Disclosure		15,761
Unproved Oil And Gas Properties [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Oil and Gas Properties Held for Sale, Net of DD&A	14,600	2,500
Unproved Oil And Gas Properties [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Capitalized Costs, Oil and Gas Producing Activities, Net	19,519	151,368
Unproved Oil And Gas Properties [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0
Impairment of Assets Held For Sale, Long Lived, Fair Value Disclosure		0
Unproved Oil And Gas Properties [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	0
Impairment of Assets Held For Sale, Long Lived, Fair Value Disclosure		0
Unproved Oil And Gas Properties [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets Held-for-sale, Long Lived, Fair Value Disclosure	$ 19,519
Impairment of Assets Held For Sale, Long Lived, Fair Value Disclosure		$ 24,082

Derivative Instruments - Fair V

Derivative Instruments - Fair Value Amounts of Derivative Instruments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Derivative Assets	$ 142,056	$ 195,176
Gross Amounts Offset in the Balance Sheet	0	(200)
Net Amounts of Derivative Assets Presented in the Balance Sheet	142,056	194,976
Gross Amounts of Recognized Derivative Liabilities		(200)
Gross Amounts Offset in the Balance Sheet		200
Net Amounts of Derivative Liabilities Presented in the Balance Sheet		0
Derivative assets (current)
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Derivative Assets	109,847	145,426
Gross Amounts Offset in the Balance Sheet	0	(200)
Net Amounts of Derivative Assets Presented in the Balance Sheet	109,847	145,226
Derivative assets (noncurrent)
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Derivative Assets	32,209	49,750
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Derivative Assets Presented in the Balance Sheet	$ 32,209	49,750
Derivative liabilities
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Derivative Liabilities		(200)
Gross Amounts Offset in the Balance Sheet		200
Net Amounts of Derivative Liabilities Presented in the Balance Sheet		$ 0

Derivative Instruments - Financ

Derivative Instruments - Financial Instruments for Hedging Volume (Detail)	Sep. 30, 2015USD ($)MMBTUbbl
October – December 2015
Derivative Instruments, Gain (Loss) [Line Items]
Oil (Bbls) | bbl	993,600
Weighted Average Price, Hedge Backed Oil Volumes	$ 89.81
Natural Gas (MMbtu) | MMBTU	1,840,000
Weighted Average Price, Hedge Backed Gas Volumes	$ 4.13
For the year 2016
Derivative Instruments, Gain (Loss) [Line Items]
Oil (Bbls) | bbl	2,478,600
Weighted Average Price, Hedge Backed Oil Volumes	$ 80.47
Natural Gas (MMbtu) | MMBTU	1,830,000
Weighted Average Price, Hedge Backed Gas Volumes	$ 4.10
For the year 2017
Derivative Instruments, Gain (Loss) [Line Items]
Oil (Bbls) | bbl	683,250
Weighted Average Price, Hedge Backed Oil Volumes	$ 75.61
Natural Gas (MMbtu) | MMBTU	0
Weighted Average Price, Hedge Backed Gas Volumes	$ 0

Derivative Instruments - Realiz

Derivative Instruments - Realized and Unrealized Gains and Losses on Commodity Derivative Instruments (Detail) - Oil and Natural Gas Derivative Instruments - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Commodity derivative gain settlements on derivatives designated as cash flow hedges	$ 0	$ 351	$ 0	$ 889
Total commodity derivative gain (loss)	$ 69,133	$ 72,299	$ 75,914	$ 369

Derivative Instruments - Additi

Derivative Instruments - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015Counterparty
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Number of counterparties for hedges at period end	8

Income Taxes Income Taxes (Deta

Income Taxes Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Non-cash impairment of oil and gas properties	$ 571.9	$ 39.8
Deferred Tax Assets, Valuation Allowance	$ 66.4

