Bill Barrett (BBG) 10-Q 31 Jul 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Jul. 18, 2014
Document Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Trading Symbol	'BBG	'
Entity Registrant Name	'BILL BARRETT CORPORATION	'
Entity Central Index Key	'0001172139	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	49,637,237

CONSOLIDATED_BALANCE_SHEETS_UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$55,779	$54,595
Accounts receivable, net of allowance for doubtful accounts	91,880	97,586
Deferred income taxes	14,926	0
Derivative assets	0	173
Prepayments and other current assets	3,396	4,893
Total current assets	165,981	157,247
Property and equipment - at cost, successful efforts method for oil and gas properties:	'	'
Proved oil and gas properties	3,107,305	2,863,923
Unproved oil and gas properties, excluded from amortization	299,472	296,599
Furniture, equipment and other	42,432	41,726
Property, plant and equipment, gross	3,449,209	3,202,248
Accumulated depreciation, depletion, amortization and impairment	-1,098,253	-999,752
Total property and equipment, net	2,350,956	2,202,496
Deferred financing costs and other noncurrent assets	17,375	21,770
Total	2,534,312	2,381,513
Current liabilities:	'	'
Accounts payable and accrued liabilities	124,293	115,928
Amounts payable to oil and gas property owners	29,028	26,778
Production taxes payable	38,584	39,235
Derivative liabilities	41,379	5,988
Deferred income taxes	0	199
Current portion of long-term debt	4,685	4,591
Total current liabilities	237,969	192,719
Long-term debt	1,111,703	979,082
Asset retirement obligations	40,443	39,200
Deferred income taxes	154,718	161,326
Derivatives and other noncurrent liabilities	18,884	3,468
Stockholders' equity:	'	'
Common stock, $0.001 par value; authorized 150,000,000 shares; 49,648,285 and 49,152,448 shares issued and outstanding at June 30, 2014 and December 31, 2013, respectively, with 1,621,640 and 1,340,060 shares subject to restrictions, respectively	48	48
Additional paid-in capital	908,809	904,261
Retained earnings	61,405	100,740
Treasury stock, at cost: zero shares at June 30, 2014 and December 31, 2013, respectively	0	0
Accumulated other comprehensive income	333	669
Total stockholders' equity	970,595	1,005,718
Total liabilities and stockholders' equity	$2,534,312	$2,381,513

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]	'	'
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	49,648,285	49,152,448
Common stock, shares outstanding	49,648,285	49,152,448
Common stock, shares subject to restrictions	1,621,640	1,340,060
Treasury stock, shares	0	0

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Operating and Other Revenues:	'	'	'	'
Oil, gas and NGL production	$136,220	$140,380	$263,389	$274,785
Other	8,788	1,919	9,307	5,791
Total operating and other revenues	145,008	142,299	272,696	280,576
Operating Expenses:	'	'	'	'
Lease operating expense	15,919	16,112	32,083	34,858
Gathering, transportation and processing expense	11,750	18,772	23,454	34,360
Production tax expense	9,651	7,781	17,275	13,732
Exploration expense	116	141	419	236
Impairment, dry hole costs and abandonment expense	1,743	1,182	3,504	8,283
Depreciation, depletion and amortization	64,894	74,307	120,402	142,745
General and administrative expense	14,521	13,273	29,928	33,855
Total operating expenses	118,594	131,568	227,065	268,069
Operating Income	26,414	10,731	45,631	12,507
Other Income and Expense:	'	'	'	'
Interest and other income	352	32	727	71
Interest expense	-17,821	-24,726	-35,252	-49,268
Commodity derivative gain (loss)	-46,775	36,839	-71,930	6,988
Total other income and expense	-64,244	12,145	-106,455	-42,209
Income (Loss) before Income Taxes	-37,830	22,876	-60,824	-29,702
Provision for (Benefit from) Income Taxes	-11,244	8,603	-21,489	-10,824
Net Income (Loss)	($26,586)	$14,273	($39,335)	($18,878)
Net Income (Loss) Per Common Share, Basic (in dollars per share)	($0.55)	$0.30	($0.82)	($0.40)
Net Income (Loss) Per Common Share, Diluted (in dollars per share)	($0.55)	$0.30	($0.82)	($0.40)
Weighted Average Common Shares Outstanding, Basic	47,996,816	47,468,569	47,943,806	47,411,054
Weighted Average Common Shares Outstanding, Diluted	47,996,816	47,615,871	47,943,806	47,411,054

CONSOLIDATED_STATEMENTS_OF_COM

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'	'
Net Income (Loss)	($26,586)	$14,273	($39,335)	($18,878)	($192,733)
Other Comprehensive Loss, net of tax:	'	'	'	'	'
Effect of derivative financial instruments	-239	-1,210	-336	-2,502	-4,663
Other comprehensive loss	-239	-1,210	-336	-2,502	'
Comprehensive Income (Loss)	($26,825)	$13,063	($39,671)	($21,380)	'

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Operating Activities:	'	'
Net Income (Loss)	($39,335)	($18,878)
Adjustments to reconcile to net cash provided by operations:	'	'
Depreciation, depletion and amortization	120,402	142,745
Deferred income tax benefit	-21,531	-10,824
Impairment, dry hole costs and abandonment expense	3,504	8,283
Total commodity derivative (gain) loss	71,930	-6,988
Settlements of commodity derivatives	-18,526	6,226
Stock compensation and other non-cash charges	6,155	9,289
Amortization of debt discounts and deferred financing costs	2,132	3,466
Gain on sale of properties	-2,570	-4,193
Change in operating assets and liabilities:	'	'
Accounts receivable	5,699	16,506
Prepayments and other assets	1,068	1,585
Accounts payable, accrued and other liabilities	-2,795	-23,743
Amounts payable to oil and gas property owners	1,936	9,737
Production taxes payable	-651	-10,182
Net cash provided by operating activities	127,418	123,029
Investing Activities:	'	'
Additions to oil and gas properties, including acquisitions	-264,345	-216,652
Additions of furniture, equipment and other	-856	-1,187
Proceeds from sale of properties and other investing activities	8,175	4,086
Net cash used in investing activities	-257,026	-213,753
Financing Activities:	'	'
Proceeds from debt	135,000	80,000
Principal payments on debt	-2,285	-4,501
Proceeds from stock option exercises	126	3
Deferred financing costs and other	-2,049	-1,348
Net cash provided by financing activities	130,792	74,154
Increase (Decrease) in Cash and Cash Equivalents	1,184	-16,570
Beginning Cash and Cash Equivalents	54,595	79,445
Ending Cash and Cash Equivalents	$55,779	$62,875

CONSOLIDATED_STATEMENTS_OF_STO

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (UNAUDITED) (USD $)	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income
In Thousands, unless otherwise specified
Balance at Dec. 31, 2012	$1,182,775	$47	$883,923	$293,473	'	$5,332
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Exercise of options, restricted stock activity and shares exchanged for exercise and tax withholding	4,607	1	6,384	'	-1,778	'
APIC pool for excess tax benefits related to share-based compensation	-1,259	'	-1,259	'	'	'
Stock-based compensation	16,991	'	16,991	'	'	'
Retirement of treasury stock	'	'	-1,778	'	1,778	'
Net income (loss)	-192,733	'	'	-192,733	'	'
Effect of derivative financial instruments, net of taxes	-4,663	'	'	'	'	-4,663
Balance at Dec. 31, 2013	1,005,718	48	904,261	100,740	'	669
Increase (Decrease) in Stockholders' Equity [Roll Forward]	'	'	'	'	'	'
Exercise of options, restricted stock activity and shares exchanged for exercise and tax withholding	-1,923	'	126	'	-2,049	'
Stock-based compensation	6,471	'	6,471	'	'	'
Retirement of treasury stock	'	'	-2,049	'	2,049	'
Net income (loss)	-39,335	'	'	-39,335	'	'
Effect of derivative financial instruments, net of taxes	-336	'	'	'	'	-336
Balance at Jun. 30, 2014	$970,595	$48	$908,809	$61,405	'	$333

CONSOLIDATED_STATEMENTS_OF_STO1

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) (USD $)	6 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Statement of Stockholders' Equity [Abstract]	'	'
Effect of derivative financial instruments, taxes	$202	$2,802

Organization

Organization	6 Months Ended
	Jun. 30, 2014
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_Account

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2014
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 2013 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 the expected cash settlement of the Company's 5% Convertible Senior Notes due 2028 ("Convertible Notes") in computing diluted earnings per share, 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 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 undeveloped properties, valuing deferred tax assets and estimating fair values of derivative instruments and stock-based compensation awards.
	Accounts Receivable. Accounts receivable is comprised of the following:
		As of June 30, 2014			As of December 31, 2013
		(in thousands)
	Accrued oil, gas and NGL sales	$	61,381		$	67,583
	Due from joint interest owners	23,890			23,507
	Other	6,630			6,517
	Allowance for doubtful accounts	(21		)	(21		)
	Total accounts receivable	$	91,880		$	97,586
	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 when incurred. The costs of development wells are capitalized whether proved reserves are added or not. Oil and gas lease acquisition costs are also capitalized.
	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. A gain or loss is recognized for all other sales of proved properties and is classified in other operating revenues. 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 June 30, 2014			As of December 31, 2013
		(in thousands)
	Proved properties	$	494,371		$	485,427
	Wells and related equipment and facilities	2,421,552			2,192,754
	Support equipment and facilities	180,421			177,224
	Materials and supplies	10,961			8,518
	Total proved oil and gas properties	$	3,107,305		$	2,863,923
	Unproved properties	212,623			239,925
	Wells and facilities in progress	86,849			56,674
	Total unproved oil and gas properties, excluded from amortization	$	299,472		$	296,599
	Accumulated depreciation, depletion, amortization and impairment	(1,072,804		)	(976,339		)
	Total oil and gas properties, net	$	2,333,973		$	2,184,183
	All exploratory wells are evaluated for economic viability within one year of well completion. Exploratory wells that discover potentially economic reserves in areas where a major capital expenditure would be required before production could begin, and where the economic viability of that major capital expenditure depends upon the successful completion of further exploratory work in the area, remain capitalized if the well finds a sufficient quantity of reserves to justify its completion as a producing well and the Company is making sufficient progress assessing the reserves and the economic and operating viability of the project. As of June 30, 2014 and December 31, 2013, there were no exploratory well costs that had been capitalized for a period greater than one year since the completion of drilling.
	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 cash flows of its oil and gas properties and compares such undiscounted future cash flows to the carrying amount of the oil and gas properties to determine if the carrying amount is recoverable. If the carrying value of a property exceeds the undiscounted future cash flows, the Company will impair the carrying value to fair value based on an analysis of quantitative and qualitative factors. The Company has no guarantee that the undiscounted future 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, 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 expected cash flows projected.
	The Company recognized non-cash impairment charges, which were included within impairment, dry hole costs and abandonment expense in the Unaudited Consolidated Statements of Operations, as follows:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
		(in thousands)
	Non-cash impairment of proved oil and gas properties (1)	$	—		$	—		$	1,038		$	—
	Non-cash impairment of unproved oil and gas properties	—			—			—			—
	Non-cash impairment of inventory (2)	340			—			340			—
	Dry hole costs	(12		)	113			94			964
	Abandonment expense	1,415			1,069			2,032			7,319
	Total non-cash impairment, dry hole costs and abandonment expense	$	1,743		$	1,182		$	3,504		$	8,283
	-1	Non-cash impairment of proved oil and gas properties for the six months ended June 30, 2014 related to the Company's West Tavaputs properties based upon a true up of previously estimated fair value relative to carrying value. These assets were sold in December 2013. See Note 4.
	-2	Non-cash impairment of inventory related to impairing unused oil and gas related equipment to fair value.
	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 June 30, 2014			As of December 31, 2013
		(in thousands)
	Accrued drilling, completion and facility costs	$	80,132		$	54,750
	Accrued lease operating, gathering, transportation and processing expenses	12,791			17,317
	Accrued general and administrative expenses	8,504			14,605
	Trade payables and other	22,866			29,256
	Total accounts payable and accrued liabilities	$	124,293		$	115,928
	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 and gas 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' 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 June 30, 2014 and 2013 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.
	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.
	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.
	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 months and six months ended June 30, 2014 and the six months ended June 30, 2013.
	In satisfaction of its obligation upon conversion of the Convertible Notes, the Company may elect to deliver, at its option, cash, shares of its common stock or a combination of cash and shares of its common stock. As of June 30, 2014, the Company expected to settle the remaining Convertible Notes in cash. Therefore, the treasury stock method was used to measure the potentially dilutive impact of shares associated with that remaining conversion feature. The Company has the right with at least 30 days' notice to call the Convertible Notes and the holders have the right to require the Company to purchase the notes on March 20, 2015. The Convertible Notes have not been dilutive since their issuance in March 2008 and, therefore, did not impact the diluted net income (loss) per common share calculation for the three and six months ended June 30, 2014 and 2013. The diluted net income (loss) per common share excludes the anti-dilutive effect of 1,120,210 and 2,857,757 shares of stock options and nonvested performance-based shares of common stock for the three months ended June 30, 2014 and 2013, and 1,257,716 and 2,836,480 shares of stock options and nonvested performance-based shares of common stock for the six months ended June 30, 2014 and 2013, respectively.
	The following table sets forth the calculation of basic and diluted earnings (loss) per share:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
		(in thousands, except per share amounts)
Net income (loss)	$	(26,586	)	$	14,273		$	(39,335	)	$	(18,878	)
Basic weighted-average common shares outstanding in period	47,997			47,469			47,944			47,411
Add dilutive effects of stock options and nonvested equity shares of common stock	—			147			—			—
Diluted weighted-average common shares outstanding in period	47,997			47,616			47,944			47,411
Basic net income (loss) per common share	$	(0.55	)	$	0.3		$	(0.82	)	$	(0.40	)
Diluted net income (loss) per common share	$	(0.55	)	$	0.3		$	(0.82	)	$	(0.40	)
New Accounting Pronouncements. 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. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. The Company is currently evaluating the potential impact that the adoption will have on the Company’s disclosures and financial statements.
In June 2014, the FASB issued ASU 2014-12, Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period. The objective of this update is to provide guidance on the treatment of a performance target that could be achieved after the requisite service period. ASU 2014-12 is effective for annual periods and interim periods within those annual periods beginning after December 15, 2015. The adoption of this standard will not have an impact on the Company's consolidated financial statements.

