Rosetta Resources 10-Q 6 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 29, 2013
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Trading Symbol	'ROSE	'
Entity Registrant Name	'ROSETTA RESOURCES INC.	'
Entity Central Index Key	'0001340282	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	61,267,604

Consolidated_Balance_Sheet

Consolidated Balance Sheet (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$63,956	$36,786
Accounts receivable, net	115,057	103,828
Derivative instruments	10,941	14,437
Prepaid expenses	7,525	5,742
Deferred income taxes	6,546	311
Other current assets	1,285	1,456
Total current assets	205,310	162,560
Oil and natural gas properties using the full cost method of accounting:	'	'
Proved properties	3,629,438	2,829,431
Unproved/unevaluated properties, not subject to amortization	803,493	95,540
Gathering systems and compressor stations	149,471	104,978
Other fixed assets	21,769	16,346
Total property and equipment, gross	4,604,171	3,046,295
Accumulated depreciation, depletion and amortization, including impairment	-1,955,838	-1,808,190
Total property and equipment, net	2,648,333	1,238,105
Other assets:	'	'
Deferred loan fees	16,998	7,699
Derivative instruments	8,245	6,790
Other long-term assets	367	262
Total other assets	25,610	14,751
Total assets	2,879,253	1,415,416
Current liabilities:	'	'
Accounts payable	3,718	1,874
Accrued liabilities	188,093	120,336
Royalties and other payables	80,838	61,637
Derivative instruments	1,534	'
Total current liabilities	274,183	183,847
Long-term liabilities:	'	'
Derivative instruments	'	563
Long-term debt	1,175,000	410,000
Deferred income taxes	99,333	10,086
Other long-term liabilities	15,127	6,921
Total liabilities	1,563,643	611,417
Commitments and Contingencies (Note 9)	'	'
Stockholders' equity:	'	'
Preferred stock, $0.001 par value; authorized 5,000,000 shares; no shares issued in 2013 or 2012	'	'
Common stock, $0.001 par value; authorized 150,000,000 shares; issued 61,985,618 shares and 53,145,853 shares at September 30, 2013 and December 31, 2012, respectively	61	53
Additional paid-in capital	1,179,125	830,539
Treasury stock, at cost; 719,550 and 581,717 shares at September 30, 2013 and December 31, 2012, respectively	-24,317	-17,479
Accumulated other comprehensive income (loss)	-65	-63
Retained earnings (Accumulated deficit)	160,806	-9,051
Total stockholders' equity	1,315,610	803,999
Total liabilities and stockholders' equity	$2,879,253	$1,415,416

Consolidated_Balance_Sheet_Par

Consolidated Balance Sheet (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Statement Of Financial Position [Abstract]	'	'
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	61,985,618	53,145,853
Treasury stock, shares	719,550	581,717

Consolidated_Statement_of_Oper

Consolidated Statement of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:	'	'	'	'
Oil sales	$140,172	$92,377	$353,119	$221,574
NGL sales	50,857	35,179	144,236	114,867
Natural gas sales	34,136	23,019	108,369	62,815
Derivative instruments	-30,597	-27,823	3,484	35,935
Total revenues	194,568	122,752	609,208	435,191
Operating costs and expenses:	'	'	'	'
Lease operating expense	18,963	10,697	44,826	29,434
Treating and transportation	18,807	12,807	52,414	37,330
Production taxes	4,787	5,402	15,442	11,551
Depreciation, depletion and amortization	60,915	40,432	153,382	107,328
General and administrative costs	18,790	19,972	52,830	48,454
Total operating costs and expenses	122,262	89,310	318,894	234,097
Operating income	72,306	33,442	290,314	201,094
Other expense (income):	'	'	'	'
Interest expense, net of interest capitalized	6,907	6,346	26,009	18,316
Interest income	'	-2	'	-6
Other expense (income), net	620	-330	1,061	-331
Total other expense	7,527	6,014	27,070	17,979
Income before provision for income taxes	64,779	27,428	263,244	183,115
Income tax expense	23,754	9,739	93,387	66,160
Net income	$41,025	$17,689	$169,857	$116,955
Earnings per share:	'	'	'	'
Basic	$0.67	$0.34	$2.95	$2.23
Diluted	$0.67	$0.33	$2.93	$2.21
Weighted average shares outstanding:	'	'	'	'
Basic	61,152	52,534	57,656	52,478
Diluted	61,364	52,883	57,924	52,863

Consolidated_Statement_of_Comp

Consolidated Statement of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]	'	'	'	'
Net income	$41,025	$17,689	$169,857	$116,955
Other comprehensive income (loss):	'	'	'	'
Amortization of accumulated other comprehensive gain (loss) related to de-designated hedges, net of income taxes of $58 and $351 for the three months ended September 30, 2013 and 2012, respectively, and $(97) and $784 for the nine months ended September 30, 2013 and 2012, respectively	-102	-616	171	-1,372
Postretirement medical benefits prior service benefit (cost), net of income taxes of $(3) and $98 for the three and nine months ended September 30, 2013, respectively	6	'	-173	'
Other comprehensive income (loss)	-96	-616	-2	-1,372
Comprehensive income	$40,929	$17,073	$169,855	$115,583

Consolidated_Statement_of_Comp1

Consolidated Statement of Comprehensive Income (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]	'	'	'	'
Amortization of accumulated other comprehensive gain (loss) related to de-designated hedges, net of income taxes	$58	$351	($97)	$784
Postretirement medical benefits prior service cost, net of income taxes	($3)	($3)	$98	$98

Consolidated_Statement_of_Cash

Consolidated Statement of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:	'	'
Net income	$169,857	$116,955
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Depreciation, depletion and amortization	153,382	107,328
Deferred income taxes	89,358	66,160
Amortization of deferred loan fees recorded as interest expense	7,674	2,310
Stock-based compensation expense	8,293	12,036
Loss (gain) due to change in fair value of derivative instruments	3,280	-19,069
Change in operating assets and liabilities:	'	'
Accounts receivable	-11,230	-10,069
Prepaid expenses	-652	-223
Other current assets	171	278
Long-term assets	-105	650
Accounts payable	1,844	-1,377
Accrued liabilities	30,503	-18,665
Royalties and other payables	19,201	5,062
Other long-term liabilities	4,189	-2,086
Excess tax benefit from share-based awards	-6,342	'
Net cash provided by operating activities	469,423	259,290
Cash flows from investing activities:	'	'
Acquisitions of oil and gas assets	-952,703	'
Additions to oil and gas assets	-568,140	-458,523
Disposals of oil and gas assets	-1,402	88,489
Net cash used in investing activities	-1,522,245	-370,034
Cash flows from financing activities:	'	'
Borrowings on Credit Facility	580,000	210,000
Payments on Credit Facility	-515,000	-70,000
Payments on Restated Term Loan	'	-20,000
Issuance of Senior Notes	700,000	'
Proceeds from issuance of common stock	329,008	'
Deferred loan fees	-18,102	-1,979
Proceeds from stock options exercised	4,582	898
Purchases of treasury stock	-6,838	-6,048
Excess tax benefit from share-based awards	6,342	'
Net cash provided by financing activities	1,079,992	112,871
Net increase in cash	27,170	2,127
Cash and cash equivalents, beginning of period	36,786	47,050
Cash and cash equivalents, end of period	63,956	49,177
Supplemental disclosures:	'	'
Capital expenditures included in accrued liabilities	$126,780	$92,222

Consolidated_Statement_of_Stoc

Consolidated Statement of Stockholders' Equity (USD $)	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Retained Earnings / (Accumulated Deficit) [Member]
In Thousands, except Share data
Balance at Dec. 31, 2012	$803,999	$53	$830,539	($17,479)	($63)	($9,051)
Balance, Treasury Stock, Shares at Dec. 31, 2012	581,717	'	'	581,717	'	'
Balance, Common Stock, Shares at Dec. 31, 2012	'	53,145,853	'	'	'	'
Issuance of common stock	329,008	8	329,000	'	'	'
Issuance of common stock, Shares	'	8,050,000	'	'	'	'
Excess tax benefit from share - based awards	6,342	'	6,342	'	'	'
Stock options exercised	4,582	'	4,582	'	'	'
Stock options exercised, shares	'	352,481	'	'	'	'
Treasury stock - employee tax payment	-6,838	'	'	-6,838	'	'
Treasury Stock, Shares, Acquired	'	'	'	137,833	'	'
Stock - based compensation	8,662	'	8,662	'	'	'
Vesting of restricted stock, value	'	'	'	'	'	'
Vesting of restricted stock, Shares	'	437,284	'	'	'	'
Comprehensive income	169,855	'	'	'	-2	169,857
Balance at Sep. 30, 2013	$1,315,610	$61	$1,179,125	($24,317)	($65)	$160,806
Balance, Treasury Stock, Shares at Sep. 30, 2013	719,550	'	'	719,550	'	'
Balance, Common Stock, Shares at Sep. 30, 2013	'	61,985,618	'	'	'	'

Organization_and_Operations_of

Organization and Operations of the Company	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Organization and Operations of the Company	'
	(1) Organization and Operations of the Company
	Nature of Operations. Rosetta Resources Inc. (together with its consolidated subsidiaries, the “Company”) is an independent exploration and production company engaged in the acquisition and development of onshore energy resources in the United States of America. The Company’s operations are located in the Eagle Ford shale in South Texas and in the Permian Basin in West Texas.
	These interim financial statements have not been audited. However, in the opinion of management, all adjustments, consisting of normal recurring adjustments necessary to fairly state the financial statements, have been included. Results of operations for interim periods are not necessarily indicative of the results of operations that may be expected for the entire year. In addition, these financial statements have been prepared in accordance with the instructions to Form 10-Q and, therefore, do not include all disclosures required for financial statements prepared in conformity with accounting principles generally accepted in the U.S. (“GAAP”). These financial statements and notes should be read in conjunction with the Company’s audited Consolidated Financial Statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2012 (“2012 Annual Report”).