Equity Incentive Compensation53

Equity Incentive Compensation Plans and Other Long-term Incentive Programs - Non-Cash Stock-Based Compensation Cost Related to Equity Awards (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Stock Based Compensation [Line Items]
Non-cash stock-based compensation equity awards	$ 2,153	$ 3,471	$ 7,217	$ 9,289
Common Stock Options
Stock Based Compensation [Line Items]
Non-cash stock-based compensation equity awards	137	482	528	1,608
Nonvested Equity Common Stock
Stock Based Compensation [Line Items]
Non-cash stock-based compensation equity awards	1,816	1,760	5,007	4,979
Nonvested Equity Common Stock Units
Stock Based Compensation [Line Items]
Non-cash stock-based compensation equity awards	250	274	779	783
Nonvested Performance-Based Equity
Stock Based Compensation [Line Items]
Non-cash stock-based compensation equity awards	$ (50)	$ 955	$ 903	$ 1,919

Equity Incentive Compensation54

Equity Incentive Compensation Plans and Other Long-term Incentive Programs - Additional Information (Detail) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015USD ($)unit	Sep. 30, 2015USD ($)unit
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Unrecognized compensation cost	$ 16.5	$ 16.5
Weighted-average period (years)		2 years 1 month 6 days
2015 Performance Program
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Weighted Percentage Of Stockholders Return Related To Performance Goals		60.00%
Performance Goals Percentage for Change In Discretionary Cash Flow Per Debt Adjusted Share Relative To Defined Peer Groups Percentage		40.00%
Maximum Number Of Cash Units Vest As Percentage Of Performance Cash Units Granted		200.00%
Number Of Performance Cash Units Granted | unit	409,046	409,046
Deferred Compensation Cash-based Arrangements, Liability, Current and Noncurrent	$ 0.3	$ 0.3
Deferred Compensation Arrangement with Individual, Compensation Expense	$ (0.1)	$ 0.3
2015 Performance Program | Minimum [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage Of Grant That Will Vest For Performance Met At Threshold Level	25.00%	25.00%
2015 Performance Program | Maximum
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Percentage Of Grant That Will Vest For Performance Met At Threshold Level	50.00%	50.00%
Percentage of total grant that will vest for metrics met at target level	100.00%	100.00%
Percentage of total grant that will vest for metrics met at stretch level		200.00%

Equity Incentive Compensation55

Equity Incentive Compensation Plans and Other Long-term Incentive Programs - Stock Options and Nonvested Equity Shares, Equity Awards Granted (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Nonvested equity shares, Number of Shares	32,618	26,828	664,757	516,768
Nonvested equity common stock units, Number of Shares	5,681	850	130,669	44,282
Nonvested performance-based equity shares, Number of Shares	0	10,073	0	303,188
Total shares granted	38,299	37,751	795,426	864,238
Nonvested equity shares, Weighted Average Grant Date Fair Value	$ 5.24	$ 21.53	$ 11.91	$ 22.49
Nonvested equity common stock units, Weighted Average Grant Date Fair Value	3.30	22.04	8.47	24.98
Nonvested performance-based equity shares, Weighted Average Grant Date Fair Value	$ 0	$ 18.52	$ 0	$ 19.77

Equity Distribution Agreement (

Equity Distribution Agreement (Details) - USD ($) $ in Millions	Jun. 10, 2015	Sep. 30, 2015
Equity Distribution Agreement [Abstract]
Maximum Aggregate Offering Price	$ 100
Number of Shares Sold, Equity Distribution Agreement		0

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Aggregate Undiscounted Minimum Future Lease Payments (Detail) - Lease Financing Obligation $ in Thousands	Sep. 30, 2015USD ($)
Future Minimum Lease Payments Under Capital Leases And Operating Leases For Continuing Operations [Line Items]
2,015	$ 135
2,016	537
2,017	537
2,018	537
2,019	1,825
Thereafter	0
Total	$ 3,571