Supplemental_Disclosures_of_Ca

Supplemental Disclosures of Cash Flow Information	6 Months Ended
	Jun. 30, 2014
Supplemental Cash Flow Elements [Abstract]	'
Supplemental Disclosures of Cash Flow Information	'
	Supplemental Disclosures of Cash Flow Information
	Supplemental cash flow information is as follows:
		Six Months Ended June 30,
		2014			2013
		(in thousands)
	Cash paid for interest, net of amount capitalized	$	33,173		$	45,709
	Cash paid for income taxes	1			1,861
	Supplemental disclosures of non-cash investing and financing activities:
	Current liabilities	82,782			68,731
	Net increase in asset retirement obligations	3,195			1,888
	Retirement of treasury stock	(2,049		)	(1,337		)

Divestitures

Divestitures	6 Months Ended
	Jun. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Divestitures	'
	Divestitures
	On December 10, 2013, the Company completed the sale of its West Tavaputs natural gas assets in the Uinta Basin (the "West Tavaputs Divestiture"). The Company received $308.7 million in cash proceeds, after closing adjustments. The divestiture proceeds are subject to various purchase price adjustments incurred in the normal course of business and will be finalized during 2014. The Company recognized an impairment loss of $1.0 million during the six months ended June 30, 2014 related to these assets based upon a true up of previously estimated fair value relative to carrying value. The initial impairment loss of $209.5 million was recognized during the year ended December 31, 2013.

LongTerm_Debt

Long-Term Debt	6 Months Ended
	Jun. 30, 2014
Debt Disclosure [Abstract]	'
Long-Term Debt	'
	Long-Term Debt
	The Company's outstanding debt is summarized below:
			As of June 30, 2014									As of December 31, 2013
		Maturity Date	Principal			Unamortized			Carrying			Principal		Unamortized		Carrying
						Discount			Amount					Discount		Amount
			(in thousands)
	Amended Credit Facility (1)	October 31, 2016	$	250,000		$	—		$	250,000		$	115,000	$	—	$	115,000
	Convertible Notes (2)	March 15, 2028 (3)	25,344			—			25,344			25,344		—		25,344
	7.625% Senior Notes (4)	October 1, 2019	400,000			—			400,000			400,000		—		400,000
	7.0% Senior Notes (5)	October 15, 2022	400,000			—			400,000			400,000		—		400,000
	Lease Financing Obligation (6)	August 10, 2020	41,044			—			41,044			43,329		—		43,329
	Total Debt		$	1,116,388		$	—		$	1,116,388		$	983,673	$	—	$	983,673
	Less: Current Portion of Long-Term Debt		4,685			—			4,685			4,591		—		4,591
	Total Long-Term Debt		$	1,111,703		$	—		$	1,111,703		$	979,082	$	—	$	979,082
	-1	The recorded value of the Amended Credit Facility approximates its fair value due to its floating rate structure.
	-2	The aggregate estimated fair value of the Convertible Notes was approximately $25.3 million and $25.1 million as of June 30, 2014 and December 31, 2013, respectively, based on reported market trades of these instruments.
	-3	The Company has the right at any time, with at least 30 days' notice, to call the Convertible Notes, and the holders have the right to require the Company to purchase the notes on each of March 20, 2015, March 20, 2018 and March 20, 2023.
	-4	The aggregate estimated fair value of the 7.625% Senior Notes was approximately $430.1 million and $430.2 million as of June 30, 2014 and December 31, 2013, respectively, based on reported market trades of these instruments.
	-5	The aggregate estimated fair value of the 7.0% Senior Notes was approximately $424.0 million and $417.0 million as of June 30, 2014 and December 31, 2013, respectively, based on reported market trades of these instruments.
	-6	The aggregate estimated fair value of the Lease Financing Obligation was approximately $39.4 million as of June 30, 2014, and $41.7 million as of December 31, 2013. 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.
	Amended Credit Facility
	The Company's Amended Credit Facility has a maturity date of October 31, 2016 and current commitments and borrowing base of $625.0 million. As of June 30, 2014, the Company had $250.0 million outstanding under the Amended Credit Facility. As credit support for future payment under a contractual obligation, a $26.0 million letter of credit has been issued under the Amended Credit Facility, which reduced the borrowing capacity of the Amended Credit Facility as of June 30, 2014 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 commitment fee is between 0.375% to 0.5% based on borrowing base utilization. The average annual interest rates incurred on the Amended Credit Facility were 1.9% and 1.7% for the three months ended June 30, 2014 and 2013, and 1.8% and 1.7% for the six months ended June 30, 2014 and 2013, respectively.
	The borrowing base is required to be re-determined twice per year. On May 1, 2014, the borrowing base was reaffirmed at $625.0 million based on year-end 2013 reserves and our hedge position. Future semi-annual borrowing bases will be computed based on proved oil, natural gas and NGL reserves, hedge positions and estimated future cash flows from those reserves, 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 since issuance.
	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. The Company settled the notes in cash. After the redemption, $25.3 million aggregate principal amount of the Convertible Notes was outstanding. 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, 2015, 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 beginning April 1, 2012. 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 Company's Convertible Notes and 7.0% Senior Notes. The 7.625% Senior Notes are redeemable at the Company's option on October 1, 2015 at a 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 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 Company's Convertible Notes and 7.625% Senior Notes. The 7.0% Senior Notes are redeemable at the Company's option on October 15, 2017 at a 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 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
	On July 23, 2012, the Company entered into the Lease Financing Obligation, whereby the Company received $100.8 million through the sale and subsequent leaseback of existing 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 where the Company may purchase the equipment for $36.6 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 11 for discussion of aggregate minimum future lease payments. As part of the West Tavaputs Divestiture, the purchaser assumed approximately 51% of the Lease Financing Obligation, including the early buyout option, related to West Tavaputs equipment.
	The following table summarizes, for the periods indicated, the cash or accrued portion of interest expense related to the Amended Credit Facility, the 9.875% Senior Notes that were redeemed in full on July 15, 2013, Convertible Notes, 7.625% Senior Notes, 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 June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
		(in thousands)
	Amended Credit Facility (1)
	Cash interest	$	1,543		$	1,051		$	2,621		$	1,915
	Non-cash interest	$	585		$	586		$	1,171		$	1,171
	9.875% Senior Notes (2)
	Cash interest	$	—		$	6,172		$	—		$	12,344
	Non-cash interest	$	—		$	682		$	—		$	1,361
	Convertible Notes (3)
	Cash interest	$	324		$	320		$	634		$	633
	Non-cash interest	$	2		$	1		$	3		$	3
	7.625% Senior Notes (4)
	Cash interest	$	7,625		$	7,625		$	15,250		$	15,250
	Non-cash interest	$	272		$	263		$	544		$	526
	7.0% Senior Notes (5)
	Cash interest	$	7,000		$	7,000		$	14,000		$	14,000
	Non-cash interest	$	203		$	194		$	406		$	389
	Lease Financing Obligation (6)
	Cash interest	$	255		$	768		$	517		$	1,555
	Non-cash interest	$	4		$	8		$	8		$	16
	-1	Cash interest includes amounts related to interest and commitment fees paid on the Amended Credit Facility and participation and fronting fees paid on the letter of credit.
	-2	The stated interest rate for the 9.875% Senior Notes was 9.875% per annum with an effective interest rate of 11.2% per annum. The Company redeemed the 9.875% Senior Notes in full on July 15, 2013.
	-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 $25.3 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 from $0.8 million to $0.3 million for the three months ended June 30, 2013 and June 30, 2014, respectively, and from $1.6 million to $0.5 million for the six months ended June 30, 2013 and June 30, 2014, respectively, is due to the West Tavaputs Divestiture. The purchaser assumed approximately 51% of the Lease Financing Obligation, including the buyout option, related to West Tavaputs equipment, leaving the Company with a balance of $41.0 million as of June 30, 2014.

Asset_Retirement_Obligations

Asset Retirement Obligations	6 Months Ended
	Jun. 30, 2014
Asset Retirement Obligation Disclosure [Abstract]	'
Asset Retirement Obligations	'
	Asset Retirement Obligations
	A reconciliation of the Company's asset retirement obligations for the six months ended June 30, 2014 is as follows (in thousands):
	As of December 31, 2013	$	43,005
	Liabilities incurred	2,045
	Liabilities settled	(1,247		)
	Disposition of properties	—
	Accretion expense	1,658
	Revisions to estimate	1,150
	As of June 30, 2014	$	46,611
	Less: Current asset retirement obligations	6,168
	Long-term asset retirement obligations	$	40,443

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2014
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 June 30, 2014
		Level 1		Level 2		Level 3		Total
		(in thousands)
	Assets
	Deferred Compensation Plan	$	785	$	—	$	—	$	785
	Cash Equivalents - Money Market Funds	53		—		—		53
	Commodity Derivatives	—		4,461		—		4,461
	Liabilities
	Commodity Derivatives	$	—	$	61,690	$	—	$	61,690
		As of December 31, 2013
		Level 1		Level 2		Level 3		Total
		(in thousands)
	Assets
	Deferred Compensation Plan	$	941	$	—	$	—	$	941
	Cash Equivalents - Money Market Funds	53		—		—		53
	Commodity Derivatives	—		11,483		—		11,483
	Liabilities
	Commodity Derivatives	$	—	$	14,771	$	—	$	14,771
	All fair values 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 (as discussed in more detail in Note 10) 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 Company also has highly liquid short term investments in money market funds. The deferred compensation plan financial assets are reported at fair value based on active market quotes, which represent Level 1 inputs. The money market fund investments are recorded at carrying value, which approximates fair value, which represent Level 1 inputs. The fair values of the Company's fixed rate 7.625% Senior Notes and 7.0% Senior Notes totaled $854.1 million as of June 30, 2014. The fair values of the Company's fixed rate 7.625% Senior Notes and 7.0% Senior Notes totaled $847.2 million as of December 31, 2013. 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 Company's Amended Credit Facility, Convertible Notes or Lease Financing Obligation. The Amended Credit Facility balance of $250.0 million and $115.0 million as of June 30, 2014 and December 31, 2013, respectively, approximates its fair value due to its floating rate structure. The Convertible Notes fair value of $25.3 million and $25.1 million as of June 30, 2014 and December 31, 2013, 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 $39.4 million and $41.7 million as of June 30, 2014 and December 31, 2013, 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 June 30, 2014 and December 31, 2013, the Company did not have assets or liabilities that were measured on a recurring basis classified under a Level 3 fair value hierarchy.

Derivative_Instruments

Derivative Instruments	6 Months Ended
	Jun. 30, 2014
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 June 30, 2014
	Balance Sheet	Gross Amounts of				Gross Amounts				Net Amounts of Derivative
		Recognized				Offset in the Balance				Assets Presented in the
		Derivative Assets				Sheet				Balance Sheet
		(in thousands)
	Derivative assets	$	3,411			$	(3,411	)	(1)	$	—
	Deferred financing costs and other noncurrent assets	1,050				(1,050		)	(1)	—			(3)
	Total derivative assets	$	4,461			$	(4,461	)		$	—
		Gross Amounts of				Gross Amounts				Net Amounts of Derivative
		Recognized				Offset in the Balance				Liabilities Presented in
		Derivative				Sheet				the Balance Sheet
		Liabilities
		(in thousands)
	Derivative liabilities	$	(44,790	)		$	3,411		(1)	$	(41,379	)
	Derivatives and other noncurrent liabilities	(16,900		)		1,050			(1)	(15,850		)	(4)
	Total derivative liabilities	$	(61,690	)		$	4,461			$	(57,229	)
		As of December 31, 2013
	Balance Sheet	Gross Amounts of				Gross Amounts				Net Amounts of Derivative
		Recognized				Offset in the Balance				Assets Presented in the
		Derivative Assets				Sheet				Balance Sheet
		(in thousands)
	Derivative assets	$	8,259			$	(8,086	)	(2)	$	173
	Deferred financing costs and other noncurrent assets	3,224				(685		)	(2)	2,539			(3)
	Total derivative assets	$	11,483			$	(8,771	)		$	2,712
		Gross Amounts of				Gross Amounts				Net Amounts of Derivative
		Recognized				Offset in the Balance				Liabilities Presented in
		Derivative				Sheet				the Balance Sheet
		Liabilities
		(in thousands)
	Derivative liabilities	$	(14,074	)		$	8,086		(1)	$	(5,988	)
	Derivatives and other noncurrent liabilities	(697		)		685			(1)	(12		)	(4)
	Total derivative liabilities	$	(14,771	)		$	8,771			$	(6,000	)
	-1	Derivative asset balances are netted against derivative liability balances with the same counterparty, and therefore are presented as a net liability in the Unaudited Consolidated Balance Sheets.
	-2	Derivative liability balances are netted against derivative asset balances with the same counterparty, and therefore are presented as a net asset in the Unaudited Consolidated Balance Sheets.
	-3	As of June 30, 2014 and December 31, 2013, this line item in the Unaudited Consolidated Balance Sheets included $17.4 million and $19.2 million of deferred financing costs and other noncurrent assets, respectively.
	-4	As of June 30, 2014 and December 31, 2013, this line item in the Unaudited Consolidated Balance Sheets included $3.0 million and $3.5 million of other noncurrent liabilities, respectively.
	The following table summarizes the cash flow hedge gains, net of tax, as of the periods indicated:
	Derivatives Qualifying as Cash Flow Hedges			Three Months Ended June 30,								Six Months Ended June 30,
				2014				2013				2014				2013
				(in thousands)
	Amount of gain reclassified from AOCI into income (net of tax) (1)(2)	Commodity Hedges		$	239			$	1,210			$	336			$	2,502
	-1	Gains reclassified from accumulated other comprehensive income ("AOCI") into income are included in the oil, gas and NGL production revenues in the Unaudited Consolidated Statements of Operations.
	-2	Presented net of income tax expense of $0.1 million and $0.7 million for the three months ended June 30, 2014 and 2013, respectively, and $0.2 million and $1.5 million for the six months ended June 30, 2014 and 2013, respectively.
	As of June 30, 2014, 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:
		July – December			For the year			For the  year			For the  year
		2014			2015			2016			2017
	Oil (Bbls)	1,950,400			4,077,500			1,554,000			182,500
	Natural gas (MMbtu)	12,570,000			7,300,000			1,830,000			—
	Natural gas liquids (Bbls)	189,286			—			—			—
	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 June 30,								Six Months Ended June 30,
		2014				2013				2014				2013
		(in thousands)
	Commodity derivative gain settlements on derivatives designated as cash flow hedges (1)	$	382			$	1,936			$	538			$	4,003
	Total commodity derivative gain (loss) (2)	(46,775		)		36,839				(71,930		)		6,988
	-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 nine different counterparties as of June 30, 2014. 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, affiliates of lenders in the Amended Credit Facility or potential 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 the Company under 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	6 Months Ended
	Jun. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	Income tax expense (benefit) for the three and six months ended June 30, 2014 and 2013 differs from the amounts that would be provided by applying the U.S. federal income tax rate to income before income taxes principally due to the effect of state income taxes, stock-based compensation and other operating expenses not deductible for income tax purposes. The effective tax rate of 29.7% for the three months ended June 30, 2014 is primarily due to an increase in permanent adjustments to taxable income relative to projected pre-tax income. The effective tax rate of 35.3% for the six months ended June 30, 2014 is primarily due to permanent adjustments to taxable income relative to the projected pretax income.