Summary_of_Significant_Account

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	(2) Summary of Significant Accounting Policies
	The Company has provided a discussion of significant accounting policies, estimates and judgments in its 2012 Annual Report. There have been no changes to the Company’s significant accounting policies since December 31, 2012.
	Recent Accounting Developments
	The following recently issued accounting developments have been applied or may impact the Company in future periods.
	Comprehensive Income. In June 2011, the Financial Accounting Standards Board (“FASB”) issued authoritative guidance to increase the prominence of items reported in other comprehensive income. This guidance requires an entity to present components of other comprehensive income either in a single continuous statement or in two separate but consecutive statements of net income and comprehensive income. In February 2013, the FASB further clarified this guidance relating to the presentation of reclassification adjustments stating that an entity is required to present, either on the face of the statement where net income is presented or in the notes, significant amounts reclassified out of accumulated other comprehensive income. The Company adopted the provisions of the initial guidance effective January 1, 2012 and the provisions of the February 2013 amendment effective January 1, 2013. See the Consolidated Statement of Comprehensive Income, Note 4 – Commodity Derivative Contracts and Note 11 – Stock-Based Compensation and Employee Benefits.
	Offsetting Assets and Liabilities. In December 2011, the FASB issued authoritative guidance requiring entities to disclose both gross and net information about instruments and transactions eligible for offset in the statement of financial position and instruments and transactions subject to an agreement similar to a master netting arrangement. The objective of the disclosure is to facilitate comparison between those entities that prepare their financial statements under GAAP and those entities that prepare their financial statements under International Financial Reporting Standards (IFRS). In January 2013, the FASB issued additional guidance clarifying the scope of these disclosures to include bifurcated embedded derivatives, repurchase and reverse repurchase agreements, and securities borrowing and lending transactions that are either offset or subject to an enforceable master netting arrangement or similar agreement. The Company has adopted this guidance effective January 1, 2013. This guidance requires additional disclosures but did not impact the Company’s consolidated financial position, results of operations or cash flows. See Note 5 – Fair Value Measurements.

Property_and_Equipment

Property and Equipment	9 Months Ended
	Sep. 30, 2013
Extractive Industries [Abstract]	'
Property and Equipment	'
	(3) Property and Equipment
	The Company’s total property and equipment consists of the following:
			September 30, 2013			December 31, 2012
			(In thousands)
	Proved properties		$	3,629,438		$	2,829,431
	Unproved/unevaluated properties			803,493			95,540
	Gathering systems and compressor stations			149,471			104,978
	Other fixed assets			21,769			16,346
	Total property and equipment, gross			4,604,171			3,046,295
	Less: Accumulated depreciation, depletion, and amortization, including impairment			(1,955,838	)		(1,808,190	)
	Total property and equipment, net		$	2,648,333		$	1,238,105
	Acquisitions
	Permian Basin Acquisition. On March 14, 2013, the Company entered into a purchase and sale agreement with Comstock Oil & Gas, LP (“Comstock”) to purchase producing and undeveloped oil and natural gas interests in the Permian Basin in Gaines and Reeves Counties, Texas for $768 million, subject to customary closing adjustments, including adjustments based upon title and environmental due diligence (the “Permian Acquisition”). The Company completed the Permian Acquisition on May 14, 2013 (the “Permian Acquisition Date”), with an effective date of January 1, 2013, for total cash consideration of $825.2 million, subject to further customary closing adjustments. The Permian Acquisition was financed with the proceeds from the Company’s issuance of the 5.625% Senior Notes, as described in Note 7 – Long-Term Debt, and the common stock offering described in Note 10 – Equity. In connection with the Permian Acquisition and related financings, the Company incurred total transaction costs of approximately $31.0 million, including (i) $5.6 million of commitment fees and related expenses associated with a bridge credit facility (“Bridge Credit Facility”), which were recorded as Interest expense since the Company did not borrow under the Bridge Credit Facility, (ii) $10.0 million of debt issuance costs paid in connection with the issuance of the 5.625% Senior Notes, which were deferred and are being amortized over the term of these senior notes, (iii) $13.1 million of equity issuance costs and related expenses associated with the common stock offering, which were reflected as a reduction of equity proceeds, and (iv) $2.3 million of consulting, investment, advisory, legal and other acquisition-related fees, which were expensed and are included in General and administrative costs.
	Gates Ranch Acquisition. In the second quarter of 2013, the Company acquired the remaining 10% working interest in certain producing wells in certain leases of its Gates Ranch leasehold located in the Eagle Ford shale (the “Gates Acquisition”) for total cash consideration of approximately $128.1 million. The transaction closed on June 5, 2013 (the “Gates Acquisition Date”) and was financed with borrowings under the Company’s Credit Facility, as described in Note 7 – Long-Term Debt. As of the Gates Acquisition Date, the Company now owns 100% working interest in the entire Gates Ranch leasehold.
	Both of the above transactions were accounted for under the acquisition method of accounting, whereby the purchase price was allocated to the assets acquired and liabilities assumed based on their estimated fair values, with any excess of the purchase price over the estimated fair value of the identifiable net assets acquired recorded as goodwill (or shortfall of purchase price versus net fair value recorded as bargain purchase). Based on the preliminary purchase price allocation for these acquisitions, no goodwill or bargain purchase was recognized. The combined cash consideration paid for these transactions and the assets and liabilities recognized at the acquisition dates are shown in the table below. Such purchase price allocations are preliminary and may be subject to change based upon customary closing adjustments:
			Total Allocation
			(in thousands)
	Cash consideration		$	953,302
	Fair value of assets acquired:
	Other fixed assets		$	600
	Oil and natural gas properties
	Proved properties			290,333
	Unproved/unevaluated properties			663,300
	Total assets acquired		$	954,233
	Fair value of liabilities assumed:
	Asset retirement obligations		$	931
	Net assets acquired		$	953,302
	The fair value measurements of assets acquired and liabilities assumed are based on inputs that are not observable in the market and therefore represent Level 3 inputs. The fair values of oil and natural gas properties and asset retirement obligations were measured using valuation techniques that convert future cash flows to a single discounted amount. Significant inputs to the valuation of oil and natural gas properties included estimates of: (i) reserves; (ii) production rates; (iii) future operating and development costs; (iv) future commodity prices; (v) future cash flows; and (vi) a market-based weighted average cost of capital rate. These inputs required significant judgments and estimates by the Company’s management at the time of the valuation and are the most sensitive and subject to change.
	The results of operations attributable to the Permian Basin assets and the acquired Gates Ranch working interests were included in the Company’s Consolidated Statement of Operations beginning on May 14, 2013 (Permian Acquisition) and June 5, 2013 (Gates Acquisition), respectively. Revenues of $24.5 million and $37.8 million and net income of $16.8 million and $26.7 million from these acquired assets were generated in the three and nine months ended September 30, 2013, respectively, and are included in the Consolidated Statement of Operations for the three and nine months ended September 30, 2013.
	The following unaudited pro forma information shows the pro forma effects of the acquisitions, the issuance of the 5.625% Senior Notes, the issuance of common stock in the equity offering and the use of proceeds from the debt and equity offerings. The unaudited pro forma information assumes the transactions and related financings occurred on January 1, 2012. The pro forma results of operations have been prepared by adjusting the Company’s historical results to include the historical results of the acquired assets based on information provided by the seller, the Company’s knowledge of the acquired properties and the impact of the Company’s preliminary purchase price allocation. The Company believes the assumptions used provide a reasonable basis for representing the pro forma significant effects directly attributable to the acquisitions and associated financings. The pro forma results of operations do not include any cost savings or other synergies that may result from the Permian Acquisition or any estimated costs that have been or will be incurred by the Company to integrate the Permian assets. The pro forma information does not purport to represent what the Company’s results of operations would have been if such transactions had occurred on January 1, 2012:
			Three Months Ended September 30,						Nine Months Ended September 30,
			2013 (1)			2012			2013		2012
			(In thousands, except per share and share data)						(In thousands, except per share and share data)
	Total revenues		$	194,568		$	140,117		$	641,750	$	477,746
	Net income			41,025			17,033			162,755		111,657
	Earnings per share:
	Basic		$	0.67		$	0.28		$	2.67	$	1.84
	Diluted		$	0.67		$	0.28		$	2.66	$	1.83
	Weighted average shares outstanding:
	Basic			61,152			60,584			61,011		60,528
	Diluted			61,364			60,933			61,279		60,913
	-1	No pro forma adjustments were made for the period as the acquisitions and related financings are included in the Company’s historical results.
	Additional Disclosures about Property and Equipment
	The Company capitalizes internal costs directly identified with acquisition, exploration and development activities. The Company capitalized $1.6 million and $1.2 million of internal costs for the three months ended September 30, 2013 and 2012, respectively, and $5.5 million and $4.7 million for the nine months ended September 30, 2013 and 2012, respectively.
	Oil and gas properties include unevaluated property costs of $803.5 million and $95.5 million as of September 30, 2013 and December 31, 2012, respectively, which are not being amortized. These amounts primarily represent acquisition costs of unproved properties and unevaluated exploration projects in which the Company owns a direct interest, including unevaluated leasehold associated with the Permian Acquisition. Such costs are periodically evaluated for impairment, and upon evaluation or impairment are transferred to the Company’s full cost pool and amortized.
	Pursuant to full cost accounting rules, the Company must perform a ceiling test each quarter on its proved oil and natural gas assets within its U.S. cost center. The Company’s ceiling test was calculated using trailing twelve-month, unweighted-average first-day-of-the-month prices for oil and natural gas as of September 30, 2013, which were based on a West Texas Intermediate oil price of $91.69 per Bbl and a Henry Hub natural gas price of $3.60 per MMBtu (adjusted for basis and quality differentials), respectively. Utilizing these prices, the calculated ceiling amount exceeded the net capitalized cost of oil and natural gas properties. As a result, no write-down was recorded as of September 30, 2013. It is possible that a write-down of the Company’s oil and gas properties could occur in future periods in the event that oil and natural gas prices decline or the Company experiences significant downward adjustments to its estimated proved reserves.