Commitments and Contingencies58

Commitments and Contingencies - Additional Information (Detail) MMcf in Millions, $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2015USD ($)MMcf	Sep. 30, 2015USD ($)AgreementMMcf
Contingencies And Commitments [Line Items]
Drilling Commitment	$ 1.3	$ 1.3
Number of Firm Transportation Contracts | Agreement		2
Number of take-or-pay purchase agreements for supply of carbon dioxide | Agreement		1
Total financial commitment on take-or-pay purchase agreements for supply of carbon dioxide		$ 1.5
Maximum
Contingencies And Commitments [Line Items]
Contract term, years	6 years
Commitment Ending November 30, 2015 [Member]
Contingencies And Commitments [Line Items]
Minimum Volume Commitment | MMcf	450	450
Minimum Volume Commitment Deficiency Payment	$ 0.8	$ 0.8
Minimum Volume Commitment, Volumes Satisfied | MMcf	190.2	190.2
Minimum Volume Commitment, Estimated Deficiency Payment	$ 0.4	$ 0.4

Commitments and Contingencies59

Commitments and Contingencies - Gross Future Minimum Transportation Demand and Firm Processing Charges (Detail) $ in Thousands	Sep. 30, 2015USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,015	$ 4,576
2,016	18,692
2,017	18,692
2,018	18,692
2,019	18,692
Thereafter	29,595
Total	$ 108,939

Commitments and Contingencies60

Commitments and Contingencies - Future Minimum Annual Payments under Drilling, Lease and Other Agreements (Detail) - Office & Equipment Leases $ in Thousands	Sep. 30, 2015USD ($)
Operating Leased Assets [Line Items]
2,015	$ 2,646
2,016	2,995
2,017	2,892
2,018	2,591
2,019	633
Thereafter	0
Total	$ 11,757

Guarantor Subsidiaries - Additi

Guarantor Subsidiaries - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Percentage of Guarantor Subsidiaries	100.00%
7.625% Senior Notes
Condensed Financial Statements, Captions [Line Items]
Debt, stated interest rate	7.625%	7.625%
7.0% Senior Notes
Condensed Financial Statements, Captions [Line Items]
Debt, stated interest rate	7.00%	7.00%

Guarantor Subsidiaries - Schedu

Guarantor Subsidiaries - Schedule of Condensed Consolidating Balance Sheets (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Assets:
Current assets	$ 270,140	$ 426,105
Property and equipment, net	1,238,947	1,753,121
Intercompany receivable (payable)	0	0
Investment in subsidiaries	0	0
Noncurrent assets	87,173	65,258
Total	1,596,260	2,244,484
Liabilities and Stockholders' Equity:
Current liabilities	200,214	264,687
Long-term debt	802,894	803,222
Deferred income taxes	0	122,350
Other noncurrent liabilities	25,386	24,737
Stockholders' equity	567,766	1,029,488	$ 1,005,718
Total liabilities and stockholders' equity	1,596,260	2,244,484
Parent Issuer
Assets:
Current assets	270,062	426,103
Property and equipment, net	1,232,180	1,730,074
Intercompany receivable (payable)	21,416	22,840
Investment in subsidiaries	(14,716)	163
Noncurrent assets	87,173	65,258
Total	1,596,115	2,244,438
Liabilities and Stockholders' Equity:
Current liabilities	200,120	264,687
Long-term debt	802,894	803,222
Deferred income taxes		122,350
Other noncurrent liabilities	25,335	24,691
Stockholders' equity	567,766	1,029,488
Total liabilities and stockholders' equity	1,596,115	2,244,438
Guarantor Subsidiaries
Assets:
Current assets	78	2
Property and equipment, net	6,767	23,047
Intercompany receivable (payable)	(21,416)	(22,840)
Investment in subsidiaries	0	0
Noncurrent assets	0	0
Total	(14,571)	209
Liabilities and Stockholders' Equity:
Current liabilities	94	0
Long-term debt	0	0
Deferred income taxes		0
Other noncurrent liabilities	51	46
Stockholders' equity	(14,716)	163
Total liabilities and stockholders' equity	(14,571)	209
Intercompany Eliminations
Assets:
Current assets	0	0
Property and equipment, net	0	0
Intercompany receivable (payable)	0	0
Investment in subsidiaries	14,716	(163)
Noncurrent assets	0	0
Total	14,716	(163)
Liabilities and Stockholders' Equity:
Current liabilities	0	0
Long-term debt	0	0
Deferred income taxes		0
Other noncurrent liabilities	0	0
Stockholders' equity	14,716	(163)
Total liabilities and stockholders' equity	$ 14,716	$ (163)