Equity_Incentive_Compensation_

Equity Incentive Compensation Plans and Other Employee Benefits	6 Months Ended
	Jun. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Equity Incentive Compensation Plans and Other Employee Benefits	'
	Equity Incentive Compensation Plans and Other Employee Benefits
	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 June 30,						Six Months Ended June 30,
		2014			2013			2014				2013
		(in thousands)
	Common stock options	$	497		$	727		$	1,126			$	3,217
	Nonvested equity common stock	1,548			1,588			3,219				3,988
	Nonvested equity common stock units	260			312			509				712
	Nonvested performance-based equity	146			530			964				698
	Total	$	2,451		$	3,157		$	5,818			$	8,615
	Unrecognized compensation cost as of June 30, 2014 was $24.1 million related to grants of nonvested stock options and nonvested equity shares of common stock that are expected to be recognized over a weighted-average period of 2.7 years.
	Nonvested Equity Shares. The following table presents the equity awards granted pursuant to the Company's various stock compensation plans:
		Three Months Ended June 30, 2014					Three Months Ended June 30, 2013
		Number of		Weighted Average			Number of			Weighted Average
		Shares		Grant Date Fair			Shares			Grant Date Fair
				Value Per Share						Value Per Share
	Nonvested equity common stock	23,626		$	23.91		16,880			$	19.54
	Nonvested equity common stock units	700		$	26.78		43,824			$	22.38
	Nonvested performance-based equity shares	44,540		$	20.92		13,007			$	17.26
	Total shares granted	68,866					73,711
		Six Months Ended June 30, 2014					Six Months Ended June 30, 2013
		Number of		Weighted Average			Number of			Weighted Average
		Shares		Grant Date Fair			Shares			Grant Date Fair
				Value Per Share						Value Per Share
	Nonvested equity common stock	489,940		$	22.54		557,260			$	17.32
	Nonvested equity common stock units	1,432		$	26.18		52,219			$	22.04
	Nonvested performance-based equity shares	293,115		$	19.81		287,986			$	16.6
	Total shares granted	784,487					897,465
	Performance Share Programs
	2014 Program. In February 2014, the Compensation Committee approved a new performance share program (the "2014 Program") pursuant to the 2012 Equity Incentive Plan. The performance-based awards contingently vest in May 2017, 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, 2016, 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% 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 shares will be prorated based on the actual results compared to the threshold, target and stretch goals. If the threshold metrics are not met, no shares will vest. In any event, the total number of shares of common stock that could vest will not exceed 200% of the original number of performance shares granted. At the end of the three year vesting period, any shares that have not vested will be forfeited. All compensation expense related to the TSR metric will be recognized if the requisite service period is fulfilled, even if the market condition is not achieved. All compensation expense related to the discretionary cash flow metric will be based upon the number of shares expected to vest at the end of the three year period.

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2014
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 June 30, 2014
		(in thousands)
	2014	$	2,990
	2015	5,979
	2016	5,979
	2017	5,979
	2018	5,979
	Thereafter	18,781
	Total	$	45,687
	Gathering, Transportation and Processing Charges. The Company has entered into contracts that provide firm gathering and transportation capacity on pipeline systems and firm processing charges. The remaining terms on these contracts range from two to seven years and require the Company to pay gathering, transportation and processing charges regardless of the amount of pipeline capacity utilized by the Company. The Company paid $7.4 million and $15.1 million of firm gathering and transportation charges for the three and six months ended June 30, 2014, respectively. The Company paid $9.5 million and $18.0 million of firm gathering and transportation charges for the three and six months ended June 30, 2013, respectively. The Company paid $1.4 million and $2.0 million of firm processing charges for the three and six months ended June 30, 2013, respectively. All gathering and transportation costs, including demand charges and processing charges, are included in gathering, transportation and processing expense in the Unaudited Consolidated Statements of Operations.
	The amounts in the table below represent the Company's gross future minimum transportation charges. However, the Company will record in its financial statements only the Company's proportionate share based on the Company's working interest and net revenue interest, which will vary from property to property. From time to time, we may sell certain portions of firm capacity on various pipelines, as business or operations conditions warrant, to mitigate our exposure on unused transportation capacity.
		As of June 30, 2014
		(in thousands)
	2014	$	18,254
	2015	36,717
	2016	35,466
	2017	33,085
	2018	33,521
	Thereafter	63,813
	Total	$	220,856
	Lease and Other Commitments. The Company has one take-or-pay purchase agreement for supply of carbon dioxide ("CO2"), which has a total financial commitment of $1.7 million. The CO2 is for use in fracture stimulation operations. Under this contract, the Company is obligated to purchase a minimum monthly volume 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.
	The Company leases office space, vehicles and certain equipment under non-cancelable operating leases. Office lease expense was $0.3 million and $0.5 million for the three months ended June 30, 2014 and 2013, and $0.7 million and $1.0 million for the six months ended June 30, 2014 and 2013, respectively. Additionally, the Company has entered into various long-term agreements for telecommunication services. Future minimum annual payments under lease and other agreements are as follows:
		As of June 30, 2014
		(in thousands)
	2014	$	1,934
	2015 (1)	9,939
	2016	2,713
	2017	2,540
	2018	2,528
	Thereafter	633
	Total	$	20,287
	-1	Includes a drilling carry in the amount of $8.5 million from a purchase, sale and exploration agreement related to acreage in the Powder River Basin. As of June 30, 2014, the Company has satisfied $1.7 million of this carry. The Company will owe the remaining carry balance if not satisfied by October 1, 2015.
	Litigation. The Company is subject to litigation, claims and governmental and regulatory proceedings arising in the course of ordinary 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	6 Months Ended
	Jun. 30, 2014
Text Block [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 are registered securities, 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 Rule 3-10 of Regulation S-X of the Securities Exchange Act of 1934, as amended.
	During the three 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. 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 June 30, 2014
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Assets:
	Current assets	$	165,929		$	52		$	—		$	165,981
	Property and equipment, net	2,275,639			75,317			—			2,350,956
	Intercompany receivable (payable)	52,927			(52,927		)	—			—
	Investment in subsidiaries	16,315			—			(16,315		)	—
	Noncurrent assets	17,375			—			—			17,375
	Total assets	$	2,528,185		$	22,442		$	(16,315	)	$	2,534,312
	Liabilities and Stockholders' Equity:
	Current liabilities	$	236,722		$	1,247		$	—		$	237,969
	Long-term debt	1,111,703			—			—			1,111,703
	Deferred income taxes	151,463			3,255			—			154,718
	Other noncurrent liabilities	57,702			1,625			—			59,327
	Stockholders' equity	970,595			16,315			(16,315		)	970,595
	Total liabilities and stockholders' equity	$	2,528,185		$	22,442		$	(16,315	)	$	2,534,312
		As of December 31, 2013
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Assets:
	Current assets	$	154,986		$	2,261		$	—		$	157,247
	Property and equipment, net	2,127,624			74,872			—			2,202,496
	Intercompany receivable (payable)	59,076			(59,076		)	—			—
	Investment in subsidiaries	12,063			—			(12,063		)	—
	Noncurrent assets	21,770			—			—			21,770
	Total assets	$	2,375,519		$	18,057		$	(12,063	)	$	2,381,513
	Liabilities and Stockholders' Equity:
	Current liabilities	$	192,106		$	613		$	—		$	192,719
	Long-term debt	979,082			—			—			979,082
	Deferred income taxes	158,071			3,255			—			161,326
	Other noncurrent liabilities	40,542			2,126			—			42,668
	Stockholders' equity	1,005,718			12,063			(12,063		)	1,005,718
	Total liabilities and stockholders' equity	$	2,375,519		$	18,057		$	(12,063	)	$	2,381,513
	Condensed Consolidating Statements of Operations
		Three Months Ended June 30, 2014
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Operating and other revenues	$	138,355		$	6,653		$	—		$	145,008
	Operating expenses	(99,809		)	(4,264		)	—			(104,073		)
	General and administrative	(14,521		)	—			—			(14,521		)
	Interest income and other income (expense)	(64,279		)	35			—			(64,244		)
	Income (loss) before income taxes and equity in earnings of subsidiaries	(40,254		)	2,424			—			(37,830		)
	Benefit from income taxes	11,244			—			—			11,244
	Equity in earnings of subsidiaries	2,424			—			(2,424		)	—
	Net income (loss)	$	(26,586	)	$	2,424		$	(2,424	)	$	(26,586	)
		Six Months Ended June 30, 2014
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Operating and other revenues	$	260,038		$	12,658		$	—		$	272,696
	Operating expenses	(188,696		)	(8,441		)	—			(197,137		)
	General and administrative	(29,928		)	—			—			(29,928		)
	Interest income and other income (expense)	(106,490		)	35			—			(106,455		)
	Income (loss) before income taxes and equity in earnings of subsidiaries	(65,076		)	4,252			—			(60,824		)
Benefit from income taxes	21,489			—			—			21,489
Equity in earnings (loss) of subsidiaries	4,252			—			(4,252		)	—
Net income (loss)	$	(39,335	)	$	4,252		$	(4,252	)	$	(39,335	)
	Three Months Ended June 30, 2013
	Parent			Guarantor			Intercompany			Consolidated
	Issuer			Subsidiaries			Eliminations
	(in thousands)
Operating and other revenues	$	142,298		$	1		$	—		$	142,299
Operating expenses	(118,295		)	—			—			(118,295		)
General and administrative	(13,273		)	—			—			(13,273		)
Interest and other income (expense)	12,145			—			—			12,145
Income before income taxes and equity in earnings of subsidiaries	22,875			1			—			22,876
Provision for income taxes	(8,603		)	—			—			(8,603		)
Equity in earnings of subsidiaries	1			—			(1		)	—
Net income (loss)	$	14,273		$	1		$	(1	)	$	14,273
	Six Months Ended June 30, 2013
	Parent			Guarantor			Intercompany			Consolidated
	Issuer			Subsidiaries			Eliminations
	(in thousands)
Operating and other revenues	$	280,576		$	—		$	—		$	280,576
Operating expenses	(234,214		)	—			—			(234,214		)
General and administrative	(33,855		)	—			—			(33,855		)
Interest and other income (expense)	(42,209		)	—			—			(42,209		)
Income (loss) before income taxes and equity in earnings of subsidiaries	(29,702		)	—			—			(29,702		)
Benefit from income taxes	10,824			—			—			10,824
Equity in earnings (loss) of subsidiaries	—			—			—			—
Net income (loss)	$	(18,878	)	$	—		$	—		$	(18,878	)
Condensed Consolidating Statements of Comprehensive Income (Loss)
	Three Months Ended June 30, 2014
	Parent			Guarantor			Intercompany			Consolidated
	Issuer			Subsidiaries			Eliminations
	(in thousands)
Net income (loss)	$	(26,586	)	$	2,424		$	(2,424	)	$	(26,586	)
Other Comprehensive Loss, net of tax:
Effect of derivative financial instruments	(239		)	—			—			(239		)
Other comprehensive loss	(239		)	—			—			(239		)
Comprehensive income (loss)	$	(26,825	)	$	2,424		$	(2,424	)	$	(26,825	)
	Six Months Ended June 30, 2014
	Parent			Guarantor			Intercompany			Consolidated
	Issuer			Subsidiaries			Eliminations
	(in thousands)
Net income (loss)	$	(39,335	)	$	4,252		$	(4,252	)	$	(39,335	)
Other Comprehensive Loss, net of tax:
Effect of derivative financial instruments	(336		)	—			—			(336		)
Other comprehensive loss	(336		)	—			—			(336		)
Comprehensive income (loss)	$	(39,671	)	$	4,252		$	(4,252	)	$	(39,671	)
	Three Months Ended June 30, 2013
	Parent			Guarantor			Intercompany			Consolidated
	Issuer			Subsidiaries			Eliminations
	(in thousands)
Net income (loss)	$	14,273		$	1		$	(1	)	$	14,273
Other Comprehensive Loss, net of tax:
Effect of derivative financial instruments	(1,210		)	—			—			(1,210		)
Other comprehensive loss	(1,210		)	—			—			(1,210		)
Comprehensive income (loss)	$	13,063		$	1		$	(1	)	$	13,063
	Six Months Ended June 30, 2013
	Parent			Guarantor			Intercompany			Consolidated
	Issuer			Subsidiaries			Eliminations
	(in thousands)
Net income (loss)	$	(18,878	)	$	—		$	—		$	(18,878	)
Other Comprehensive Loss, net of tax:
Effect of derivative financial instruments	(2,502		)	—			—			(2,502		)
Other comprehensive loss	(2,502		)	—			—			(2,502		)
Comprehensive income (loss)	$	(21,380	)	$	—		$	—		$	(21,380	)
Condensed Consolidating Statements of Cash Flows
	Six Months Ended June 30, 2014
	Parent			Guarantor			Intercompany			Consolidated
	Issuer			Subsidiaries			Eliminations
	(in thousands)
Cash flows from operating activities	$	115,705		$	11,713		$	—		$	127,418
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions	(257,471		)	(6,874		)	—			(264,345		)
Additions to furniture, fixtures and other	(856		)	—			—			(856		)
Proceeds from sale of properties and other investing activities	7,640			535			—			8,175
Intercompany transfers	5,374			—			(5,374		)	—
Cash flows from financing activities:
Proceeds from debt	135,000			—			—			135,000
Principal payments on debt	(2,285		)	—			—			(2,285		)
Intercompany transfers	—			(5,374		)	5,374			—
Other financing activities	(1,923		)	—			—			(1,923		)
Change in cash and cash equivalents	1,184			—			—			1,184
Beginning cash and cash equivalents	54,545			50			—			54,595
Ending cash and cash equivalents	$	55,729		$	50		$	—		$	55,779
	Six Months Ended June 30, 2013
	Parent			Guarantor			Intercompany			Consolidated
	Issuer			Subsidiaries			Eliminations
	(in thousands)
Cash flows from operating activities	$	117,209		$	5,820		$	—		$	123,029
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions	(204,020		)	(12,632		)	—			(216,652		)
Additions to furniture, fixtures and other	731			(1,918		)	—			(1,187		)
Proceeds from sale of properties and other investing activities	4,086			—			—			4,086
Cash flows from financing activities:
Proceeds from debt	80,000			—			—			80,000
Principal payments on debt	(4,501		)	—			—			(4,501		)
Intercompany transfers	(5,546		)	5,546			—			—
Other financing activities	(1,345		)	—			—			(1,345		)
Change in cash and cash equivalents	(13,386		)	(3,184		)	—			(16,570		)
Beginning cash and cash equivalents	79,395			50			—			79,445
Ending cash and cash equivalents	$	66,009		$	(3,134	)	$	—		$	62,875