Commodity_Derivative_Contracts

Commodity Derivative Contracts	9 Months Ended
	Sep. 30, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]	'
Commodity Derivative Contracts	'
	(4) Commodity Derivative Contracts
	The Company is exposed to various market risks, including volatility in oil, natural gas liquids (“NGL”) and natural gas prices, which are managed through derivative instruments. The level of derivative activity utilized depends on market conditions, operating strategies and available derivative prices. The Company utilizes various types of derivative instruments to manage commodity price risk, including fixed price swaps, basis swaps, New York Mercantile Exchange (“NYMEX”) roll swaps and costless collars. Forward contracts on various commodities are entered into to manage the price risk associated with forecasted sales of the Company’s oil, NGL and natural gas production.
	As of September 30, 2013, the following derivative contracts were outstanding with associated notional volumes and average underlying prices that represent hedged prices of commodities at various market locations:
	Product	Settlement				Derivative Instrument	Notional			Total			Average			Average
		Period					Daily			Notional			Floor/Fixed			Ceiling Prices
							Volume			Volume			Prices per			per Bbl
							(Bbl)			(Bbl)			Bbl
	Crude oil		2013			Costless Collar		7,750			713,000		$	80.16		$	115.71
	Crude oil		2014			Costless Collar		3,000			1,095,000			83.33			109.63
	Crude oil		2013			Swap		3,000			276,000			95.72
	Crude oil		2014			Swap		6,000			2,190,000			93.13
	Crude oil		2015			Swap		7,000			2,555,000			88.17
											6,829,000
	Product	Settlement				Derivative	Notional			Total			Average
		Period				Instrument	Daily			Notional			Fixed Prices
							Volume			Volume			per Bbl
							(Bbl)			(Bbl)
	Crude oil		2013			Basis Swap		1,875			172,500		$	5.8
	Crude oil		2013			NYMEX Roll Swap		1,875			172,500			(0.18	)
											345,000
	Product	Settlement				Derivative	Notional			Total			Average
		Period				Instrument	Daily			Notional			Fixed Prices
							Volume			Volume			per Bbl
							(Bbl)			(Bbl)
	NGL-Ethane		2013			Swap		3,000			276,000		$	14.43
	NGL-Propane		2013			Swap		2,270			208,840			46.34
	NGL-Isobutane		2013			Swap		705			64,860			69.3
	NGL-Normal Butane		2013			Swap		730			67,160			66.86
	NGL-Pentanes Plus		2013			Swap		795			73,140			86.27
	NGL-Ethane		2014			Swap		2,000			730,000			15.28
	NGL-Propane		2014			Swap		1,535			560,275			43.75
	NGL-Isobutane		2014			Swap		480			175,200			66.71
	NGL-Normal Butane		2014			Swap		475			173,375			64.54
	NGL-Pentanes Plus		2014			Swap		510			186,150			83.96
											2,515,000
	Product	Settlement				Derivative Instrument	Notional			Total			Average			Average
		Period					Daily			Notional			Floor/Fixed			Ceiling Prices
							Volume			Volume			Prices per			per MMBtu
							(MMBtu)			(MMBtu)			MMBtu
	Natural gas		2013			Costless Collar		30,000			2,760,000		$	3.5		$	4.93
	Natural gas		2014			Costless Collar		50,000			18,250,000			3.6			4.94
	Natural gas		2015			Costless Collar		50,000			18,250,000			3.6			5.04
	Natural gas		2013			Swap		30,000			2,760,000			4.11			—
	Natural gas		2014			Swap		30,000			10,950,000			4.07			—
	Natural gas		2015			Swap		40,000			14,600,000			4.18			—
											67,570,000
	As of September 30, 2013, the Company’s derivative instruments were with counterparties who are lenders under the Company’s senior secured revolving credit facility (the “Credit Facility”). This practice allows the Company to satisfy any need for any margin obligations resulting from an adverse change in the fair market value of its derivative contracts with the collateral securing its Credit Facility, thus eliminating the need for independent collateral postings. The Company’s ability to continue satisfying any applicable margin requirements in this manner may be subject to change as described in Items 1 and 2. Business and Properties – Government Regulation in the Company’s 2012 Annual Report. As of September 30, 2013, the Company had no deposits for collateral relating to its commodity derivative instruments.
	Discontinuance of Hedge Accounting
	Effective January 1, 2012, the Company elected to de-designate all commodity contracts previously designated as cash flow hedges as of December 31, 2011, and elected to discontinue hedge accounting prospectively. Accumulated other comprehensive income included $2.6 million ($1.6 million after tax) of unrealized net gains, representing the mark-to-market value of the Company’s cash flow hedges as of December 31, 2011. As a result of discontinuing hedge accounting, the mark-to-market values included in Accumulated other comprehensive income as of the de-designation date were frozen and are being reclassified into earnings as the underlying hedged transactions affect earnings. During the three and nine months ended September 30, 2013, the Company reclassified a $0.2 million ($0.1 million after tax) unrealized net gain and a $0.3 million ($0.2 million after tax) unrealized net loss, respectively, into earnings from Accumulated other comprehensive income. The Company expects to reclassify an additional $0.2 million ($0.1 million after tax) of unrealized net gains into earnings from Accumulated other comprehensive income during the last three months of 2013.
	With the election to de-designate hedging instruments, all of the Company’s derivative instruments continue to be recorded at fair value with unrealized gains and losses recognized immediately in earnings rather than in Accumulated other comprehensive income. These mark-to-market adjustments produce a degree of earnings volatility that can be significant from period to period, but such adjustments had no cash flow impact in the current period. The cash flow impact occurs upon settlement of the underlying contract.
	Additional Disclosures about Derivative Instruments
	Authoritative guidance for derivatives requires companies to recognize all derivative instruments as either assets or liabilities at fair value in the Company’s financial statements. The following table sets forth information on the location and amounts of the Company’s derivative instrument fair values in the Consolidated Balance Sheet as of September 30, 2013 and December 31, 2012, respectively:
				Asset (Liability) Fair Value
				September 30, 2013			December 31, 2012
	Commodity derivative contracts	Location on Consolidated Balance Sheet		(In thousands)
	Oil	Derivative instruments - current assets		$	(872	)	$	564
	Oil	Derivative instruments - non-current assets			238			3,329
	Oil	Derivative instruments - current liabilities			(5,424	)		—
	NGL	Derivative instruments - current assets			6,675			8,361
	NGL	Derivative instruments - non-current assets			2,128			3,534
	NGL	Derivative instruments - current liabilities			1,863			—
	NGL	Derivative instruments - non-current liabilities			—			(563	)
	Natural gas	Derivative instruments - current assets			5,138			5,512
Natural gas	Derivative instruments - non-current assets			5,879			(73	)
Natural gas	Derivative instruments - current liabilities			2,027			—
Total derivative fair value not designated as hedging instruments			$	17,652		$	20,664
The following table sets forth information on the location and amounts of derivative gains and losses in the Consolidated Statement of Operations for the three and nine months ended September 30, 2013 and 2012, respectively:
			Three Months Ended September 30,						Nine Months Ended September 30,
Location on Consolidated			2013			2012			2013			2012
Statement of Operations	Description of Gain (Loss)		(In thousands)
Derivative instruments	Gain recognized in income			1,473			7,624			6,764			16,866
	Realized gain recognized in income		$	1,473		$	7,624		$	6,764		$	16,866
Derivative instruments	(Loss) gain recognized in income due to changes in fair value		$	(32,229	)	$	(36,414	)	$	(3,012	)	$	16,913
Derivative instruments	Gain (loss) reclassified from Accumulated OCI			159			967			(268	)		2,156
	Unrealized (loss) gain recognized in income		$	(32,070	)	$	(35,447	)	$	(3,280	)	$	19,069
	Total commodity derivative (loss) gain recognized in income		$	(30,597	)	$	(27,823	)	$	3,484		$	35,935

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	(5) Fair Value Measurements
	The Company’s financial assets and liabilities are measured at fair value on a recurring basis. The Company measures its non-financial assets and liabilities, such as asset retirement obligations and other property and equipment, at fair value on a non-recurring basis.
	As defined in the FASB’s guidance, fair value is the amount 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 (an exit price). To estimate fair value, the Company utilizes market data and assumptions that market participants would use in pricing the asset or liability, including assumptions about risk and the risks inherent in the inputs to the valuation technique. These inputs can be readily observable, market corroborated or generally unobservable.
	The FASB’s guidance establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted market prices in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). The three levels of the fair value hierarchy are as follows:
		•		“Level 1” inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities.
		•		“Level 2” inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument.
		•		“Level 3” inputs are measured based on prices or valuation models that require inputs that are both significant to the fair value measurement and less observable from objective sources.
	As required, financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of fair value assets and liabilities along with their placement within the fair value hierarchy levels. The Company determines the appropriate level for each financial asset and liability on a quarterly basis and recognizes any transfers at the end of the reporting period.
	The following table sets forth by level within the fair value hierarchy the Company’s financial assets and liabilities that were accounted for at fair value on a recurring basis for the respective period:
			Fair value as of September 30, 2013
			Level 1			Level 2			Level 3			Netting (1)			Total
			(In thousands)
	Assets:
	Money market funds		$	—		$	1,035		$	—		$	—		$	1,035
	Commodity derivative contracts			—			—			25,162			(5,976	)		19,186
	Liabilities:
	Commodity derivative contracts			—			—			(7,510	)		5,976			(1,534	)
	Total fair value		$	—		$	1,035		$	17,652		$	—		$	18,687
			Fair value as of December 31, 2012
			Level 1			Level 2			Level 3			Netting (1)			Total
			(In thousands)
	Assets:
	Money market funds		$	—		$	1,035		$	—		$	—		$	1,035
	Commodity derivative contracts			—			—			27,554			(6,327	)		21,227
	Liabilities:
	Commodity derivative contracts			—			—			(6,890	)		6,327			(563	)
	Total fair value		$	—		$	1,035		$	20,664		$	—		$	21,699
	-1	Represents the impact of netting commodity derivative assets and liabilities with counterparties where the Company has the contractual right and intends to net settle. No margin or collateral balances are deposited with counterparties and as such, gross amounts are offset to determine the net amounts presented in the Consolidated Balance Sheet.
	The Company’s Level 3 instruments include commodity derivative contracts for which fair value is determined by a third-party provider. Although the Company compares the fair values derived from the third-party provider with its counterparties, the Company does not currently have sufficient corroborating market evidence to support classifying these contracts as Level 2 instruments and does not have access to the specific valuation models or certain inputs used by its third-party provider or counterparties. Therefore, these commodity derivative contracts are classified as Level 3 instruments.
	The following table presents a range of the unobservable inputs provided by our third-party provider utilized in the fair value measurements of the Company’s assets and liabilities classified as Level 3 instruments as of September 30, 2013 (in thousands):
									Range						Weighted
	Level 3 Instrument		Asset (Liability)			Valuation Technique		Unobservable Input	Minimum			Maximum			Average
	Oil NYMEX roll swap		$	(201	)	Discounted cash flow		Forward price curve-NYMEX roll swap	$	0.48		$	2.05		$	0.99
	Oil basis swap			515		Discounted cash flow		Forward price curve-basis swap		2.2			3.39			2.81
	Oil swaps			(7,247	)	Discounted cash flow		Forward price curve-swaps		86.51			102.2			92.19
	Oil costless collars			876		Option model		Forward price curve- costless collar option values		(2.42	)		4.65			0.48
	NGL swaps			10,727		Discounted cash flow		Forward price curve-swaps		0.25			2.07			0.84
	NGL swaps			(62	)	Discounted cash flow		Forward price curve-swaps		2.07			2.07			2.07
	Natural gas swaps			7,373		Discounted cash flow		Forward price curve-swaps		3.42			4.26			3.87
	Natural gas costless collars			5,671		Option model		Forward price curve- costless collar option values		(0.26	)		0.37			0.14
	Total derivative fair value		$	17,652
	The determination of derivative fair values by the third-party provider incorporates a credit adjustment for nonperformance risk, including the credit standing of the counterparties involved, and the impact of the Company’s nonperformance risk on its liabilities. The Company recorded a downward adjustment to the fair value of its derivative instruments in the amount of $0.1 million as of September 30, 2013.
	The significant unobservable inputs for Level 3 derivative contracts include forward price curves and option values. Significant increases (decreases) in the quoted forward prices for commodities and option values generally lead to corresponding decreases (increases) in the fair value measurement of the Company’s oil, NGL and natural gas derivative contracts.
	The tables below present reconciliations of financial assets and liabilities classified as Level 3 in the fair value hierarchy during the indicated periods.
			Derivative			Money Market Funds			Total
			Asset (Liability)			Asset (Liability)
			(In thousands)
	Balance at January 1, 2013		$	20,664		$	—		$	20,664
	Total Gains or (Losses) (Realized or Unrealized):
	Included in Earnings			3,752			—			3,752
	Purchases, Issuances and Settlements:
	Settlements			(6,764	)		—			(6,764	)
	Transfers in and out of Level 3			—			—			—
	Balance at September 30, 2013		$	17,652		$	—		$	17,652
			Derivative			Money Market Funds			Total
			Asset (Liability)			Asset (Liability)
			(In thousands)
	Balance at January 1, 2012		$	3,665		$	1,035		$	4,700
	Total Gains or (Losses) (Realized or Unrealized):
	Included in Earnings			33,779			—			33,779
	Included in Other Comprehensive Income			—			—			—
	Purchases, Issuances and Settlements:
	Settlements			(16,866	)		—			(16,866	)
Purchases			—			—			—
Transfers out of Level 3 (1)			—			(1,035	)		(1,035	)
Balance at September 30, 2012		$	20,578		$	—		$	20,578
-1	The value related to the money market funds was transferred from Level 3 to Level 2 during the first quarter of 2012 as a result of the Company’s ability to obtain independent market-corroborated data.
Fair Value of Other Financial Instruments
All of the Company’s other financial instruments (excluding derivatives) are presented on the balance sheet at carrying value. As of September 30, 2013, the carrying values of cash and cash equivalents (excluding money market funds), other current assets and current liabilities reported in the Consolidated Balance Sheet approximate fair value because of their short-term nature, and all such financial instruments are considered Level 1 instruments.
The Company’s debt consists of $200 million in aggregate principal amount of 9.500% Senior Notes due 2018 (the “9.500% Senior Notes”), $700 million in aggregate principal amount of 5.625% Senior Notes due 2021 (the “5.625% Senior Notes”) and borrowings under the Credit Facility. The fair values of the Company’s 9.500% Senior Notes and 5.625% Senior Notes are based upon unadjusted quoted market prices and are considered Level 1 instruments. The Company’s borrowings under the Credit Facility approximate fair value as the interest rates are variable and reflective of current market rates, and are therefore considered a Level 1 instrument. As of September 30, 2013, the carrying amount of total debt was $1.175 billion and the estimated fair value of total debt was $1.155 billion.