Guarantor Subsidiaries - Sche63

Guarantor Subsidiaries - Schedule of Condensed Consolidating Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Operating and other revenues	$ 49,679	$ 135,263	$ 161,331	$ 405,389
Operating expenses	(645,712)	(235,185)	(794,624)	(429,752)
General and administrative	(11,025)	(11,111)	(39,026)	(41,039)
Interest and other income (expense)	53,479	54,530	28,608	(51,925)
Income (loss) before income taxes and equity in earnings (loss) of subsidiaries	(553,579)	(56,503)	(643,711)	(117,327)
(Provision for) Benefit from Income Taxes	143,265	21,854	177,085	43,343
Equity in earnings (loss) of subsidiaries	0	0	0	0
Net Income (Loss)	(410,314)	(34,649)	(466,626)	(73,984)	$ 15,081
Parent Issuer
Condensed Financial Statements, Captions [Line Items]
Operating and other revenues	49,562	135,263	160,963	405,398
Operating expenses	(630,783)	(235,123)	(779,377)	(429,560)
General and administrative	(11,025)	(11,111)	(39,026)	(41,039)
Interest and other income (expense)	53,479	54,530	28,608	(51,960)
Income (loss) before income taxes and equity in earnings (loss) of subsidiaries	(538,767)	(56,441)	(628,832)	(117,161)
(Provision for) Benefit from Income Taxes	143,265	21,854	177,085	43,343
Equity in earnings (loss) of subsidiaries	(14,812)	(62)	(14,879)	(166)
Net Income (Loss)	(410,314)	(34,649)	(466,626)	(73,984)
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Operating and other revenues	117	0	368	(9)
Operating expenses	(14,929)	(62)	(15,247)	(192)
General and administrative	0	0	0	0
Interest and other income (expense)	0	0	0	35
Income (loss) before income taxes and equity in earnings (loss) of subsidiaries	(14,812)	(62)	(14,879)	(166)
(Provision for) Benefit from Income Taxes	0	0	0	0
Equity in earnings (loss) of subsidiaries	0	0	0	0
Net Income (Loss)	(14,812)	(62)	(14,879)	(166)
Intercompany Eliminations
Condensed Financial Statements, Captions [Line Items]
Operating and other revenues	0	0	0	0
Operating expenses	0	0	0	0
General and administrative	0	0	0	0
Interest and other income (expense)	0	0	0	0
Income (loss) before income taxes and equity in earnings (loss) of subsidiaries	0	0	0	0
(Provision for) Benefit from Income Taxes	0	0	0	0
Equity in earnings (loss) of subsidiaries	14,812	62	14,879	166
Net Income (Loss)	$ 14,812	$ 62	$ 14,879	$ 166