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2014
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 2013 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 the expected cash settlement of the Company's 5% Convertible Senior Notes due 2028 ("Convertible Notes") in computing diluted earnings per share, 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 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 undeveloped 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 when incurred. The costs of development wells are capitalized whether proved reserves are added or not. Oil and gas lease acquisition costs are also capitalized.
	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. A gain or loss is recognized for all other sales of proved properties and is classified in other operating revenues. 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 June 30, 2014			As of December 31, 2013
		(in thousands)
	Proved properties	$	494,371		$	485,427
	Wells and related equipment and facilities	2,421,552			2,192,754
	Support equipment and facilities	180,421			177,224
	Materials and supplies	10,961			8,518
	Total proved oil and gas properties	$	3,107,305		$	2,863,923
	Unproved properties	212,623			239,925
	Wells and facilities in progress	86,849			56,674
	Total unproved oil and gas properties, excluded from amortization	$	299,472		$	296,599
	Accumulated depreciation, depletion, amortization and impairment	(1,072,804		)	(976,339		)
	Total oil and gas properties, net	$	2,333,973		$	2,184,183
	All exploratory wells are evaluated for economic viability within one year of well completion. Exploratory wells that discover potentially economic reserves in areas where a major capital expenditure would be required before production could begin, and where the economic viability of that major capital expenditure depends upon the successful completion of further exploratory work in the area, remain capitalized if the well finds a sufficient quantity of reserves to justify its completion as a producing well and the Company is making sufficient progress assessing the reserves and the economic and operating viability of the project. As of June 30, 2014 and December 31, 2013, there were no exploratory well costs that had been capitalized for a period greater than one year since the completion of drilling.
	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 cash flows of its oil and gas properties and compares such undiscounted future cash flows to the carrying amount of the oil and gas properties to determine if the carrying amount is recoverable. If the carrying value of a property exceeds the undiscounted future cash flows, the Company will impair the carrying value to fair value based on an analysis of quantitative and qualitative factors. The Company has no guarantee that the undiscounted future 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, 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 expected cash flows projected.
	The Company recognized non-cash impairment charges, which were included within impairment, dry hole costs and abandonment expense in the Unaudited Consolidated Statements of Operations, as follows:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
		(in thousands)
	Non-cash impairment of proved oil and gas properties (1)	$	—		$	—		$	1,038		$	—
	Non-cash impairment of unproved oil and gas properties	—			—			—			—
	Non-cash impairment of inventory (2)	340			—			340			—
	Dry hole costs	(12		)	113			94			964
	Abandonment expense	1,415			1,069			2,032			7,319
	Total non-cash impairment, dry hole costs and abandonment expense	$	1,743		$	1,182		$	3,504		$	8,283
	-1	Non-cash impairment of proved oil and gas properties for the six months ended June 30, 2014 related to the Company's West Tavaputs properties based upon a true up of previously estimated fair value relative to carrying value. These assets were sold in December 2013. See Note 4.
	-2	Non-cash impairment of inventory related to impairing unused oil and gas related equipment to fair value.
	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 June 30, 2014			As of December 31, 2013
		(in thousands)
	Accrued drilling, completion and facility costs	$	80,132		$	54,750
	Accrued lease operating, gathering, transportation and processing expenses	12,791			17,317
	Accrued general and administrative expenses	8,504			14,605
	Trade payables and other	22,866			29,256
	Total accounts payable and accrued liabilities	$	124,293		$	115,928
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 and gas 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' 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 June 30, 2014 and 2013 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.
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.
	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.
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 months and six months ended June 30, 2014 and the six months ended June 30, 2013.
	In satisfaction of its obligation upon conversion of the Convertible Notes, the Company may elect to deliver, at its option, cash, shares of its common stock or a combination of cash and shares of its common stock. As of June 30, 2014, the Company expected to settle the remaining Convertible Notes in cash. Therefore, the treasury stock method was used to measure the potentially dilutive impact of shares associated with that remaining conversion feature. The Company has the right with at least 30 days' notice to call the Convertible Notes and the holders have the right to require the Company to purchase the notes on March 20, 2015. The Convertible Notes have not been dilutive since their issuance in March 2008 and, therefore, did not impact the diluted net income (loss) per common share calculation for the three and six months ended June 30, 2014 and 2013. The diluted net income (loss) per common share excludes the anti-dilutive effect of 1,120,210 and 2,857,757 shares of stock options and nonvested performance-based shares of common stock for the three months ended June 30, 2014 and 2013, and 1,257,716 and 2,836,480 shares of stock options and nonvested performance-based shares of common stock for the six months ended June 30, 2014 and 2013, respectively.
	The following table sets forth the calculation of basic and diluted earnings (loss) per share:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
		(in thousands, except per share amounts)
	Net income (loss)	$	(26,586	)	$	14,273		$	(39,335	)	$	(18,878	)
	Basic weighted-average common shares outstanding in period	47,997			47,469			47,944			47,411
	Add dilutive effects of stock options and nonvested equity shares of common stock	—			147			—			—
	Diluted weighted-average common shares outstanding in period	47,997			47,616			47,944			47,411
	Basic net income (loss) per common share	$	(0.55	)	$	0.3		$	(0.82	)	$	(0.40	)
	Diluted net income (loss) per common share	$	(0.55	)	$	0.3		$	(0.82	)	$	(0.40	)
New Accounting Pronouncements	'
	New Accounting Pronouncements. 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. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. The Company is currently evaluating the potential impact that the adoption will have on the Company’s disclosures and financial statements.
	In June 2014, the FASB issued ASU 2014-12, Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period. The objective of this update is to provide guidance on the treatment of a performance target that could be achieved after the requisite service period. ASU 2014-12 is effective for annual periods and interim periods within those annual periods beginning after December 15, 2015. The adoption of this standard will not have an impact on the Company's consolidated financial statements.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Summary of Accounts Receivable	'
	Accounts receivable is comprised of the following:
		As of June 30, 2014			As of December 31, 2013
		(in thousands)
	Accrued oil, gas and NGL sales	$	61,381		$	67,583
	Due from joint interest owners	23,890			23,507
	Other	6,630			6,517
	Allowance for doubtful accounts	(21		)	(21		)
	Total accounts receivable	$	91,880		$	97,586
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 June 30, 2014			As of December 31, 2013
		(in thousands)
	Proved properties	$	494,371		$	485,427
	Wells and related equipment and facilities	2,421,552			2,192,754
	Support equipment and facilities	180,421			177,224
	Materials and supplies	10,961			8,518
	Total proved oil and gas properties	$	3,107,305		$	2,863,923
	Unproved properties	212,623			239,925
	Wells and facilities in progress	86,849			56,674
	Total unproved oil and gas properties, excluded from amortization	$	299,472		$	296,599
	Accumulated depreciation, depletion, amortization and impairment	(1,072,804		)	(976,339		)
	Total oil and gas properties, net	$	2,333,973		$	2,184,183
Non-Cash Impairment Charges, Included within Impairment, Dry Hole Costs and Abandonment Expense in Consolidated Statements of Operations	'
	The Company recognized non-cash impairment charges, which were included within impairment, dry hole costs and abandonment expense in the Unaudited Consolidated Statements of Operations, as follows:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
		(in thousands)
	Non-cash impairment of proved oil and gas properties (1)	$	—		$	—		$	1,038		$	—
	Non-cash impairment of unproved oil and gas properties	—			—			—			—
	Non-cash impairment of inventory (2)	340			—			340			—
	Dry hole costs	(12		)	113			94			964
	Abandonment expense	1,415			1,069			2,032			7,319
	Total non-cash impairment, dry hole costs and abandonment expense	$	1,743		$	1,182		$	3,504		$	8,283
	-1	Non-cash impairment of proved oil and gas properties for the six months ended June 30, 2014 related to the Company's West Tavaputs properties based upon a true up of previously estimated fair value relative to carrying value. These assets were sold in December 2013. See Note 4.
	-2	Non-cash impairment of inventory related to impairing unused oil and gas related equipment to fair value.
Accounts Payable and Accrued Liabilities	'
	Accounts payable and accrued liabilities are comprised of the following:
		As of June 30, 2014			As of December 31, 2013
		(in thousands)
	Accrued drilling, completion and facility costs	$	80,132		$	54,750
	Accrued lease operating, gathering, transportation and processing expenses	12,791			17,317
	Accrued general and administrative expenses	8,504			14,605
	Trade payables and other	22,866			29,256
	Total accounts payable and accrued liabilities	$	124,293		$	115,928
Calculation of Basic and Diluted Earnings (Loss) Per Share	'
	The following table sets forth the calculation of basic and diluted earnings (loss) per share:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
		(in thousands, except per share amounts)
	Net income (loss)	$	(26,586	)	$	14,273		$	(39,335	)	$	(18,878	)
	Basic weighted-average common shares outstanding in period	47,997			47,469			47,944			47,411
	Add dilutive effects of stock options and nonvested equity shares of common stock	—			147			—			—
	Diluted weighted-average common shares outstanding in period	47,997			47,616			47,944			47,411
	Basic net income (loss) per common share	$	(0.55	)	$	0.3		$	(0.82	)	$	(0.40	)
	Diluted net income (loss) per common share	$	(0.55	)	$	0.3		$	(0.82	)	$	(0.40	)

Supplemental_Disclosures_of_Ca1

Supplemental Disclosures of Cash Flow Information (Tables)	6 Months Ended
	Jun. 30, 2014
Supplemental Cash Flow Elements [Abstract]	'
Supplemental Cash Flow Information	'
	Supplemental cash flow information is as follows:
		Six Months Ended June 30,
		2014			2013
		(in thousands)
	Cash paid for interest, net of amount capitalized	$	33,173		$	45,709
	Cash paid for income taxes	1			1,861
	Supplemental disclosures of non-cash investing and financing activities:
	Current liabilities	82,782			68,731
	Net increase in asset retirement obligations	3,195			1,888
	Retirement of treasury stock	(2,049		)	(1,337		)