Asset_Retirement_Obligations

Asset Retirement Obligations	9 Months Ended
	Sep. 30, 2013
Asset Retirement Obligation Disclosure [Abstract]	'
Asset Retirement Obligations	'
	(6) Asset Retirement Obligations
	The following table provides a rollforward of the Company’s asset retirement obligations (“ARO”). Liabilities incurred during the period include additions to obligations and obligations incurred from acquisitions. Liabilities settled during the period include settlement payments for obligations. Activity related to the Company’s ARO is as follows:
		Nine Months Ended
		September 30, 2013
		(In thousands)
	ARO as of December 31, 2012	$	8,400
	Liabilities incurred during period		1,033
	Liabilities settled during period		(1,354	)
	Accretion expense		430
	ARO as of September 30, 2013	$	8,509
	As of September 30, 2013, the $1.8 million current portion of the total ARO is included in Accrued liabilities, and the $6.7 million long-term portion of ARO is included in Other long-term liabilities on the Consolidated Balance Sheet.

LongTerm_Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Long-Term Debt	'
	(7) Long-Term Debt
	Senior Secured Revolving Credit Facility. On April 12, 2013, the Company entered into the Sixth Amendment to the Amended and Restated Senior Revolving Credit Agreement (the “Amendment”) with Wells Fargo Bank, National Association, as administrative agent, and the lenders signatory thereto. The Amendment, among other things, (i) increased the borrowing base to $800.0 million; (ii) increased the maximum credit amount under the Credit Facility to $1.5 billion; (iii) extended the maturity date to April 12, 2018; and (iv) provided for restrictions on the Company’s ability to pay dividends to its equity holders to be eased upon the Company acquiring investment grade unsecured debt ratings from Moody’s and Standard & Poor’s.
	On July 30, 2013, the Company entered into the Seventh Amendment to the Amended and Restated Senior Revolving Credit Agreement (the “Amendment”) with Wells Fargo Bank, National Association, as administrative agent, and the lenders signatory thereto. The Amendment primarily revises and clarifies language in connection with the hedging restrictions in the Credit Agreement, insofar as it relates to the Company’s ability to maintain incremental hedges added during a pre-acquisition period after such acquisition is successfully consummated.
	At September 30, 2013, the Company’s borrowing base and commitments under the Credit Facility were $800.0 million. Availability under the Credit Facility is restricted to a borrowing base and committed amount, which are subject to review and adjustment on a semi-annual basis and other interim adjustments, including adjustments based on the Company’s hedging arrangements as well as asset divestitures. The amount of the borrowing base and committed amount is affected by a number of factors, including the Company’s level of reserves, as well as the pricing outlook at the time of the redetermination. Therefore, a significant reduction in capital spending could result in a reduced level of reserves that could lower the borrowing base and committed amount.
	As of September 30, 2013, the Company had $275.0 million outstanding with $525.0 million of available borrowing capacity under its Credit Facility. Amounts outstanding under the Credit Facility bear interest at specified margins over the London Interbank Offered Rate (LIBOR) of 1.50% to 2.50%. Additionally, the Company can borrow under the Credit Facility at the Alternative Base Rate (ABR) which is typically based upon the Prime Rate in effect on such day plus a margin of 0.5% to 1.5% depending on the Company’s utilization percentage. The weighted average borrowing rate for the nine months ended September 30, 2013 under the Credit Facility was 3.28%, inclusive of interest and commitment fees. Borrowings under the Credit Facility are collateralized by liens and security interests on substantially all of the Company’s assets, including a mortgage lien on oil and natural gas properties having at least 80% of the pre-tax SEC PV-10 proved reserve value, a guaranty by all of the Company’s domestic subsidiaries and a pledge of 100% of the membership and limited partnership interests of the Company’s domestic subsidiaries. Collateralized amounts under the mortgages are subject to semi-annual reviews based on updated reserve information. The Company is also subject to certain financial covenants including the requirement to maintain a minimum current ratio of consolidated current assets, including the unused amount of available borrowing capacity, to consolidated current liabilities, excluding certain non-cash obligations, of not less than 1.0 to 1.0 as of the end of each fiscal quarter. The terms of the credit agreement also require the maintenance of a maximum leverage ratio of total debt to earnings before interest expense, income taxes and noncash items, such as depreciation, depletion, amortization and impairment, of not greater than 4.0 to 1.0, calculated at the end of each fiscal quarter for the four fiscal quarters then ended, measured quarterly after giving pro forma effect to acquisitions and divestitures. As of September 30, 2013, the Company’s current ratio was 2.7 and leverage ratio was 2.0. In addition, the Company is subject to covenants limiting dividends and other restricted payments, transactions with affiliates, incurrence of debt, changes of control, asset sales and liens on properties.
	9.500% Senior Notes. On April 15, 2010, the Company issued and sold $200.0 million in aggregate principal amount of 9.500% Senior Notes due 2018 in a private offering. Interest is payable on the 9.500% Senior Notes semi-annually on April 15 and October 15. The 9.500% Senior Notes were issued under an indenture (the “9.500% Senior Notes Indenture”) with Wells Fargo Bank, National Association, as trustee. Under the indenture, the Company has the option to redeem the notes on or after April 15, 2014 at a price of $104.75. Provisions of the 9.500% Senior Notes Indenture limit the Company’s ability to, among other things, incur additional indebtedness; pay dividends on capital stock or purchase, repurchase, redeem, defease or retire capital stock or subordinated indebtedness; make investments; incur liens; create any consensual restriction on the ability of the Company’s restricted subsidiaries to pay dividends, make loans or transfer property to the Company; engage in transactions with affiliates; sell assets; and consolidate, merge or transfer assets. The 9.500% Senior Notes Indenture also contains customary events of default. On September 21, 2010, the Company exchanged all of the privately placed 9.500% Senior Notes for registered 9.500% Senior Notes which contain terms substantially identical to the terms of the privately placed notes.
	5.625% Senior Notes. On May 2, 2013, the Company completed its public offering of $700.0 million in aggregate principal amount of 5.625% Senior Notes due 2021. Interest is payable on the 5.625% Senior Notes semi-annually on May 1 and November 1. The 5.625% Senior Notes were issued under an indenture, as supplemented by a first supplemental indenture (the “5.625% Senior Notes Indenture”) with Wells Fargo Bank, National Association, as trustee, which contains covenants and events of default substantially similar to those in the 9.500% Senior Notes Indenture. Net proceeds from the debt offering were used to fund a portion of the consideration for the Permian Acquisition.
	Total Indebtedness. As of September 30, 2013, the Company had total outstanding borrowings of $1.175 billion. For the nine months ended September 30, 2013, the Company’s weighted average borrowing rate was 5.95%, inclusive of interest and commitment fees.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	(8) Income Taxes
	The Company’s effective tax rate for the three and nine months ended September 30, 2013 was 36.7% and 35.5%, respectively, compared to 35.5% and 36.1%, respectively, for the prior comparable periods in the prior year. The provision for income taxes for the three and nine months ended September 30, 2013 differs from the tax computed at the federal statutory income tax rate primarily due to the impact of state income taxes and the non-deductibility of certain incentive compensation. In addition, during the first quarter of 2013 there was a one-time favorable discrete adjustment of (2.9%) to reflect a change in the amount of deductible executive compensation. Excluding discrete items, the effective tax rate for the nine months ended September 30, 2013 was 36.3%. As of September 30, 2013 and December 31, 2012, the Company had no unrecognized tax benefits. The Company does not anticipate that total unrecognized tax benefits will significantly change due to the settlement of audits or the expiration of statutes of limitation within the next twelve months.
	The Company provides for deferred income taxes on the difference between the tax basis of an asset or liability and its carrying amount in the financial statements in accordance with authoritative guidance for accounting for income taxes. This difference will result in taxable income or deductions in future years when the reported amount of the asset or liability is recovered or settled, respectively. Considerable judgment is required in determining when these events may occur and whether recovery of an asset is more likely than not. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that some portion or all of the deferred tax assets will not be realized. As of September 30, 2013, the Company had a net deferred tax liability of $92.8 million resulting primarily from the differences between the book basis and tax basis of the Company’s oil and natural gas properties, partially offset by net operating loss carryforwards.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	(9) Commitments and Contingencies
	Firm Oil and Natural Gas Transportation and Processing Commitments. The Company has commitments for the transportation and processing of its production in the Eagle Ford area and has an aggregate minimum commitment to deliver 6.5 MMBbls of oil by the end of 2017 and 378 million MMBtus of natural gas by the end of 2023. The Company is required to make periodic deficiency payments for any shortfalls in delivering the minimum volumes under these commitments. Currently, the Company has insufficient production to meet all of these contractual commitments, and as of September 30, 2013, the Company has accrued deficiency fees of $6.5 million. Future obligations under firm oil and natural gas transportation and processing agreements as of September 30, 2013 are as follows:
		September 30, 2013
		(In thousands)
	2013	$	8,692
	2014		34,486
	2015		34,313
	2016		33,844
	2017		33,388
	Thereafter through 2023		133,928
	Total future obligations	$	278,651
	Drilling Rig and Completion Services Commitments. Drilling rig and completion services commitments represent obligations with certain contractors to execute the Company’s Eagle Ford and Permian Basin drilling programs, and payments under these commitments are accounted for as capital additions to oil and gas properties. As of September 30, 2013, the Company had one outstanding drilling rig commitment with a term greater than one year, and minimum contractual commitments due in the next twelve months are $4.6 million. As of September 30, 2013, the Company’s minimum contractual commitments for completion services agreements for the stimulation, cementing and delivery of drilling fluids was $9.5 million.
	Contingencies. The Company is party to various legal and regulatory proceedings and commercial disputes arising in the normal course of business. The Company has evaluated the need for a reserve for each respective matter in accordance with applicable accounting guidance and recorded a $0.5 million reserve related to a commercial dispute, which is included in Other expense (income), net in the Consolidated Statement of Operations for the three and nine months ended September 30, 2013 and Accrued liabilities in the Consolidated Balance Sheet as of September 30, 2013. The outcomes of all remaining matters are not known and the related damages, if any, cannot be reasonably estimated at this time. The Company intends to vigorously defend its position in all such disputes; however, it is remotely possible that an adverse decision or settlement of one or more of such matters could have a material effect on the Company, its financial condition, results of operations and cash flows.