Guarantor Subsidiaries - Sche64

Guarantor Subsidiaries - Schedule of Condensed Consolidating Statements of Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ (410,314)	$ (34,649)	$ (466,626)	$ (73,984)	$ 15,081
Effect of derivative financial instruments	0	(219)	0	(555)	$ (669)
Other comprehensive income (loss)	0	(219)	0	(555)
Comprehensive Income (Loss)	(410,314)	(34,868)	(466,626)	(74,539)
Parent Issuer
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(410,314)	(34,649)	(466,626)	(73,984)
Effect of derivative financial instruments	0	(219)	0	(555)
Other comprehensive income (loss)	0	(219)	0	(555)
Comprehensive Income (Loss)	(410,314)	(34,868)	(466,626)	(74,539)
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(14,812)	(62)	(14,879)	(166)
Effect of derivative financial instruments	0	0	0	0
Other comprehensive income (loss)	0	0	0	0
Comprehensive Income (Loss)	(14,812)	(62)	(14,879)	(166)
Intercompany Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	14,812	62	14,879	166
Effect of derivative financial instruments	0	0	0	0
Other comprehensive income (loss)	0	0	0	0
Comprehensive Income (Loss)	$ 14,812	$ 62	$ 14,879	$ 166

Guarantor Subsidiaries - Sche65

Guarantor Subsidiaries - Schedule of Condensed Consolidating Statements of Cash Flows (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	$ 165,901	$ 231,302
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions	(256,059)	(425,978)
Additions to furniture, fixtures and other	(1,036)	(2,110)
Proceeds from sale of properties and other investing activities	66,617	557,747
Cash paid for short-term investments	(114,883)	0
Proceeds from the sale of short-term investments	95,000	0
Intercompany Transfers Investing Activities	0	0
Cash flows from financing activities:
Proceeds from debt	0	165,000
Principal payments on debt	(25,083)	(283,442)
Intercompany Transfer Financing Activities	0	0
Other financing activities	(3,525)	(2,336)
Increase (Decrease) in Cash and Cash Equivalents	(73,068)	240,183
Beginning Cash and Cash Equivalents	165,904	54,595
Ending Cash and Cash Equivalents	92,836	294,778
Parent Issuer
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	165,911	231,274
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions	(257,399)	(419,268)
Additions to furniture, fixtures and other	(1,036)	(2,110)
Proceeds from sale of properties and other investing activities	66,617	555,926
Cash paid for short-term investments	(114,883)
Proceeds from the sale of short-term investments	95,000
Intercompany Transfers Investing Activities	1,330	(4,861)
Cash flows from financing activities:
Proceeds from debt	0	165,000
Principal payments on debt	(25,083)	(283,442)
Intercompany Transfer Financing Activities	0	0
Other financing activities	(3,525)	(2,336)
Increase (Decrease) in Cash and Cash Equivalents	(73,068)	240,183
Beginning Cash and Cash Equivalents	165,904	54,595
Ending Cash and Cash Equivalents	92,836	294,778
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	(10)	28
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions	1,340	(6,710)
Additions to furniture, fixtures and other	0	0
Proceeds from sale of properties and other investing activities	0	1,821
Cash paid for short-term investments	0
Proceeds from the sale of short-term investments	0
Intercompany Transfers Investing Activities	0	0
Cash flows from financing activities:
Proceeds from debt	0	0
Principal payments on debt	0	0
Intercompany Transfer Financing Activities	(1,330)	4,861
Other financing activities	0	0
Increase (Decrease) in Cash and Cash Equivalents	0	0
Beginning Cash and Cash Equivalents	0	0
Ending Cash and Cash Equivalents	0	0
Intercompany Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	0	0
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions	0	0
Additions to furniture, fixtures and other	0	0
Proceeds from sale of properties and other investing activities	0	0
Cash paid for short-term investments	0
Proceeds from the sale of short-term investments	0
Intercompany Transfers Investing Activities	(1,330)	4,861
Cash flows from financing activities:
Proceeds from debt	0	0
Principal payments on debt	0	0
Intercompany Transfer Financing Activities	1,330	(4,861)
Other financing activities	0	0
Increase (Decrease) in Cash and Cash Equivalents	0	0
Beginning Cash and Cash Equivalents	0	0
Ending Cash and Cash Equivalents	$ 0	$ 0

Subsequent Events (Details)

Subsequent Events (Details) $ in Millions	Oct. 21, 2015USD ($)
Subsequent Event [Member]
Subsequent Event [Line Items]
Consideration for Non-core Assets	$ 23