LongTerm_Debt_Tables

Long-Term Debt (Tables)	6 Months Ended
	Jun. 30, 2014
Debt Disclosure [Abstract]	'
Outstanding Debt	'
	The Company's outstanding debt is summarized below:
			As of June 30, 2014									As of December 31, 2013
		Maturity Date	Principal			Unamortized			Carrying			Principal		Unamortized		Carrying
						Discount			Amount					Discount		Amount
			(in thousands)
	Amended Credit Facility (1)	October 31, 2016	$	250,000		$	—		$	250,000		$	115,000	$	—	$	115,000
	Convertible Notes (2)	March 15, 2028 (3)	25,344			—			25,344			25,344		—		25,344
	7.625% Senior Notes (4)	October 1, 2019	400,000			—			400,000			400,000		—		400,000
	7.0% Senior Notes (5)	October 15, 2022	400,000			—			400,000			400,000		—		400,000
	Lease Financing Obligation (6)	August 10, 2020	41,044			—			41,044			43,329		—		43,329
	Total Debt		$	1,116,388		$	—		$	1,116,388		$	983,673	$	—	$	983,673
	Less: Current Portion of Long-Term Debt		4,685			—			4,685			4,591		—		4,591
	Total Long-Term Debt		$	1,111,703		$	—		$	1,111,703		$	979,082	$	—	$	979,082
	-1	The recorded value of the Amended Credit Facility approximates its fair value due to its floating rate structure.
	-2	The aggregate estimated fair value of the Convertible Notes was approximately $25.3 million and $25.1 million as of June 30, 2014 and December 31, 2013, respectively, based on reported market trades of these instruments.
	-3	The Company has the right at any time, with at least 30 days' notice, to call the Convertible Notes, and the holders have the right to require the Company to purchase the notes on each of March 20, 2015, March 20, 2018 and March 20, 2023.
	-4	The aggregate estimated fair value of the 7.625% Senior Notes was approximately $430.1 million and $430.2 million as of June 30, 2014 and December 31, 2013, respectively, based on reported market trades of these instruments.
	-5	The aggregate estimated fair value of the 7.0% Senior Notes was approximately $424.0 million and $417.0 million as of June 30, 2014 and December 31, 2013, respectively, based on reported market trades of these instruments.
	-6	The aggregate estimated fair value of the Lease Financing Obligation was approximately $39.4 million as of June 30, 2014, and $41.7 million as of December 31, 2013. 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.
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 9.875% Senior Notes that were redeemed in full on July 15, 2013, Convertible Notes, 7.625% Senior Notes, 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 June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
		(in thousands)
	Amended Credit Facility (1)
	Cash interest	$	1,543		$	1,051		$	2,621		$	1,915
	Non-cash interest	$	585		$	586		$	1,171		$	1,171
	9.875% Senior Notes (2)
	Cash interest	$	—		$	6,172		$	—		$	12,344
	Non-cash interest	$	—		$	682		$	—		$	1,361
	Convertible Notes (3)
	Cash interest	$	324		$	320		$	634		$	633
	Non-cash interest	$	2		$	1		$	3		$	3
	7.625% Senior Notes (4)
	Cash interest	$	7,625		$	7,625		$	15,250		$	15,250
	Non-cash interest	$	272		$	263		$	544		$	526
	7.0% Senior Notes (5)
	Cash interest	$	7,000		$	7,000		$	14,000		$	14,000
	Non-cash interest	$	203		$	194		$	406		$	389
	Lease Financing Obligation (6)
	Cash interest	$	255		$	768		$	517		$	1,555
	Non-cash interest	$	4		$	8		$	8		$	16
	-1	Cash interest includes amounts related to interest and commitment fees paid on the Amended Credit Facility and participation and fronting fees paid on the letter of credit.
	-2	The stated interest rate for the 9.875% Senior Notes was 9.875% per annum with an effective interest rate of 11.2% per annum. The Company redeemed the 9.875% Senior Notes in full on July 15, 2013.
	-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 $25.3 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 from $0.8 million to $0.3 million for the three months ended June 30, 2013 and June 30, 2014, respectively, and from $1.6 million to $0.5 million for the six months ended June 30, 2013 and June 30, 2014, respectively, is due to the West Tavaputs Divestiture. The purchaser assumed approximately 51% of the Lease Financing Obligation, including the buyout option, related to West Tavaputs equipment, leaving the Company with a balance of $41.0 million as of June 30, 2014.

Asset_Retirement_Obligations_T

Asset Retirement Obligations (Tables)	6 Months Ended
	Jun. 30, 2014
Asset Retirement Obligation Disclosure [Abstract]	'
Schedule of Asset Retirement Obligations	'
	A reconciliation of the Company's asset retirement obligations for the six months ended June 30, 2014 is as follows (in thousands):
	As of December 31, 2013	$	43,005
	Liabilities incurred	2,045
	Liabilities settled	(1,247		)
	Disposition of properties	—
	Accretion expense	1,658
	Revisions to estimate	1,150
	As of June 30, 2014	$	46,611
	Less: Current asset retirement obligations	6,168
	Long-term asset retirement obligations	$	40,443

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2014
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 June 30, 2014
		Level 1		Level 2		Level 3		Total
		(in thousands)
	Assets
	Deferred Compensation Plan	$	785	$	—	$	—	$	785
	Cash Equivalents - Money Market Funds	53		—		—		53
	Commodity Derivatives	—		4,461		—		4,461
	Liabilities
	Commodity Derivatives	$	—	$	61,690	$	—	$	61,690
		As of December 31, 2013
		Level 1		Level 2		Level 3		Total
		(in thousands)
	Assets
	Deferred Compensation Plan	$	941	$	—	$	—	$	941
	Cash Equivalents - Money Market Funds	53		—		—		53
	Commodity Derivatives	—		11,483		—		11,483
	Liabilities
	Commodity Derivatives	$	—	$	14,771	$	—	$	14,771

Derivative_Instruments_Tables

Derivative Instruments (Tables)	6 Months Ended
	Jun. 30, 2014
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 June 30, 2014
	Balance Sheet	Gross Amounts of				Gross Amounts				Net Amounts of Derivative
		Recognized				Offset in the Balance				Assets Presented in the
		Derivative Assets				Sheet				Balance Sheet
		(in thousands)
	Derivative assets	$	3,411			$	(3,411	)	(1)	$	—
	Deferred financing costs and other noncurrent assets	1,050				(1,050		)	(1)	—			(3)
	Total derivative assets	$	4,461			$	(4,461	)		$	—
		Gross Amounts of				Gross Amounts				Net Amounts of Derivative
		Recognized				Offset in the Balance				Liabilities Presented in
		Derivative				Sheet				the Balance Sheet
		Liabilities
		(in thousands)
	Derivative liabilities	$	(44,790	)		$	3,411		(1)	$	(41,379	)
	Derivatives and other noncurrent liabilities	(16,900		)		1,050			(1)	(15,850		)	(4)
	Total derivative liabilities	$	(61,690	)		$	4,461			$	(57,229	)
		As of December 31, 2013
	Balance Sheet	Gross Amounts of				Gross Amounts				Net Amounts of Derivative
		Recognized				Offset in the Balance				Assets Presented in the
		Derivative Assets				Sheet				Balance Sheet
		(in thousands)
	Derivative assets	$	8,259			$	(8,086	)	(2)	$	173
	Deferred financing costs and other noncurrent assets	3,224				(685		)	(2)	2,539			(3)
	Total derivative assets	$	11,483			$	(8,771	)		$	2,712
		Gross Amounts of				Gross Amounts				Net Amounts of Derivative
		Recognized				Offset in the Balance				Liabilities Presented in
		Derivative				Sheet				the Balance Sheet
		Liabilities
		(in thousands)
	Derivative liabilities	$	(14,074	)		$	8,086		(1)	$	(5,988	)
	Derivatives and other noncurrent liabilities	(697		)		685			(1)	(12		)	(4)
	Total derivative liabilities	$	(14,771	)		$	8,771			$	(6,000	)
	-1	Derivative asset balances are netted against derivative liability balances with the same counterparty, and therefore are presented as a net liability in the Unaudited Consolidated Balance Sheets.
	-2	Derivative liability balances are netted against derivative asset balances with the same counterparty, and therefore are presented as a net asset in the Unaudited Consolidated Balance Sheets.
	-3	As of June 30, 2014 and December 31, 2013, this line item in the Unaudited Consolidated Balance Sheets included $17.4 million and $19.2 million of deferred financing costs and other noncurrent assets, respectively.
	-4	As of June 30, 2014 and December 31, 2013, this line item in the Unaudited Consolidated Balance Sheets included $3.0 million and $3.5 million of other noncurrent liabilities, respectively.
Cash Flow Hedge Gains and Losses	'
	The following table summarizes the cash flow hedge gains, net of tax, as of the periods indicated:
	Derivatives Qualifying as Cash Flow Hedges			Three Months Ended June 30,								Six Months Ended June 30,
				2014				2013				2014				2013
				(in thousands)
	Amount of gain reclassified from AOCI into income (net of tax) (1)(2)	Commodity Hedges		$	239			$	1,210			$	336			$	2,502
	-1	Gains reclassified from accumulated other comprehensive income ("AOCI") into income are included in the oil, gas and NGL production revenues in the Unaudited Consolidated Statements of Operations.
	-2	Presented net of income tax expense of $0.1 million and $0.7 million for the three months ended June 30, 2014 and 2013, respectively, and $0.2 million and $1.5 million for the six months ended June 30, 2014 and 2013, respectively.
Financial Instruments for Hedging Volumes	'
	As of June 30, 2014, 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:
		July – December			For the year			For the  year			For the  year
		2014			2015			2016			2017
	Oil (Bbls)	1,950,400			4,077,500			1,554,000			182,500
	Natural gas (MMbtu)	12,570,000			7,300,000			1,830,000			—
	Natural gas liquids (Bbls)	189,286			—			—			—
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 June 30,								Six Months Ended June 30,
		2014				2013				2014				2013
		(in thousands)
	Commodity derivative gain settlements on derivatives designated as cash flow hedges (1)	$	382			$	1,936			$	538			$	4,003
	Total commodity derivative gain (loss) (2)	(46,775		)		36,839				(71,930		)		6,988
	-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_Compensation_1

Equity Incentive Compensation Plans and Other Employee Benefits (Tables)	6 Months Ended
	Jun. 30, 2014
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 June 30,						Six Months Ended June 30,
		2014			2013			2014				2013
		(in thousands)
	Common stock options	$	497		$	727		$	1,126			$	3,217
	Nonvested equity common stock	1,548			1,588			3,219				3,988
	Nonvested equity common stock units	260			312			509				712
	Nonvested performance-based equity	146			530			964				698
	Total	$	2,451		$	3,157		$	5,818			$	8,615
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 June 30, 2014					Three Months Ended June 30, 2013
		Number of		Weighted Average			Number of			Weighted Average
		Shares		Grant Date Fair			Shares			Grant Date Fair
				Value Per Share						Value Per Share
	Nonvested equity common stock	23,626		$	23.91		16,880			$	19.54
	Nonvested equity common stock units	700		$	26.78		43,824			$	22.38
	Nonvested performance-based equity shares	44,540		$	20.92		13,007			$	17.26
	Total shares granted	68,866					73,711
		Six Months Ended June 30, 2014					Six Months Ended June 30, 2013
		Number of		Weighted Average			Number of			Weighted Average
		Shares		Grant Date Fair			Shares			Grant Date Fair
				Value Per Share						Value Per Share
	Nonvested equity common stock	489,940		$	22.54		557,260			$	17.32
	Nonvested equity common stock units	1,432		$	26.18		52,219			$	22.04
	Nonvested performance-based equity shares	293,115		$	19.81		287,986			$	16.6
	Total shares granted	784,487					897,465

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2014
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 June 30, 2014
		(in thousands)
	2014	$	2,990
	2015	5,979
	2016	5,979
	2017	5,979
	2018	5,979
	Thereafter	18,781
	Total	$	45,687
Gross Future Minimum Transportation Demand and Firm Processing Charges	'
	The amounts in the table below represent the Company's gross future minimum transportation charges. However, the Company will record in its financial statements only the Company's proportionate share based on the Company's working interest and net revenue interest, which will vary from property to property. From time to time, we may sell certain portions of firm capacity on various pipelines, as business or operations conditions warrant, to mitigate our exposure on unused transportation capacity.
		As of June 30, 2014
		(in thousands)
	2014	$	18,254
	2015	36,717
	2016	35,466
	2017	33,085
	2018	33,521
	Thereafter	63,813
	Total	$	220,856
Future Minimum Annual Payments Under Drilling, Lease and Other Agreements	'
	Future minimum annual payments under lease and other agreements are as follows:
		As of June 30, 2014
		(in thousands)
	2014	$	1,934
	2015 (1)	9,939
	2016	2,713
	2017	2,540
	2018	2,528
	Thereafter	633
	Total	$	20,287
	-1	Includes a drilling carry in the amount of $8.5 million from a purchase, sale and exploration agreement related to acreage in the Powder River Basin. As of June 30, 2014, the Company has satisfied $1.7 million of this carry. The Company will owe the remaining carry balance if not satisfied by October 1, 2015.