Equity

Equity	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
Equity	'
	(10) Equity
	Earnings per Share. Basic earnings per share (“EPS”) is calculated by dividing net income (the numerator) by the weighted-average number of shares of common stock (excluding unvested restricted stock awards) outstanding during the period (the denominator). Diluted earnings per share incorporates the dilutive impact of outstanding stock options and unvested restricted stock awards using the treasury stock method.
	The following is a calculation of basic and diluted weighted average shares outstanding:
		Three Months Ended September 30,				Nine Months Ended September 30,
		2013		2012		2013		2012
		(In thousands)
	Basic weighted average number of shares outstanding		61,152		52,534		57,656		52,478
	Dilution effect of stock option and restricted shares at the end of the period		212		349		268		385
	Diluted weighted average number of shares outstanding		61,364		52,883		57,924		52,863
	Anti-dilutive stock awards and shares		—		1		—		2
	Common Stock Offering. On April 23, 2013, the Company completed its public offering of 7,000,000 shares of common stock at a price to the public of $42.50 per share ($40.80 per share, net of underwriting discount and structuring fee) for net proceeds of approximately $286.3 million including reimbursement by the underwriters. The Company also received net proceeds of approximately $43.0 million in connection with the underwriters’ full exercise of their over-allotment option to issue an additional 1,050,000 shares of common stock, which closed on April 29, 2013. The Company used net proceeds from the offering to repay outstanding indebtedness under its Credit Facility and to fund a portion of the consideration for the Permian Acquisition.

StockBased_Compensation_and_Em

Stock-Based Compensation and Employee Benefits	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock-Based Compensation and Employee Benefits	'
	(11) Stock-Based Compensation and Employee Benefits
	Stock-based compensation expense includes the expense associated with restricted stock granted to employees and directors and the expense associated with the Performance Share Units (“PSUs”) granted to management. As of the indicated dates, stock-based compensation expense consisted of the following:
		Three Months Ended September 30,					Nine Months Ended September 30,
		2013			2012		2013			2012
		(In thousands)
	Total stock-based compensation	$	3,621		$	6,453	$	8,662		$	12,258
	Capitalized in oil and gas properties		(221	)		101		(369	)		(222	)
	Net stock-based compensation expense	$	3,400		$	6,554	$	8,293		$	12,036
	All stock-based compensation expense associated with restricted stock granted to employees and directors is recognized on a straight-line basis over the applicable remaining vesting period. For the three and nine months ended September 30, 2013, the Company recorded compensation expense of approximately $1.7 million and $4.6 million, respectively, related to these equity awards. As of September 30, 2013, unrecognized stock-based compensation expense related to unvested restricted stock was approximately $10.8 million.
	Stock-based compensation expense associated with the PSUs granted to management is recognized over a three-year performance period. For the three and nine months ended September 30, 2013, the Company recognized compensation expense of $1.9 million and $4.0 million, respectively, associated with the PSUs. At the current fair value as of September 30, 2013 and assuming the Board elects the maximum available payout of 200% for all PSU metrics, unrecognized stock-based compensation expense related to the PSUs was approximately $13.4 million. The Company’s total stock-based compensation expense will be measured and adjusted quarterly until settlement occurs, based on the Company’s performance, expected payout and quarter-end closing common stock prices. For a more detailed description of the Company’s PSU plans, including related performance conditions and structure, see the definitive proxy statement filed with respect to the Company’s 2013 annual meeting under the heading “Compensation Discussion and Analysis” and the Company’s 2012 Annual Report.
	Postretirement Health Care. Effective January 1, 2013, the Company enacted a postretirement medical benefit plan covering eligible employees and their eligible dependents. Upon enactment, the Company recognized a $0.3 million liability related to the prior service of employees which is included as a component of Other comprehensive income, net of the related tax benefit. The Company recognizes periodic postretirement benefits cost as a component of General and administrative costs. For both the three and nine months ended September 30, 2013, this expense was immaterial.

Guarantor_Subsidiaries

Guarantor Subsidiaries	9 Months Ended
	Sep. 30, 2013
Guarantees [Abstract]	'
Guarantor Subsidiaries	'
	(12) Guarantor Subsidiaries
	The Company’s 9.500% Senior Notes and 5.625% Senior Notes are guaranteed by its wholly owned subsidiaries. Rosetta Resources Inc., as the parent company, has no independent assets or operations. The guarantees are full and unconditional and joint and several. In addition, there are no restrictions on the ability of the Company to obtain funds from its subsidiaries by dividend or loan. Finally, none of the Company’s subsidiaries has restricted assets that exceed 25% of net assets as of the most recent fiscal year which may not be transferred to the Company in the form of loans, advances or cash dividends by the subsidiaries without the consent of a third party.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]	'
Recent Accounting Developments	'
	Recent Accounting Developments
	The following recently issued accounting developments have been applied or may impact the Company in future periods.
	Comprehensive Income. In June 2011, the Financial Accounting Standards Board (“FASB”) issued authoritative guidance to increase the prominence of items reported in other comprehensive income. This guidance requires an entity to present components of other comprehensive income either in a single continuous statement or in two separate but consecutive statements of net income and comprehensive income. In February 2013, the FASB further clarified this guidance relating to the presentation of reclassification adjustments stating that an entity is required to present, either on the face of the statement where net income is presented or in the notes, significant amounts reclassified out of accumulated other comprehensive income. The Company adopted the provisions of the initial guidance effective January 1, 2012 and the provisions of the February 2013 amendment effective January 1, 2013. See the Consolidated Statement of Comprehensive Income, Note 4 – Commodity Derivative Contracts and Note 11 – Stock-Based Compensation and Employee Benefits.
	Offsetting Assets and Liabilities. In December 2011, the FASB issued authoritative guidance requiring entities to disclose both gross and net information about instruments and transactions eligible for offset in the statement of financial position and instruments and transactions subject to an agreement similar to a master netting arrangement. The objective of the disclosure is to facilitate comparison between those entities that prepare their financial statements under GAAP and those entities that prepare their financial statements under International Financial Reporting Standards (IFRS). In January 2013, the FASB issued additional guidance clarifying the scope of these disclosures to include bifurcated embedded derivatives, repurchase and reverse repurchase agreements, and securities borrowing and lending transactions that are either offset or subject to an enforceable master netting arrangement or similar agreement. The Company has adopted this guidance effective January 1, 2013. This guidance requires additional disclosures but did not impact the Company’s consolidated financial position, results of operations or cash flows. See Note 5 – Fair Value Measurements.

Property_and_Equipment_Tables

Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2013
Extractive Industries [Abstract]	'
Schedule of Total Property, Plant and Equipment	'
	The Company’s total property and equipment consists of the following:
			September 30, 2013			December 31, 2012
			(In thousands)
	Proved properties		$	3,629,438		$	2,829,431
	Unproved/unevaluated properties			803,493			95,540
	Gathering systems and compressor stations			149,471			104,978
	Other fixed assets			21,769			16,346
	Total property and equipment, gross			4,604,171			3,046,295
	Less: Accumulated depreciation, depletion, and amortization, including impairment			(1,955,838	)		(1,808,190	)
	Total property and equipment, net		$	2,648,333		$	1,238,105
Schedule of Consideration Paid for the Transactions of Asset Acquired and Liabilities Assumed	'
	The combined cash consideration paid for these transactions and the assets and liabilities recognized at the acquisition dates are shown in the table below.
			Total Allocation
			(in thousands)
	Cash consideration		$	953,302
	Fair value of assets acquired:
	Other fixed assets		$	600
	Oil and natural gas properties
	Proved properties			290,333
	Unproved/unevaluated properties			663,300
	Total assets acquired		$	954,233
	Fair value of liabilities assumed:
	Asset retirement obligations		$	931
	Net assets acquired		$	953,302
Schedule of Results of Operations at the Time of Transactions	'
	The pro forma information does not purport to represent what the Company’s results of operations would have been if such transactions had occurred on January 1, 2012:
			Three Months Ended September 30,						Nine Months Ended September 30,
			2013 (1)			2012			2013		2012
			(In thousands, except per share and share data)						(In thousands, except per share and share data)
	Total revenues		$	194,568		$	140,117		$	641,750	$	477,746
	Net income			41,025			17,033			162,755		111,657
	Earnings per share:
	Basic		$	0.67		$	0.28		$	2.67	$	1.84
	Diluted		$	0.67		$	0.28		$	2.66	$	1.83
	Weighted average shares outstanding:
	Basic			61,152			60,584			61,011		60,528
	Diluted			61,364			60,933			61,279		60,913
	-1	No pro forma adjustments were made for the period as the acquisitions and related financings are included in the Company’s historical results.

Commodity_Derivative_Contracts1

Commodity Derivative Contracts (Tables)	9 Months Ended
	Sep. 30, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]	'
Schedule of Derivative Instruments	'
	As of September 30, 2013, the following derivative contracts were outstanding with associated notional volumes and average underlying prices that represent hedged prices of commodities at various market locations:
	Product	Settlement				Derivative Instrument	Notional			Total			Average			Average
		Period					Daily			Notional			Floor/Fixed			Ceiling Prices
							Volume			Volume			Prices per			per Bbl
							(Bbl)			(Bbl)			Bbl
	Crude oil		2013			Costless Collar		7,750			713,000		$	80.16		$	115.71
	Crude oil		2014			Costless Collar		3,000			1,095,000			83.33			109.63
	Crude oil		2013			Swap		3,000			276,000			95.72
	Crude oil		2014			Swap		6,000			2,190,000			93.13
	Crude oil		2015			Swap		7,000			2,555,000			88.17
											6,829,000
	Product	Settlement				Derivative	Notional			Total			Average
		Period				Instrument	Daily			Notional			Fixed Prices
							Volume			Volume			per Bbl
							(Bbl)			(Bbl)
	Crude oil		2013			Basis Swap		1,875			172,500		$	5.8
	Crude oil		2013			NYMEX Roll Swap		1,875			172,500			(0.18	)
											345,000
	Product	Settlement				Derivative	Notional			Total			Average
		Period				Instrument	Daily			Notional			Fixed Prices
							Volume			Volume			per Bbl
							(Bbl)			(Bbl)
	NGL-Ethane		2013			Swap		3,000			276,000		$	14.43
	NGL-Propane		2013			Swap		2,270			208,840			46.34
	NGL-Isobutane		2013			Swap		705			64,860			69.3
	NGL-Normal Butane		2013			Swap		730			67,160			66.86
	NGL-Pentanes Plus		2013			Swap		795			73,140			86.27
	NGL-Ethane		2014			Swap		2,000			730,000			15.28
	NGL-Propane		2014			Swap		1,535			560,275			43.75
	NGL-Isobutane		2014			Swap		480			175,200			66.71
	NGL-Normal Butane		2014			Swap		475			173,375			64.54
	NGL-Pentanes Plus		2014			Swap		510			186,150			83.96
											2,515,000
	Product	Settlement				Derivative Instrument	Notional			Total			Average			Average
		Period					Daily			Notional			Floor/Fixed			Ceiling Prices
							Volume			Volume			Prices per			per MMBtu
							(MMBtu)			(MMBtu)			MMBtu
	Natural gas		2013			Costless Collar		30,000			2,760,000		$	3.5		$	4.93
	Natural gas		2014			Costless Collar		50,000			18,250,000			3.6			4.94
	Natural gas		2015			Costless Collar		50,000			18,250,000			3.6			5.04
	Natural gas		2013			Swap		30,000			2,760,000			4.11			—
	Natural gas		2014			Swap		30,000			10,950,000			4.07			—
	Natural gas		2015			Swap		40,000			14,600,000			4.18			—
											67,570,000
Schedule of Derivative Instruments in Statement of Financial Position	'
	The following table sets forth information on the location and amounts of the Company’s derivative instrument fair values in the Consolidated Balance Sheet as of September 30, 2013 and December 31, 2012, respectively:
				Asset (Liability) Fair Value
				September 30, 2013			December 31, 2012
	Commodity derivative contracts	Location on Consolidated Balance Sheet		(In thousands)
	Oil	Derivative instruments - current assets		$	(872	)	$	564
	Oil	Derivative instruments - non-current assets			238			3,329
	Oil	Derivative instruments - current liabilities			(5,424	)		—
	NGL	Derivative instruments - current assets			6,675			8,361
	NGL	Derivative instruments - non-current assets			2,128			3,534
	NGL	Derivative instruments - current liabilities			1,863			—
	NGL	Derivative instruments - non-current liabilities			—			(563	)
	Natural gas	Derivative instruments - current assets			5,138			5,512
	Natural gas	Derivative instruments - non-current assets			5,879			(73	)
	Natural gas	Derivative instruments - current liabilities			2,027			—
	Total derivative fair value not designated as hedging instruments			$	17,652		$	20,664
Schedule of Derivative Gains and Losses in Consolidated Statement of Operations	'
	The following table sets forth information on the location and amounts of derivative gains and losses in the Consolidated Statement of Operations for the three and nine months ended September 30, 2013 and 2012, respectively:
				Three Months Ended September 30,						Nine Months Ended September 30,
	Location on Consolidated			2013			2012			2013			2012
	Statement of Operations	Description of Gain (Loss)		(In thousands)
	Derivative instruments	Gain recognized in income			1,473			7,624			6,764			16,866
		Realized gain recognized in income		$	1,473		$	7,624		$	6,764		$	16,866
	Derivative instruments	(Loss) gain recognized in income due to changes in fair value		$	(32,229	)	$	(36,414	)	$	(3,012	)	$	16,913
	Derivative instruments	Gain (loss) reclassified from Accumulated OCI			159			967			(268	)		2,156
		Unrealized (loss) gain recognized in income		$	(32,070	)	$	(35,447	)	$	(3,280	)	$	19,069
		Total commodity derivative (loss) gain recognized in income		$	(30,597	)	$	(27,823	)	$	3,484		$	35,935

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis	'
	The following table sets forth by level within the fair value hierarchy the Company’s financial assets and liabilities that were accounted for at fair value on a recurring basis for the respective period:
			Fair value as of September 30, 2013
			Level 1			Level 2			Level 3			Netting (1)			Total
			(In thousands)
	Assets:
	Money market funds		$	—		$	1,035		$	—		$	—		$	1,035
	Commodity derivative contracts			—			—			25,162			(5,976	)		19,186
	Liabilities:
	Commodity derivative contracts			—			—			(7,510	)		5,976			(1,534	)
	Total fair value		$	—		$	1,035		$	17,652		$	—		$	18,687
			Fair value as of December 31, 2012
			Level 1			Level 2			Level 3			Netting (1)			Total
			(In thousands)
	Assets:
	Money market funds		$	—		$	1,035		$	—		$	—		$	1,035
	Commodity derivative contracts			—			—			27,554			(6,327	)		21,227
	Liabilities:
	Commodity derivative contracts			—			—			(6,890	)		6,327			(563	)
	Total fair value		$	—		$	1,035		$	20,664		$	—		$	21,699
	-1	Represents the impact of netting commodity derivative assets and liabilities with counterparties where the Company has the contractual right and intends to net settle. No margin or collateral balances are deposited with counterparties and as such, gross amounts are offset to determine the net amounts presented in the Consolidated Balance Sheet.
Schedule of Valuation Process and Unobservable Inputs	'
	The following table presents a range of the unobservable inputs provided by our third-party provider utilized in the fair value measurements of the Company’s assets and liabilities classified as Level 3 instruments as of September 30, 2013 (in thousands):
									Range						Weighted
	Level 3 Instrument		Asset (Liability)			Valuation Technique		Unobservable Input	Minimum			Maximum			Average
	Oil NYMEX roll swap		$	(201	)	Discounted cash flow		Forward price curve-NYMEX roll swap	$	0.48		$	2.05		$	0.99
	Oil basis swap			515		Discounted cash flow		Forward price curve-basis swap		2.2			3.39			2.81
	Oil swaps			(7,247	)	Discounted cash flow		Forward price curve-swaps		86.51			102.2			92.19
	Oil costless collars			876		Option model		Forward price curve- costless collar option values		(2.42	)		4.65			0.48
	NGL swaps			10,727		Discounted cash flow		Forward price curve-swaps		0.25			2.07			0.84
	NGL swaps			(62	)	Discounted cash flow		Forward price curve-swaps		2.07			2.07			2.07
	Natural gas swaps			7,373		Discounted cash flow		Forward price curve-swaps		3.42			4.26			3.87
	Natural gas costless collars			5,671		Option model		Forward price curve- costless collar option values		(0.26	)		0.37			0.14
	Total derivative fair value		$	17,652
Schedule of Fair Value Assets and Liabilities Classified	'
	The tables below present reconciliations of financial assets and liabilities classified as Level 3 in the fair value hierarchy during the indicated periods.
			Derivative			Money Market Funds			Total
			Asset (Liability)			Asset (Liability)
			(In thousands)
	Balance at January 1, 2013		$	20,664		$	—		$	20,664
	Total Gains or (Losses) (Realized or Unrealized):
	Included in Earnings			3,752			—			3,752
	Purchases, Issuances and Settlements:
	Settlements			(6,764	)		—			(6,764	)
	Transfers in and out of Level 3			—			—			—
	Balance at September 30, 2013		$	17,652		$	—		$	17,652
			Derivative			Money Market Funds			Total
			Asset (Liability)			Asset (Liability)
			(In thousands)
	Balance at January 1, 2012		$	3,665		$	1,035		$	4,700
	Total Gains or (Losses) (Realized or Unrealized):
	Included in Earnings			33,779			—			33,779
	Included in Other Comprehensive Income			—			—			—
	Purchases, Issuances and Settlements:
	Settlements			(16,866	)		—			(16,866	)
	Purchases			—			—			—
	Transfers out of Level 3 (1)			—			(1,035	)		(1,035	)
	Balance at September 30, 2012		$	20,578		$	—		$	20,578
	-1	The value related to the money market funds was transferred from Level 3 to Level 2 during the first quarter of 2012 as a result of the Company’s ability to obtain independent market-corroborated data.