Guarantor_Subsidiaries_Tables

Guarantor Subsidiaries (Tables)	6 Months Ended
	Jun. 30, 2014
Text Block [Abstract]	'
Schedule of Condensed Consolidating Balance Sheets	'
	Condensed Consolidating Balance Sheets
		As of June 30, 2014
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Assets:
	Current assets	$	165,929		$	52		$	—		$	165,981
	Property and equipment, net	2,275,639			75,317			—			2,350,956
	Intercompany receivable (payable)	52,927			(52,927		)	—			—
	Investment in subsidiaries	16,315			—			(16,315		)	—
	Noncurrent assets	17,375			—			—			17,375
	Total assets	$	2,528,185		$	22,442		$	(16,315	)	$	2,534,312
	Liabilities and Stockholders' Equity:
	Current liabilities	$	236,722		$	1,247		$	—		$	237,969
	Long-term debt	1,111,703			—			—			1,111,703
	Deferred income taxes	151,463			3,255			—			154,718
	Other noncurrent liabilities	57,702			1,625			—			59,327
	Stockholders' equity	970,595			16,315			(16,315		)	970,595
	Total liabilities and stockholders' equity	$	2,528,185		$	22,442		$	(16,315	)	$	2,534,312
		As of December 31, 2013
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Assets:
	Current assets	$	154,986		$	2,261		$	—		$	157,247
	Property and equipment, net	2,127,624			74,872			—			2,202,496
	Intercompany receivable (payable)	59,076			(59,076		)	—			—
	Investment in subsidiaries	12,063			—			(12,063		)	—
	Noncurrent assets	21,770			—			—			21,770
	Total assets	$	2,375,519		$	18,057		$	(12,063	)	$	2,381,513
	Liabilities and Stockholders' Equity:
	Current liabilities	$	192,106		$	613		$	—		$	192,719
	Long-term debt	979,082			—			—			979,082
	Deferred income taxes	158,071			3,255			—			161,326
	Other noncurrent liabilities	40,542			2,126			—			42,668
	Stockholders' equity	1,005,718			12,063			(12,063		)	1,005,718
	Total liabilities and stockholders' equity	$	2,375,519		$	18,057		$	(12,063	)	$	2,381,513
Schedule of Condensed Consolidating Statements of Operations	'
	Condensed Consolidating Statements of Operations
		Three Months Ended June 30, 2014
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Operating and other revenues	$	138,355		$	6,653		$	—		$	145,008
	Operating expenses	(99,809		)	(4,264		)	—			(104,073		)
	General and administrative	(14,521		)	—			—			(14,521		)
	Interest income and other income (expense)	(64,279		)	35			—			(64,244		)
	Income (loss) before income taxes and equity in earnings of subsidiaries	(40,254		)	2,424			—			(37,830		)
	Benefit from income taxes	11,244			—			—			11,244
	Equity in earnings of subsidiaries	2,424			—			(2,424		)	—
	Net income (loss)	$	(26,586	)	$	2,424		$	(2,424	)	$	(26,586	)
		Six Months Ended June 30, 2014
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Operating and other revenues	$	260,038		$	12,658		$	—		$	272,696
	Operating expenses	(188,696		)	(8,441		)	—			(197,137		)
	General and administrative	(29,928		)	—			—			(29,928		)
	Interest income and other income (expense)	(106,490		)	35			—			(106,455		)
	Income (loss) before income taxes and equity in earnings of subsidiaries	(65,076		)	4,252			—			(60,824		)
	Benefit from income taxes	21,489			—			—			21,489
	Equity in earnings (loss) of subsidiaries	4,252			—			(4,252		)	—
	Net income (loss)	$	(39,335	)	$	4,252		$	(4,252	)	$	(39,335	)
		Three Months Ended June 30, 2013
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Operating and other revenues	$	142,298		$	1		$	—		$	142,299
	Operating expenses	(118,295		)	—			—			(118,295		)
	General and administrative	(13,273		)	—			—			(13,273		)
	Interest and other income (expense)	12,145			—			—			12,145
	Income before income taxes and equity in earnings of subsidiaries	22,875			1			—			22,876
	Provision for income taxes	(8,603		)	—			—			(8,603		)
	Equity in earnings of subsidiaries	1			—			(1		)	—
	Net income (loss)	$	14,273		$	1		$	(1	)	$	14,273
		Six Months Ended June 30, 2013
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Operating and other revenues	$	280,576		$	—		$	—		$	280,576
	Operating expenses	(234,214		)	—			—			(234,214		)
	General and administrative	(33,855		)	—			—			(33,855		)
	Interest and other income (expense)	(42,209		)	—			—			(42,209		)
	Income (loss) before income taxes and equity in earnings of subsidiaries	(29,702		)	—			—			(29,702		)
	Benefit from income taxes	10,824			—			—			10,824
	Equity in earnings (loss) of subsidiaries	—			—			—			—
	Net income (loss)	$	(18,878	)	$	—		$	—		$	(18,878	)
Schedule of Condensed Consolidating Statements of Comprehensive Income (Loss)	'
	Condensed Consolidating Statements of Comprehensive Income (Loss)
		Three Months Ended June 30, 2014
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Net income (loss)	$	(26,586	)	$	2,424		$	(2,424	)	$	(26,586	)
	Other Comprehensive Loss, net of tax:
	Effect of derivative financial instruments	(239		)	—			—			(239		)
	Other comprehensive loss	(239		)	—			—			(239		)
	Comprehensive income (loss)	$	(26,825	)	$	2,424		$	(2,424	)	$	(26,825	)
		Six Months Ended June 30, 2014
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Net income (loss)	$	(39,335	)	$	4,252		$	(4,252	)	$	(39,335	)
	Other Comprehensive Loss, net of tax:
	Effect of derivative financial instruments	(336		)	—			—			(336		)
	Other comprehensive loss	(336		)	—			—			(336		)
	Comprehensive income (loss)	$	(39,671	)	$	4,252		$	(4,252	)	$	(39,671	)
		Three Months Ended June 30, 2013
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Net income (loss)	$	14,273		$	1		$	(1	)	$	14,273
	Other Comprehensive Loss, net of tax:
	Effect of derivative financial instruments	(1,210		)	—			—			(1,210		)
	Other comprehensive loss	(1,210		)	—			—			(1,210		)
	Comprehensive income (loss)	$	13,063		$	1		$	(1	)	$	13,063
		Six Months Ended June 30, 2013
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Net income (loss)	$	(18,878	)	$	—		$	—		$	(18,878	)
	Other Comprehensive Loss, net of tax:
	Effect of derivative financial instruments	(2,502		)	—			—			(2,502		)
	Other comprehensive loss	(2,502		)	—			—			(2,502		)
	Comprehensive income (loss)	$	(21,380	)	$	—		$	—		$	(21,380	)
Schedule of Condensed Consolidating Statements of Cash Flows	'
	Condensed Consolidating Statements of Cash Flows
		Six Months Ended June 30, 2014
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Cash flows from operating activities	$	115,705		$	11,713		$	—		$	127,418
	Cash flows from investing activities:
	Additions to oil and gas properties, including acquisitions	(257,471		)	(6,874		)	—			(264,345		)
	Additions to furniture, fixtures and other	(856		)	—			—			(856		)
	Proceeds from sale of properties and other investing activities	7,640			535			—			8,175
	Intercompany transfers	5,374			—			(5,374		)	—
	Cash flows from financing activities:
	Proceeds from debt	135,000			—			—			135,000
	Principal payments on debt	(2,285		)	—			—			(2,285		)
	Intercompany transfers	—			(5,374		)	5,374			—
	Other financing activities	(1,923		)	—			—			(1,923		)
	Change in cash and cash equivalents	1,184			—			—			1,184
	Beginning cash and cash equivalents	54,545			50			—			54,595
	Ending cash and cash equivalents	$	55,729		$	50		$	—		$	55,779
		Six Months Ended June 30, 2013
		Parent			Guarantor			Intercompany			Consolidated
		Issuer			Subsidiaries			Eliminations
		(in thousands)
	Cash flows from operating activities	$	117,209		$	5,820		$	—		$	123,029
	Cash flows from investing activities:
	Additions to oil and gas properties, including acquisitions	(204,020		)	(12,632		)	—			(216,652		)
	Additions to furniture, fixtures and other	731			(1,918		)	—			(1,187		)
	Proceeds from sale of properties and other investing activities	4,086			—			—			4,086
	Cash flows from financing activities:
	Proceeds from debt	80,000			—			—			80,000
	Principal payments on debt	(4,501		)	—			—			(4,501		)
	Intercompany transfers	(5,546		)	5,546			—			—
	Other financing activities	(1,345		)	—			—			(1,345		)
	Change in cash and cash equivalents	(13,386		)	(3,184		)	—			(16,570		)
	Beginning cash and cash equivalents	79,395			50			—			79,445
	Ending cash and cash equivalents	$	66,009		$	(3,134	)	$	—		$	62,875

Summary_of_Significant_Account3

Summary of Significant Accounting Policies - Additional Information (Detail) (5% Convertible Senior Notes Due 2028)	Jun. 30, 2014
5% Convertible Senior Notes Due 2028	'
Summary Of Significant Accounting Policies [Line Items]	'
Debt, stated interest rate	5.00%

Summary_of_Significant_Account4

Summary of Significant Accounting Policies - Summary of Accounts Receivable (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Allowance for doubtful accounts	($21)	($21)
Accounts receivable	91,880	97,586
Accrued Oil, Gas, and NGL Sales	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Accounts receivable gross	61,381	67,583
Due from Joint Interest Owners	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Accounts receivable gross	23,890	23,507
Other	'	'
Accounts, Notes, Loans and Financing Receivable [Line Items]	'	'
Accounts receivable gross	$6,630	$6,517

Summary_of_Significant_Account5

Summary of Significant Accounting Policies - Net Capitalized Costs and Associated Accumulated Depreciation, Depletion & Amortization and Non Cash Impairments (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounting Policies [Abstract]	'	'
Proved properties	$494,371	$485,427
Wells and related equipment and facilities	2,421,552	2,192,754
Support equipment and facilities	180,421	177,224
Materials and supplies	10,961	8,518
Total proved oil and gas properties	3,107,305	2,863,923
Unproved properties	212,623	239,925
Wells and facilities in progress	86,849	56,674
Total unproved oil and gas properties, excluded from amortization	299,472	296,599
Accumulated depreciation, depletion, amortization and impairment	-1,072,804	-976,339
Total oil and gas properties, net	$2,333,973	$2,184,183

Summary_of_Significant_Account6

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 $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Summary Of Significant Accounting Policies [Line Items]	'	'	'	'
Dry hole costs	($12)	$113	$94	$964
Abandonment expense	1,415	1,069	2,032	7,319
Impairment, dry hole costs and abandonment expense	1,743	1,182	3,504	8,283
Proved Oil And Gas Properties [Member]	'	'	'	'
Summary Of Significant Accounting Policies [Line Items]	'	'	'	'
Non-cash impairment of oil and gas properties	0	0	1,038	0
Unproved Oil And Gas Properties [Member]	'	'	'	'
Summary Of Significant Accounting Policies [Line Items]	'	'	'	'
Non-cash impairment of oil and gas properties	0	0	0	0
Non Cash Impairment Of Inventory [Member]	'	'	'	'
Summary Of Significant Accounting Policies [Line Items]	'	'	'	'
Non-cash impairment of inventory	$340	$0	$340	$0

Summary_of_Significant_Account7

Summary of Significant Accounting Policies - Accounts Payable and Accrued Liabilities (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accounting Policies [Abstract]	'	'
Accrued drilling, completion and facility costs	$80,132	$54,750
Accrued lease operating, gathering, transportation and processing expenses	12,791	17,317
Accrued general and administrative expenses	8,504	14,605
Trade payables and other	22,866	29,256
Total accounts payable and accrued liabilities	$124,293	$115,928

Summary_of_Significant_Account8

Summary of Significant Accounting Policies - Calculation of Basic and Diluted Earnings (Loss) Per Share (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Accounting Policies [Abstract]	'	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	1,120,210	2,857,757	1,257,716	2,836,480	'
Net Income (Loss)	($26,586)	$14,273	($39,335)	($18,878)	($192,733)
Basic weighted-average common shares outstanding in period	47,996,816	47,468,569	47,943,806	47,411,054	'
Add dilutive effects of stock options and nonvested equity shares of common stock	0	147,000	0	0	'
Diluted weighted-average common shares outstanding in period	47,996,816	47,615,871	47,943,806	47,411,054	'
Net Income (Loss) Per Common Share, Basic (in dollars per share)	($0.55)	$0.30	($0.82)	($0.40)	'
Net Income (Loss) Per Common Share, Diluted (in dollars per share)	($0.55)	$0.30	($0.82)	($0.40)	'

Supplemental_Disclosures_of_Ca2

Supplemental Disclosures of Cash Flow Information - Supplemental Cash Flow Information (Detail) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Supplemental Cash Flow Information [Abstract]	'	'
Cash paid for interest, net of amount capitalized	$33,173	$45,709
Cash paid for income taxes	1	1,861
Supplemental disclosures of non-cash investing and financing activities:	'	'
Current liabilities	82,782	68,731
Net increase in asset retirement obligations	3,195	1,888
Retirement of treasury stock	($2,049)	($1,337)

Divestitures_Details

Divestitures (Details) (West Tavaputs [Member], USD $)	3 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
West Tavaputs [Member]	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'
Proceeds from sale of businesses	'	$308,700,000
Impairment loss recognized	$1,000,000	$209,500,000

LongTerm_Debt_Outstanding_Debt

Long-Term Debt - Outstanding Debt (Detail) (USD $)

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Mar. 31, 2012

Jun. 30, 2014

Dec. 31, 2013

Sep. 27, 2011

Jun. 30, 2014

Dec. 31, 2013

Mar. 12, 2012

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Amended Credit Facility

Amended Credit Facility

Convertible Notes

Convertible Notes

Convertible Notes

7.625% Senior Notes

7.625% Senior Notes

7.625% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

Lease Financing Obligation

Lease Financing Obligation

Long-term Debt

Long-term Debt

Current Portion of Long-Term Debt

Current Portion of Long-Term Debt

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maturity Date

'

'

31-Oct-16

'

15-Mar-28

'

'

1-Oct-19

'

'

15-Oct-22

'

'

10-Aug-20

'

'

'

'

'

Principal amount of debt instrument

$1,111,703,000

$979,082,000

$250,000,000

$115,000,000

$25,344,000

$25,344,000

$25,300,000

$400,000,000

$400,000,000

$400,000,000

$400,000,000

$400,000,000

$400,000,000

$41,044,000

$43,329,000

$1,116,388,000

$983,673,000

$4,685,000

$4,591,000

Discount

0

0

0

0

0

0

'

0

0

'

0

0

'

0

0

0

0

0

0

Carrying Amount

1,111,703,000

979,082,000

250,000,000

115,000,000

25,344,000

25,344,000

'

400,000,000

400,000,000

'

400,000,000

400,000,000

'

41,044,000

43,329,000

1,116,388,000

983,673,000

4,685,000

4,591,000

Aggregate fair value of convertible notes

'

'

'

'

25,300,000

25,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt, stated interest rate

'

'

'

'

5.00%

'

'

7.63%

7.63%

'

7.00%

7.00%

'

'

'

'

'

'

'

Debt, fair value

$854,100,000

$847,200,000

$250,000,000

$115,000,000

$25,300,000

$25,100,000

'

$430,100,000

$430,200,000

'

$424,000,000

$417,000,000

'

$39,400,000

$41,700,000

'

'

'

'

LongTerm_Debt_LongTerm_Debt_Ad

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

3 Months Ended

6 Months Ended

6 Months Ended

1 Months Ended

6 Months Ended

0 Months Ended

6 Months Ended

6 Months Ended

1 Months Ended

6 Months Ended

6 Months Ended

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Mar. 20, 2012

Jun. 30, 2014

Mar. 12, 2008

Jun. 30, 2014

Dec. 31, 2013

Mar. 31, 2012

Sep. 27, 2011

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2013

Mar. 12, 2012

Jul. 23, 2012

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Amended Credit Facility

Amended Credit Facility

5% Convertible Senior Notes

5% Convertible Senior Notes

5% Convertible Senior Notes

Convertible Notes

Convertible Notes

Convertible Notes

7.625% Senior Notes

7.625% Senior Notes

7.625% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

Lease Financing Obligation

Lease Financing Obligation

Lease Financing Obligation

9.875% Senior Notes

Minimum

Maximum

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt instrument, maturity date

'

'

'

'

'

31-Oct-16

'