Asset_Retirement_Obligations_T

Asset Retirement Obligations (Tables)	9 Months Ended
	Sep. 30, 2013
Asset Retirement Obligation Disclosure [Abstract]	'
Schedule of Asset Retirement Obligations	'
	Activity related to the Company’s ARO is as follows:
		Nine Months Ended
		September 30, 2013
		(In thousands)
	ARO as of December 31, 2012	$	8,400
	Liabilities incurred during period		1,033
	Liabilities settled during period		(1,354	)
	Accretion expense		430
	ARO as of September 30, 2013	$	8,509

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Future Obligations Under Firm Gas and Oil Transportation Agreements	'
	Future obligations under firm oil and natural gas transportation and processing agreements as of September 30, 2013 are as follows:
		September 30,
		2013
		(In thousands)
	2013	$	8,692
	2014		34,486
	2015		34,313
	2016		33,844
	2017		33,388
	Thereafter through 2023		133,928
	Total future obligations	$	278,651

Equity_Tables

Equity (Tables)	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]	'
Schedule of Basic and Diluted Weighted Average Shares Outstanding	'
	The following is a calculation of basic and diluted weighted average shares outstanding:
		Three Months Ended September 30,				Nine Months Ended September 30,
		2013		2012		2013		2012
		(In thousands)
	Basic weighted average number of shares outstanding		61,152		52,534		57,656		52,478
	Dilution effect of stock option and restricted shares at the end of the period		212		349		268		385
	Diluted weighted average number of shares outstanding		61,364		52,883		57,924		52,863
	Anti-dilutive stock awards and shares		—		1		—		2

StockBased_Compensation_and_Em1

Stock-Based Compensation and Employee Benefits (Tables)	9 Months Ended
	Sep. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Schedule of Stock-Based Compensation Expense	'
	As of the indicated dates, stock-based compensation expense consisted of the following:
		Three Months Ended September 30,					Nine Months Ended September 30,
		2013			2012		2013			2012
		(In thousands)
	Total stock-based compensation	$	3,621		$	6,453	$	8,662		$	12,258
	Capitalized in oil and gas properties		(221	)		101		(369	)		(222	)
	Net stock-based compensation expense	$	3,400		$	6,554	$	8,293		$	12,036

Property_and_Equipment_Schedul

Property and Equipment - Schedule of Total Property, Plant and Equipment (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Capitalized Costs, Oil and Gas Producing Activities, Net [Abstract]	'	'
Proved properties	$3,629,438	$2,829,431
Unproved/unevaluated properties	803,493	95,540
Gathering systems and compressor stations	149,471	104,978
Other fixed assets	21,769	16,346
Total property and equipment, gross	4,604,171	3,046,295
Less: Accumulated depreciation, depletion, and amortization, including impairment	-1,955,838	-1,808,190
Total property and equipment, net	$2,648,333	$1,238,105

Property_and_Equipment_Additio

Property and Equipment - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

1 Months Ended

9 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Mar. 14, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Bridge Loan [Member]

Senior Notes [Member]

Texas [Member]

Texas [Member]

Eagle Ford Shale [Member]

Eagle Ford Shale [Member]

Adjusted For Basis And Quality Differentials [Member]

South Texas Gates Ranch [Member]

Property, Plant and Equipment [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

Consideration of purchase and sale agreement for divestiture

'

'

$952,703,000

'

'

'

'

$768,000,000

'

'

'

'

Acquisition date

'

'

'

'

'

'

'

14-May-13

'

'

'

'

Acquisition effective date

'

'

'

'

'

'

'

1-Jan-13

'

'

'

'

Payments to Acquire Businesses

'

'

'

'

'

'

'

'

825,200,000

'

'

'

Transaction cost

31,000,000

'

31,000,000

'

'

'

'

'

'

'

'

'

Commitment fees and related expenses

'

'

'

'

'

5,600,000

'

'

'

'

'

'

Debt issuance costs

'

'

'

'

'

'

10,000,000

'

'

'

'

'

Equity issuance costs and related expenses

'

'

13,100,000

'

'

'

'

'

'

'

'

'

Acquisition related fees, Included in General and administrative costs

'

'

2,300,000

'

'

'

'

'

'

'

'

'

Working Interest Acquisition Date

'

'

'

'

'

'

'

'

'

5-Jun-13

'

'

Percentage of Working Interests Acquired

'

'

'

'

'

'

'

'

'

10.00%

100.00%

'

Working Interest Acquisition, Total Consideration

'

'

'

'

'

'

'

'

'

128,100,000

'

'

Revenue From Acquired Business Included In Consolidated Statements Of Income

24,500,000

'

37,800,000

'

'

'

'

'

'

'

'

'

Net Income Loss From Acquired Business Included In Consolidated Statements Of Income

16,800,000

'

26,700,000

'

'

'

'

'

'

'

'

'

Anticipated increase in depletion rate

'

'

20.00%

'

'

'

'

'

'

'

'

'

Capitalized internal cost

1,600,000

1,200,000

5,500,000

4,700,000

'

'

'

'

'

'

'

'

Oil and natural gas properties excluded from amortization, full cost method

'

'

$803,500,000

'

$95,500,000

'

'

'

'

'

'

'

West Texas Intermediate oil price (per Bbl)

'

'

'

'

'

'

'

'

'

'

'

91.69

Henry Hub natural gas price (per MMBtu)

'

'

'

'

'

'

'

'

'

'

'

3.6

Property_and_Equipment_Schedul1

Property and Equipment - Schedule of Consideration Paid for the Transactions of Asset Acquired and Liabilities Assumed (Detail) (Level 3 [Member], USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Level 3 [Member]	'
Property Plant And Equipment Disclosure [Line Items]	'
Cash consideration	$953,302
Fair value of assets acquired :	'
Other fixed assets	600
Oil and natural gas properties	'
Proved properties	290,333
Unproved/unevaluated properties	663,300
Total assets acquired	954,233
Fair value of liabilities assumed:	'
Asset retirement obligations	931
Net assets acquired	$953,302

Property_and_Equipment_Schedul2

Property and Equipment - Schedule of Results of Operations at the Time of Transactions (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Property Plant And Equipment Useful Life And Values [Abstract]	'	'	'	'
Total revenues	$194,568	$140,117	$641,750	$477,746
Net income	$41,025	$17,033	$162,755	$111,657
Earnings per share:	'	'	'	'
Basic	$0.67	$0.28	$2.67	$1.84
Diluted	$0.67	$0.28	$2.66	$1.83
Weighted average shares outstanding:	'	'	'	'
Basic	61,152	60,584	61,011	60,528
Diluted	61,364	60,933	61,279	60,913

Commodity_Derivative_Contracts2

Commodity Derivative Contracts - Schedule of Derivative Instruments (Detail)	Sep. 30, 2013
	bbl
Derivative Instruments, Gain (Loss) [Line Items]	'
Total Notional Volume	6,829,000
Natural Gas [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Total Notional Volume MMBtu	67,570,000
NGL-Product [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Total Notional Volume	2,515,000
Costless Collar [Member] | 2013 Settlement Period [Member] | Natural Gas [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume MMBtu	30,000
Total Notional Volume MMBtu	2,760,000
Average Floor/ Prices per	3.5
Average Ceiling Prices per	4.93
Costless Collar [Member] | 2013 Settlement Period [Member] | Crude Oil [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	7,750
Total Notional Volume	713,000
Average Floor/ Prices per	80.16
Average Ceiling Prices per	115.71
Costless Collar [Member] | 2014 Settlement Period [Member] | Natural Gas [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume MMBtu	50,000
Total Notional Volume MMBtu	18,250,000
Average Floor/ Prices per	3.6
Average Ceiling Prices per	4.94
Costless Collar [Member] | 2014 Settlement Period [Member] | Crude Oil [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	3,000
Total Notional Volume	1,095,000
Average Floor/ Prices per	83.33
Average Ceiling Prices per	109.63
Costless Collar [Member] | 2015 Settlement Period [Member] | Natural Gas [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume MMBtu	50,000
Total Notional Volume MMBtu	18,250,000
Average Floor/ Prices per	3.6
Average Ceiling Prices per	5.04
Swap [Member] | 2013 Settlement Period [Member] | Natural Gas [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume MMBtu	30,000
Total Notional Volume MMBtu	2,760,000
Average Floor/ Prices per	4.11
Swap [Member] | 2013 Settlement Period [Member] | NGL-Ethane [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	3,000
Total Notional Volume	276,000
Average Floor/ Prices per	14.43
Swap [Member] | 2013 Settlement Period [Member] | NGL-Propane [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	2,270
Total Notional Volume	208,840
Average Floor/ Prices per	46.34
Swap [Member] | 2013 Settlement Period [Member] | NGL-Isobutane [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	705
Total Notional Volume	64,860
Average Floor/ Prices per	69.3
Swap [Member] | 2013 Settlement Period [Member] | NGL-Normal Butane [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	730
Total Notional Volume	67,160
Average Floor/ Prices per	66.86
Swap [Member] | 2013 Settlement Period [Member] | NGL-Pentanes Plus [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	795
Total Notional Volume	73,140
Average Floor/ Prices per	86.27
Swap [Member] | 2013 Settlement Period [Member] | Crude Oil [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	3,000
Total Notional Volume	276,000
Average Floor/ Prices per	95.72
Swap [Member] | 2014 Settlement Period [Member] | Natural Gas [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume MMBtu	30,000
Total Notional Volume MMBtu	10,950,000
Average Floor/ Prices per	4.07
Swap [Member] | 2014 Settlement Period [Member] | NGL-Ethane [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	2,000
Total Notional Volume	730,000
Average Floor/ Prices per	15.28
Swap [Member] | 2014 Settlement Period [Member] | NGL-Propane [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	1,535
Total Notional Volume	560,275
Average Floor/ Prices per	43.75
Swap [Member] | 2014 Settlement Period [Member] | NGL-Isobutane [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	480
Total Notional Volume	175,200
Average Floor/ Prices per	66.71
Swap [Member] | 2014 Settlement Period [Member] | NGL-Normal Butane [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	475
Total Notional Volume	173,375
Average Floor/ Prices per	64.54
Swap [Member] | 2014 Settlement Period [Member] | NGL-Pentanes Plus [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	510
Total Notional Volume	186,150
Average Floor/ Prices per	83.96
Swap [Member] | 2014 Settlement Period [Member] | Crude Oil [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	6,000
Total Notional Volume	2,190,000
Average Floor/ Prices per	93.13
Swap [Member] | 2015 Settlement Period [Member] | Natural Gas [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume MMBtu	40,000
Total Notional Volume MMBtu	14,600,000
Average Floor/ Prices per	4.18
Swap [Member] | 2015 Settlement Period [Member] | Crude Oil [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	7,000
Total Notional Volume	2,555,000
Average Floor/ Prices per	88.17
Basis Swap [Member] | 2013 Settlement Period [Member] | Crude Oil [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	1,875
Total Notional Volume	172,500
Average Floor/ Prices per	5.8
NYMEX Roll Swap [Member] | 2013 Settlement Period [Member] | Crude Oil [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	1,875
Total Notional Volume	172,500
Average Floor/ Prices per	-0.18
NYMEX Roll Swap And Basis Swap [Member]	'
Derivative Instruments, Gain (Loss) [Line Items]	'
Notional Daily Volume	'
Total Notional Volume	345,000
Average Floor/ Prices per	'