'

'

'

15-Mar-28

'

'

'

1-Oct-19

'

15-Oct-22

'

'

'

10-Aug-20

'

'

'

'

Line of credit facility, maximum borrowing capacity

$625,000,000

'

$625,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Revolving credit facility, interest rate above London Interbank Offered Rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.50%

2.50%

Revolving credit facility interest rate percent above LIBOR alternate interest rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.50%

1.50%

Commitment fee percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.38%

0.50%

Average annual interest rates incurred on Amended Credit Facility

1.90%

1.70%

1.80%

1.70%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit facility, amount outstanding during period

'

'

'

'

'

250,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Letters of credit issued amount

'

'

'

'

'

26,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of credit facility, remaining borrowing capacity

349,000,000

'

349,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Principal amount

1,111,703,000

'

1,111,703,000

'

979,082,000

250,000,000

115,000,000

'

'

172,500,000

25,344,000

25,344,000

25,300,000

400,000,000

400,000,000

400,000,000

400,000,000

400,000,000

400,000,000

'

41,044,000

43,329,000

'

'

'

Face Amount of Outstanding Convertible Notes Repaid

'

'

'

'

'

'

'

147,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage of notes put to company

'

'

'

'

'

'

'

85.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt, stated interest rate

'

'

'

'

'

'

'

'

5.00%

'

5.00%

'

'

'

7.63%

7.63%

7.00%

7.00%

'

'

'

'

9.88%

'

'

Sale and subsequent lease back

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100,800,000

'

'

'

'

'

Par value of senior notes

'

'

'

'

'

'

'

'

'

'

'

'

'

103.81%

'

'

103.50%

'

'

'

'

'

'

'

'

Debt instrument conversion price rate of redemption

'

'

'

'

'

'

'

'

'

'

100.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Minimum days notice to call Convertible Notes

'

'

'

'

'

'

'

'

'

'

'30 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Purchase of equipment

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$36,600,000

'

'

'

'

Weighted average implicit rate based on interest expense

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3.30%

'

'

'

'

Percent Of Financing Obligation Sold

51.00%

'

51.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

LongTerm_Debt_Cash_and_NonCash

Long-Term Debt - Cash and Non-Cash Portion of Interest Expense Related to Long Term Debt (Detail) (USD $)

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Dec. 31, 2013

Mar. 31, 2012

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Dec. 31, 2013

Sep. 27, 2011

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Dec. 31, 2013

Mar. 12, 2012

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jul. 23, 2012

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

9.875% Senior Notes

9.875% Senior Notes

9.875% Senior Notes

9.875% Senior Notes

9.875% Senior Notes

9.875% Senior Notes

9.875% Senior Notes

9.875% Senior Notes

9.875% Senior Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

Convertible Notes

7.625% Senior Notes

7.625% Senior Notes

7.625% Senior Notes

7.625% Senior Notes

7.625% Senior Notes

7.625% Senior Notes

7.625% Senior Notes

7.625% Senior Notes

7.625% Senior Notes

7.625% Senior Notes

7.625% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

7.0% Senior Notes

Lease Financing Obligation

Lease Financing Obligation

Lease Financing Obligation

Lease Financing Obligation

Lease Financing Obligation

Lease Financing Obligation

Lease Financing Obligation

Lease Financing Obligation

Lease Financing Obligation

Lease Financing Obligation

Lease Financing Obligation

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Non-cash interest [Member]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Amended Credit Facility interest

'

'

$1,543,000

$1,051,000

$2,621,000

$1,915,000

$585,000

$586,000

$1,171,000

$1,171,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Senior Notes interest

'

'

'

'

'

'

'

'

'

'

'

0

6,172,000

0

12,344,000

0

682,000

0

1,361,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7,625,000

7,625,000

15,250,000

15,250,000

272,000

263,000

544,000

526,000

'

'

'

7,000,000

7,000,000

14,000,000

14,000,000

203,000

194,000

406,000

389,000

'

'

'

'

'

'

'

'

'

'

'

Convertible Notes interest

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

324,000

320,000

634,000

633,000

2,000

1,000

3,000

3,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Financial Obligation interest

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

255,000

768,000

517,000

1,555,000

4,000

8,000

8,000

16,000

Debt, stated interest rate

'

'

'

'

'

'

'

'

'

'

9.88%

'

'

'

'

'

'

'

'

5.00%

'

'

'

'

'

'

'

'

'

'

7.63%

7.63%

'

'

'

'

'

'

'

'

'

7.00%

7.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Effective interest rate of debt instrument

'

'

'

'

'

'

'

'

'

'

11.20%

'

'

'

'

'

'

'

'

5.00%

'

'

'

'

'

'

'

'

'

'

8.00%

'

'

'

'

'

'

'

'

'

'

7.20%

'

'

'

'

'

'

'

'

'

'

'

3.30%

'

'

'

'

'

'

'

'

'

Principal amount of debt instrument

1,111,703,000

979,082,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

25,344,000

25,344,000

25,300,000

'

'

'

'

'

'

'

'

400,000,000

400,000,000

400,000,000

'

'

'

'

'

'

'

'

400,000,000

400,000,000

400,000,000

'

'

'

'

'

'

'

'

'

41,044,000

43,329,000

'

'

'

'

'

'

'

'

Percent of Financing Obligation held-for-sale

51.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Sale and subsequent lease back

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$100,800,000

'

'

'

'

'

'

'

'

'

'

Asset_Retirement_Obligations_S

Asset Retirement Obligations - Schedule of Asset Retirement Obligations (Detail) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]	'
As of December 31, 2013	$43,005
Liabilities incurred	2,045
Liabilities settled	-1,247
Disposition of properties	0
Accretion expense	1,658
Revisions to estimate	1,150
As of June 30, 2014	46,611
Less: Current asset retirement obligations	6,168
Long-term asset retirement obligations	$40,443

Fair_Value_Measurements_Fair_V

Fair Value Measurements - Fair Value, Balance Sheet Grouping (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assets	'	'	'	'
Deferred Compensation Plan	$785	$941	'	'
Cash Equivalents	55,779	54,595	62,875	79,445
Cash Equivalents - Money Market Funds	'	'	'	'
Assets	'	'	'	'
Cash Equivalents	53	53	'	'
Commodity Derivatives	'	'	'	'
Assets	'	'	'	'
Commodity Derivatives	4,461	11,483	'	'
Liabilities	'	'	'	'
Commodity Derivatives	61,690	14,771	'	'
Level 1	'	'	'	'
Assets	'	'	'	'
Deferred Compensation Plan	785	941	'	'
Level 1 | Cash Equivalents - Money Market Funds	'	'	'	'
Assets	'	'	'	'
Cash Equivalents	53	53	'	'
Level 1 | Commodity Derivatives	'	'	'	'
Assets	'	'	'	'
Commodity Derivatives	0	0	'	'
Liabilities	'	'	'	'
Commodity Derivatives	0	0	'	'
Level 2	'	'	'	'
Assets	'	'	'	'
Deferred Compensation Plan	0	0	'	'
Level 2 | Cash Equivalents - Money Market Funds	'	'	'	'
Assets	'	'	'	'
Cash Equivalents	0	0	'	'
Level 2 | Commodity Derivatives	'	'	'	'
Assets	'	'	'	'
Commodity Derivatives	4,461	11,483	'	'
Liabilities	'	'	'	'
Commodity Derivatives	61,690	14,771	'	'
Level 3	'	'	'	'
Assets	'	'	'	'
Deferred Compensation Plan	0	0	'	'
Level 3 | Cash Equivalents - Money Market Funds	'	'	'	'
Assets	'	'	'	'
Cash Equivalents	0	0	'	'
Level 3 | Commodity Derivatives	'	'	'	'
Assets	'	'	'	'
Commodity Derivatives	0	0	'	'
Liabilities	'	'	'	'
Commodity Derivatives	$0	$0	'	'

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Fair Value Measurements [Line Items]	'	'
Debt, fair value	$854.10	$847.20
7.625% Senior Notes	'	'
Fair Value Measurements [Line Items]	'	'
Debt, stated interest rate	7.63%	7.63%
Debt, fair value	430.1	430.2
7.0% Senior Notes	'	'
Fair Value Measurements [Line Items]	'	'
Debt, stated interest rate	7.00%	7.00%
Debt, fair value	424	417
Amended Credit Facility	'	'
Fair Value Measurements [Line Items]	'	'
Debt, fair value	250	115
Convertible Notes	'	'
Fair Value Measurements [Line Items]	'	'
Debt, stated interest rate	5.00%	'
Debt, fair value	25.3	25.1
Lease Financing Obligation	'	'
Fair Value Measurements [Line Items]	'	'
Debt, fair value	$39.40	$41.70

Derivative_Instruments_Fair_Va

Derivative Instruments - Fair Value Amounts of Derivative Instruments (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]	'	'
Gross Amounts of Recognized Derivative Assets	$4,461,000	$11,483,000
Gross Amounts Offset in the Balance Sheet	-4,461,000	-8,771,000
Net Amounts of Derivative Assets Presented in the Balance Sheet	0	2,712,000
Gross Amounts of Recognized Derivative Liabilities	-61,690,000	-14,771,000
Gross Amounts Offset in the Balance Sheet	4,461,000	8,771,000
Net Amounts of Derivative Liabilities Presented in the Balance Sheet	-57,229,000	-6,000,000
Balance included in other noncurrent liabilities excluding deferred financing costs and other noncurrent assets	17,400,000	19,200,000
Derivative assets	'	'
Derivatives, Fair Value [Line Items]	'	'
Gross Amounts of Recognized Derivative Assets	3,411,000	8,259,000
Gross Amounts Offset in the Balance Sheet	-3,411,000	-8,086,000
Net Amounts of Derivative Assets Presented in the Balance Sheet	0	173,000
Deferred financing costs and other noncurrent assets	'	'
Derivatives, Fair Value [Line Items]	'	'
Gross Amounts of Recognized Derivative Assets	1,050,000	3,224,000
Gross Amounts Offset in the Balance Sheet	-1,050,000	-685,000
Net Amounts of Derivative Assets Presented in the Balance Sheet	0	2,539,000
Derivative liabilities	'	'
Derivatives, Fair Value [Line Items]	'	'
Gross Amounts of Recognized Derivative Liabilities	-44,790,000	-14,074,000
Gross Amounts Offset in the Balance Sheet	3,411,000	8,086,000
Net Amounts of Derivative Liabilities Presented in the Balance Sheet	-41,379,000	-5,988,000
Derivative Financial Instruments, Liabilities	'	'
Derivatives, Fair Value [Line Items]	'	'
Balance included in other noncurrent liabilities excluding hedge instruments	3,000,000	3,500,000
Derivatives and other noncurrent liabilities	'	'
Derivatives, Fair Value [Line Items]	'	'
Gross Amounts of Recognized Derivative Liabilities	-16,900,000	-697,000
Gross Amounts Offset in the Balance Sheet	1,050,000	685,000
Net Amounts of Derivative Liabilities Presented in the Balance Sheet	($15,850,000)	($12,000)

Derivative_Instruments_Cash_Fl

Derivative Instruments - Cash Flow Hedge Gain and Losses (Detail) (USD $)	6 Months Ended	12 Months Ended	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
			Commodity Derivatives	Commodity Derivatives	Commodity Derivatives	Commodity Derivatives
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'	'	'
Derivatives Qualifying as Cash Flow Hedges	'	'	'	'	'CommodityB Hedges	'
Amount of Gain (Loss) Reclassified from AOCI into Income (net of tax)	'	'	$239	$1,210	$336	$2,502
Effect of derivative financial instruments, taxes	$202	$2,802	$100	$700	$200	$1,500

Derivative_Instruments_Financi

Derivative Instruments - Financial Instruments for Hedging Volume (Detail)	Jun. 30, 2014
	MMBTU
	bbl
July b December 2014	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Oil (Bbls)	1,950,400
Natural gas (MMbtu)	12,570,000
Natural gas liquids (Bbls)	189,286
For the year 2015	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Oil (Bbls)	4,077,500
Natural gas (MMbtu)	7,300,000
Natural gas liquids (Bbls)	0
For the year 2016	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Oil (Bbls)	1,554,000
Natural gas (MMbtu)	1,830,000
Natural gas liquids (Bbls)	0
For the year 2017	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Oil (Bbls)	182,500
Natural gas (MMbtu)	0
Natural gas liquids (Bbls)	0

Derivative_Instruments_Realize

Derivative Instruments - Realized and Unrealized Gains and Losses on Commodity Derivative Instruments (Detail) (Oil and Natural Gas Derivative Instruments, USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Oil and Natural Gas Derivative Instruments	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Commodity Derivative Settlements On Derivatives Designated As Cash Flow Hedges	$382	$1,936	$538	$4,003
Total commodity derivative gain (loss)	($46,775)	$36,839	($71,930)	$6,988

Derivative_Instruments_Additio

Derivative Instruments - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2014
	Counterparty
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Number of counterparties for hedges at period end	9

Income_Taxes_Income_Taxes_Deta

Income Taxes Income Taxes (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014
Income Tax Disclosure [Abstract]	'	'
Effective tax rate	29.70%	35.30%

Equity_Incentive_Compensation_2

Equity Incentive Compensation Plans and Other Employee Benefits - Non-Cash Stock-Based Compensation Cost Related to Equity Awards (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Stock Based Compensation [Line Items]	'	'	'	'
Non-cash stock-based compensation equity awards	$2,451	$3,157	$5,818	$8,615
Common Stock Options	'	'	'	'
Stock Based Compensation [Line Items]	'	'	'	'
Non-cash stock-based compensation equity awards	497	727	1,126	3,217
Nonvested Equity Common Stock	'	'	'	'
Stock Based Compensation [Line Items]	'	'	'	'
Non-cash stock-based compensation equity awards	1,548	1,588	3,219	3,988
Nonvested Equity Common Stock Units	'	'	'	'
Stock Based Compensation [Line Items]	'	'	'	'
Non-cash stock-based compensation equity awards	260	312	509	712
Nonvested Performance-Based Equity	'	'	'	'
Stock Based Compensation [Line Items]	'	'	'	'
Non-cash stock-based compensation equity awards	$146	$530	$964	$698

Equity_Incentive_Compensation_3

Equity Incentive Compensation Plans and Other Employee Benefits - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		1 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Feb. 28, 2014	Feb. 28, 2014	Mar. 31, 2012
					2014 Performance Program	2014 Performance Program	2014 Performance Program
						Maximum	Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'	'	'	'
Unrecognized compensation cost	$24,100,000	'	$24,100,000	'	'	'	'
Weighted-average period (years)	'	'	'2 years 8 months 12 days	'	'	'	'
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%	'	'
Percentage Of Grant That Will Vest For Performance Met At Threshold Level	'	'	'	'	'	25.00%	'
Percentage of total grant that will vest for metrics met at target level	'	'	'	'	'	100.00%	'
Percentage of total grant that will vest for metrics met at stretch level	'	'	'	'	'	200.00%	200.00%
Non-cash stock based compensation	$2,451,000	$3,157,000	$5,818,000	$8,615,000	'	'	'

Equity_Incentive_Compensation_4

Equity Incentive Compensation Plans and Other Employee Benefits - Stock Options and Nonvested Equity Shares, Equity Awards Granted (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'	'	'	'
Nonvested equity shares, Number of Shares	23,626	16,880	489,940	557,260
Nonvested equity common stock units, Number of Shares	700	43,824	1,432	52,219
Nonvested performance-based equity shares, Number of Shares	44,540	13,007	293,115	287,986
Total shares granted	68,866	73,711	784,487	897,465
Nonvested equity shares, Weighted Average Grant Date Fair Value	$23.91	$19.54	$22.54	$17.32
Nonvested equity common stock units, Weighted Average Grant Date Fair Value	$26.78	$22.38	$26.18	$22.04
Nonvested performance-based equity shares, Weighted Average Grant Date Fair Value	$20.92	$17.26	$19.81	$16.60

Commitments_and_Contingencies_1

Commitments and Contingencies - Schedule of Aggregate Undiscounted Minimum Future Lease Payments (Detail) (Lease Financing Obligation, USD $)	Jun. 30, 2014
In Thousands, unless otherwise specified
Lease Financing Obligation	'
Future Minimum Lease Payments Under Capital Leases And Operating Leases For Continuing Operations [Line Items]	'
2014	$2,990
2015	5,979
2016	5,979
2017	5,979
2018	5,979
Thereafter	18,781
Total	$45,687

Commitments_and_Contingencies_2

Commitments and Contingencies - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
			Agreement
Contingencies And Commitments [Line Items]	'	'	'	'
Transportation Demand Charges	$7.40	$9.50	$15.10	$18
Firm processing charges	'	1.4	'	2
Number of take-or-pay purchase agreements for supply of carbon dioxide	'	'	1	'
Total financial commitment on take-or-pay purchase agreements for supply of carbon dioxide	1.7	'	'	'
Office lease expense	$0.30	$0.50	$0.70	$1
Minimum	'	'	'	'
Contingencies And Commitments [Line Items]	'	'	'	'
Contract term, years	'2 years	'	'	'
Maximum	'	'	'	'
Contingencies And Commitments [Line Items]	'	'	'	'
Contract term, years	'7 years	'	'	'

Commitments_and_Contingencies_3

Commitments and Contingencies - Gross Future Minimum Transportation Demand and Firm Processing Charges (Detail) (USD $)	Jun. 30, 2014
In Thousands, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]	'
2014	$18,254
2015	36,717
2016	35,466
2017	33,085
2018	33,521
Thereafter	63,813
Total	$220,856

Commitments_and_Contingencies_4

Commitments and Contingencies - Future Minimum Annual Payments under Drilling, Lease and Other Agreements (Detail) (Office & Equipment Leases, USD $)	Jun. 30, 2014
Operating Leased Assets [Line Items]	'
2014	$1,934,000
2015	9,939,000
2016	2,713,000
2017	2,540,000
2018	2,528,000
Thereafter	633,000
Total	20,287,000
Powder River Basin [Member] | Property Subject to Operating Lease [Member]	'
Operating Leased Assets [Line Items]	'
2015	8,500,000
Operating Leases, Carry Agreement, Amount Satisfied	$1,700,000

Guarantor_Subsidiaries_Additio

Guarantor Subsidiaries - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Dec. 31, 2013
		9.875% Senior Notes	7.625% Senior Notes	7.625% Senior Notes	7.0% Senior Notes	7.0% Senior Notes
Guarantor Subsidiaries [Line Items]	'	'	'	'	'	'
Debt, stated interest rate	'	9.88%	7.63%	7.63%	7.00%	7.00%
Percentage of Guarantor Subsidiaries	100.00%	'	'	'	'	'

Guarantor_Subsidiaries_Schedul

Guarantor Subsidiaries - Schedule of Condensed Consolidating Balance Sheets (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Assets:	'	'	'
Current assets	$165,981	$157,247	'
Property and equipment, net	2,350,956	2,202,496	'
Intercompany receivable (payable)	0	0	'
Investment in subsidiaries	0	0	'
Noncurrent assets	17,375	21,770	'
Total	2,534,312	2,381,513	'
Liabilities and Stockholders' Equity:	'	'	'
Current liabilities	237,969	192,719	'
Long-term debt	1,111,703	979,082	'
Deferred income taxes	154,718	161,326	'
Other noncurrent liabilities	59,327	42,668	'
Stockholders' equity	970,595	1,005,718	1,182,775
Total liabilities and stockholders' equity	2,534,312	2,381,513	'
Parent Issuer	'	'	'
Assets:	'	'	'
Current assets	165,929	154,986	'
Property and equipment, net	2,275,639	2,127,624	'
Intercompany receivable (payable)	52,927	59,076	'
Investment in subsidiaries	16,315	12,063	'
Noncurrent assets	17,375	21,770	'
Total	2,528,185	2,375,519	'
Liabilities and Stockholders' Equity:	'	'	'
Current liabilities	236,722	192,106	'
Long-term debt	1,111,703	979,082	'
Deferred income taxes	151,463	158,071	'
Other noncurrent liabilities	57,702	40,542	'
Stockholders' equity	970,595	1,005,718	'
Total liabilities and stockholders' equity	2,528,185	2,375,519	'
Guarantor Subsidiaries	'	'	'
Assets:	'	'	'
Current assets	52	2,261	'
Property and equipment, net	75,317	74,872	'
Intercompany receivable (payable)	-52,927	-59,076	'
Investment in subsidiaries	0	0	'
Noncurrent assets	0	0	'
Total	22,442	18,057	'
Liabilities and Stockholders' Equity:	'	'	'
Current liabilities	1,247	613	'
Long-term debt	0	0	'
Deferred income taxes	3,255	3,255	'
Other noncurrent liabilities	1,625	2,126	'
Stockholders' equity	16,315	12,063	'
Total liabilities and stockholders' equity	22,442	18,057	'
Intercompany Eliminations	'	'	'
Assets:	'	'	'
Current assets	0	0	'
Property and equipment, net	0	0	'
Intercompany receivable (payable)	0	0	'
Investment in subsidiaries	-16,315	-12,063	'
Noncurrent assets	0	0	'
Total	-16,315	-12,063	'
Liabilities and Stockholders' Equity:	'	'	'
Current liabilities	0	0	'
Long-term debt	0	0	'
Deferred income taxes	0	0	'
Other noncurrent liabilities	0	0	'
Stockholders' equity	-16,315	-12,063	'
Total liabilities and stockholders' equity	($16,315)	($12,063)	'

Guarantor_Subsidiaries_Schedul1

Guarantor Subsidiaries - Schedule of Condensed Consolidating Statements of Operations (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]	'	'	'	'	'
Operating and other revenues	$145,008	$142,299	$272,696	$280,576	'
Operating expenses	-104,073	-118,295	-197,137	-234,214	'
General and administrative	-14,521	-13,273	-29,928	-33,855	'
Interest and other income (expense)	-64,244	12,145	-106,455	-42,209	'
Income (loss) before income taxes and equity in earnings (loss) of subsidiaries	-37,830	22,876	-60,824	-29,702	'
(Provision for) Benefit from Income Taxes	11,244	-8,603	21,489	10,824	'
Equity in earnings (loss) of subsidiaries	0	0	0	0	'
Net Income (Loss)	-26,586	14,273	-39,335	-18,878	-192,733
Parent Issuer	'	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'	'
Operating and other revenues	138,355	142,298	260,038	280,576	'
Operating expenses	-99,809	-118,295	-188,696	-234,214	'
General and administrative	-14,521	-13,273	-29,928	-33,855	'
Interest and other income (expense)	-64,279	12,145	-106,490	-42,209	'
Income (loss) before income taxes and equity in earnings (loss) of subsidiaries	-40,254	22,875	-65,076	-29,702	'
(Provision for) Benefit from Income Taxes	11,244	-8,603	21,489	10,824	'
Equity in earnings (loss) of subsidiaries	2,424	1	4,252	0	'
Net Income (Loss)	-26,586	14,273	-39,335	-18,878	'
Guarantor Subsidiaries	'	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'	'
Operating and other revenues	6,653	1	12,658	0	'
Operating expenses	-4,264	0	-8,441	0	'
General and administrative	0	0	0	0	'
Interest and other income (expense)	35	0	35	0	'
Income (loss) before income taxes and equity in earnings (loss) of subsidiaries	2,424	1	4,252	0	'
(Provision for) Benefit from Income Taxes	0	0	0	0	'
Equity in earnings (loss) of subsidiaries	0	0	0	0	'
Net Income (Loss)	2,424	1	4,252	0	'
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	-2,424	-1	-4,252	0	'
Net Income (Loss)	($2,424)	($1)	($4,252)	$0	'

Guarantor_Subsidiaries_Schedul2

Guarantor Subsidiaries - Schedule of Condensed Consolidating Statements of Comprehensive Income (Loss) (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]	'	'	'	'	'
Net income (loss)	($26,586)	$14,273	($39,335)	($18,878)	($192,733)
Effect of derivative financial instruments	-239	-1,210	-336	-2,502	-4,663
Other comprehensive income (loss)	-239	-1,210	-336	-2,502	'
Comprehensive Income (Loss)	-26,825	13,063	-39,671	-21,380	'
Parent Issuer	'	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'	'
Net income (loss)	-26,586	14,273	-39,335	-18,878	'
Effect of derivative financial instruments	-239	-1,210	-336	-2,502	'
Other comprehensive income (loss)	-239	-1,210	-336	-2,502	'
Comprehensive Income (Loss)	-26,825	13,063	-39,671	-21,380	'
Guarantor Subsidiaries	'	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'	'
Net income (loss)	2,424	1	4,252	0	'
Effect of derivative financial instruments	0	0	0	0	'
Other comprehensive income (loss)	0	0	0	0	'
Comprehensive Income (Loss)	2,424	1	4,252	0	'
Intercompany Eliminations	'	'	'	'	'
Condensed Financial Statements, Captions [Line Items]	'	'	'	'	'
Net income (loss)	-2,424	-1	-4,252	0	'
Effect of derivative financial instruments	0	0	0	0	'
Other comprehensive income (loss)	0	0	0	0	'
Comprehensive Income (Loss)	($2,424)	($1)	($4,252)	$0	'

Guarantor_Subsidiaries_Schedul3

Guarantor Subsidiaries - Schedule of Condensed Consolidating Statements of Cash Flows (Detail) (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Condensed Financial Statements, Captions [Line Items]	'	'
Cash flows from operating activities	$127,418	$123,029
Cash flows from investing activities:	'	'
Additions to oil and gas properties, including acquisitions	-264,345	-216,652
Additions to furniture, fixtures and other	-856	-1,187
Proceeds from sale of properties and other investing activities	8,175	4,086
Intercompany Transfers Investing Activities	0	'
Cash flows from financing activities:	'	'
Proceeds from debt	135,000	80,000
Principal payments on debt	-2,285	-4,501
Intercompany Transfer Financing Activities	0	0
Other financing activities	-1,923	-1,345
Increase (Decrease) in Cash and Cash Equivalents	1,184	-16,570
Beginning Cash and Cash Equivalents	54,595	79,445
Ending Cash and Cash Equivalents	55,779	62,875
Parent Issuer	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Cash flows from operating activities	115,705	117,209
Cash flows from investing activities:	'	'
Additions to oil and gas properties, including acquisitions	-257,471	-204,020
Additions to furniture, fixtures and other	-856	731
Proceeds from sale of properties and other investing activities	7,640	4,086
Intercompany Transfers Investing Activities	5,374	'
Cash flows from financing activities:	'	'
Proceeds from debt	135,000	80,000
Principal payments on debt	-2,285	-4,501
Intercompany Transfer Financing Activities	0	-5,546
Other financing activities	-1,923	-1,345
Increase (Decrease) in Cash and Cash Equivalents	1,184	-13,386
Beginning Cash and Cash Equivalents	54,545	79,395
Ending Cash and Cash Equivalents	55,729	66,009
Guarantor Subsidiaries	'	'
Condensed Financial Statements, Captions [Line Items]	'	'
Cash flows from operating activities	11,713	5,820
Cash flows from investing activities:	'	'
Additions to oil and gas properties, including acquisitions	-6,874	-12,632
Additions to furniture, fixtures and other	0	-1,918
Proceeds from sale of properties and other investing activities	535	0
Intercompany Transfers Investing Activities	0	'
Cash flows from financing activities:	'	'
Proceeds from debt	0	0
Principal payments on debt	0	0
Intercompany Transfer Financing Activities	-5,374	5,546
Other financing activities	0	0
Increase (Decrease) in Cash and Cash Equivalents	0	-3,184
Beginning Cash and Cash Equivalents	50	50
Ending Cash and Cash Equivalents	50	-3,134
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
Intercompany Transfers Investing Activities	-5,374	'
Cash flows from financing activities:	'	'
Proceeds from debt	0	0
Principal payments on debt	0	0
Intercompany Transfer Financing Activities	5,374	0
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