Commodity_Derivative_Contracts3

Commodity Derivative Contracts - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivative [Line Items]	'	'	'	'
Accumulated other comprehensive income loss before tax	'	'	'	$2,600,000
Accumulated other comprehensive income	-65,000	-65,000	-63,000	1,600,000
Unrealized net gains (losses) reclassified from AOCI, after tax	100,000	200,000	'	'
Scenario, Forecast [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Additional unrealized net gain reclassified from AOCI into earnings	'	200,000	'	'
Additional Reclassification out of Accumulated Other Comprehensive Income [Member] | Scenario, Forecast [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Unrealized net gains (losses) reclassified from AOCI, after tax	'	100,000	'	'
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]	'	'	'	'
Derivative [Line Items]	'	'	'	'
Unrealized net losses reclassified from AOCI into earnings	$200,000	$300,000	'	'

Commodity_Derivative_Contracts4

Commodity Derivative Contracts - Schedule of Derivative Instruments in Statement of Financial Position (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	$17,652	'
Derivatives Not Designated As Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	17,652	20,664
Commodity Contracts [Member] | Current Assets [Member] | Crude Oil [Member] | Derivatives Not Designated As Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	-872	564
Commodity Contracts [Member] | Current Assets [Member] | NGL [Member] | Derivatives Not Designated As Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	6,675	8,361
Commodity Contracts [Member] | Current Assets [Member] | Natural Gas [Member] | Derivatives Not Designated As Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	5,138	5,512
Commodity Contracts [Member] | Non-Current Assets [Member] | Crude Oil [Member] | Derivatives Not Designated As Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	238	3,329
Commodity Contracts [Member] | Non-Current Assets [Member] | NGL [Member] | Derivatives Not Designated As Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	2,128	3,534
Commodity Contracts [Member] | Non-Current Assets [Member] | Natural Gas [Member] | Derivatives Not Designated As Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	5,879	-73
Commodity Contracts [Member] | Current Liabilities [Member] | Crude Oil [Member] | Derivatives Not Designated As Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	-5,424	'
Commodity Contracts [Member] | Current Liabilities [Member] | NGL [Member] | Derivatives Not Designated As Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	1,863	'
Commodity Contracts [Member] | Current Liabilities [Member] | Natural Gas [Member] | Derivatives Not Designated As Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	2,027	'
Commodity Contracts [Member] | Noncurrent Liabilities [Member] | NGL [Member] | Derivatives Not Designated As Hedging Instruments [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Fair value of derivative instruments	'	($563)

Commodity_Derivative_Contracts5

Commodity Derivative Contracts - Schedule of Derivative Gains and Losses in Consolidated Statement of Operations (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Realized gain recognized in income	$1,473	$7,624	$6,764	$16,866
Unrealized (loss) gain recognized in income	-32,070	-35,447	-3,280	19,069
Total commodity derivative (loss) gain recognized in income	-30,597	-27,823	3,484	35,935
Derivative Instruments [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Gain recognized in income	1,473	7,624	6,764	16,866
(Loss) gain recognized in income due to changes in fair value	-32,229	-36,414	-3,012	16,913
Gain (loss) reclassified from Accumulated OCI	$159	$967	($268)	$2,156

Fair_Value_Measurements_Schedu

Fair Value Measurements - Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	$18,687	$21,699
Money Market Funds Asset (Liability) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	1,035	1,035
Commodity Derivative Contracts [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	19,186	21,227
Fair value of assets and liabilities measured on recurring basis	-1,534	-563
Level 1 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	'	'
Level 1 [Member] | Money Market Funds Asset (Liability) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	'	'
Level 1 [Member] | Commodity Derivative Contracts [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	'	'
Fair value of assets and liabilities measured on recurring basis	'	'
Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	1,035	1,035
Level 2 [Member] | Money Market Funds Asset (Liability) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	1,035	1,035
Level 2 [Member] | Commodity Derivative Contracts [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	'	'
Fair value of assets and liabilities measured on recurring basis	'	'
Level 3 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	17,652	20,664
Level 3 [Member] | Money Market Funds Asset (Liability) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	'	'
Level 3 [Member] | Commodity Derivative Contracts [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	25,162	27,554
Fair value of assets and liabilities measured on recurring basis	-7,510	-6,890
Netting [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	'	'
Netting [Member] | Money Market Funds Asset (Liability) [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	'	'
Netting [Member] | Commodity Derivative Contracts [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Fair value of assets and liabilities measured on recurring basis	-5,976	-6,327
Fair value of assets and liabilities measured on recurring basis	$5,976	$6,327

Fair_Value_Measurements_Schedu1

Fair Value Measurements - Schedule of Valuation Process and Unobservable Inputs (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Fair Value, Derivative Asset (Liability)	$17,652
Bbl [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | NYMEX Roll Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Fair Value, Derivative Asset (Liability)	-201
Derivative assets, Valuation Technique(s)	'Discounted cash flow
Unobservable Input	'Forward price curve-NYMEX roll swap
Bbl [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | Basis Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Fair Value, Derivative Asset (Liability)	515
Derivative assets, Valuation Technique(s)	'Discounted cash flow
Unobservable Input	'Forward price curve-basis swap
Bbl [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Fair Value, Derivative Asset (Liability)	-7,247
Derivative assets, Valuation Technique(s)	'Discounted cash flow
Unobservable Input	'Forward price curve-swaps
Bbl [Member] | Derivative Assets [Member] | Crude Oil [Member] | Costless Collar [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Fair Value, Derivative Asset (Liability)	876
Derivative assets, Valuation Technique(s)	'Option model
Unobservable Input	'Forward price curve- costless collar option values
Bbl [Member] | Minimum [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | NYMEX Roll Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	0.48
Bbl [Member] | Minimum [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | Basis Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	2.2
Bbl [Member] | Minimum [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	86.51
Bbl [Member] | Minimum [Member] | Derivative Assets [Member] | Crude Oil [Member] | Costless Collar [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	-2.42
Bbl [Member] | Maximum [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | NYMEX Roll Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	2.05
Bbl [Member] | Maximum [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | Basis Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	3.39
Bbl [Member] | Maximum [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	102.2
Bbl [Member] | Maximum [Member] | Derivative Assets [Member] | Crude Oil [Member] | Costless Collar [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	4.65
Bbl [Member] | Weighted Average [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | NYMEX Roll Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	0.99
Bbl [Member] | Weighted Average [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | Basis Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	2.81
Bbl [Member] | Weighted Average [Member] | Derivative Liabilities [Member] | Crude Oil [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	92.19
Bbl [Member] | Weighted Average [Member] | Derivative Assets [Member] | Crude Oil [Member] | Costless Collar [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	0.48
MMBtu [Member] | Derivative Liabilities [Member] | NGL [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Fair Value, Derivative Asset (Liability)	-62
Derivative assets, Valuation Technique(s)	'Discounted cash flow
Unobservable Input	'Forward price curve-swaps
MMBtu [Member] | Derivative Liabilities [Member] | Natural Gas [Member] | Costless Collar [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Fair Value, Derivative Asset (Liability)	5,671
Derivative assets, Valuation Technique(s)	'Option model
Unobservable Input	'Forward price curve- costless collar option values
MMBtu [Member] | Derivative Liabilities [Member] | Natural Gas [Member] | Natural Gas Swaps [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Fair Value, Derivative Asset (Liability)	7,373
Derivative assets, Valuation Technique(s)	'Discounted cash flow
Unobservable Input	'Forward price curve-swaps
MMBtu [Member] | Derivative Assets [Member] | NGL [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Fair Value, Derivative Asset (Liability)	$10,727
Derivative assets, Valuation Technique(s)	'Discounted cash flow
Unobservable Input	'Forward price curve-swaps
MMBtu [Member] | Minimum [Member] | Derivative Liabilities [Member] | NGL [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	2.07
MMBtu [Member] | Minimum [Member] | Derivative Liabilities [Member] | Natural Gas [Member] | Costless Collar [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	-0.26
MMBtu [Member] | Minimum [Member] | Derivative Liabilities [Member] | Natural Gas [Member] | Natural Gas Swaps [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	3.42
MMBtu [Member] | Minimum [Member] | Derivative Assets [Member] | NGL [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	0.25
MMBtu [Member] | Maximum [Member] | Derivative Liabilities [Member] | NGL [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	2.07
MMBtu [Member] | Maximum [Member] | Derivative Liabilities [Member] | Natural Gas [Member] | Costless Collar [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	0.37
MMBtu [Member] | Maximum [Member] | Derivative Liabilities [Member] | Natural Gas [Member] | Natural Gas Swaps [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	4.26
MMBtu [Member] | Maximum [Member] | Derivative Assets [Member] | NGL [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	2.07
MMBtu [Member] | Weighted Average [Member] | Derivative Liabilities [Member] | NGL [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	2.07
MMBtu [Member] | Weighted Average [Member] | Derivative Liabilities [Member] | Natural Gas [Member] | Costless Collar [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	0.14
MMBtu [Member] | Weighted Average [Member] | Derivative Liabilities [Member] | Natural Gas [Member] | Natural Gas Swaps [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	3.87
MMBtu [Member] | Weighted Average [Member] | Derivative Assets [Member] | NGL [Member] | Swap [Member]	'
Fair Value Assets And Liabilities Measured On Unobservable Inputs [Line Items]	'
Forward Price Curve	0.84

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	9 Months Ended		9 Months Ended		0 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Apr. 15, 2010	Sep. 30, 2013	Apr. 15, 2010	2-May-13	Sep. 30, 2013
			9.500% Senior Notes Due 2018 [Member]	9.500% Senior Notes Due 2018 [Member]	5.625% Senior Notes Due 2021 [Member]	5.625% Senior Notes Due 2021 [Member]
Fair Value Measurements [Line Items]	'	'	'	'	'	'
Fair value of its derivative instruments	$0.10	'	'	'	'	'
Senior notes	'	'	200	200	'	700
Debt instrument, interest rate, stated percentage	'	9.50%	9.50%	'	5.63%	5.63%
Debt maturity date	'	'	'2018	'	'2021	'2021
Carrying amount of total debt	1,175	'	'	'	'	'
Fair market value of total debt	$1,155	'	'	'	'	'

Fair_Value_Measurements_Schedu2

Fair Value Measurements - Schedule of Fair Value Assets and Liabilities Classified (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Schedule Of Fair Value Measurements [Line Items]	'	'	'	'
Balance, Beginning	'	'	$20,664	$4,700
Included in Earnings	'	'	3,752	33,779
Included in Other Comprehensive Income	'	'	'	'
Settlements	-1,473	-7,624	-6,764	-16,866
Purchases	'	'	'	'
Transfers in and out of Level 3	'	'	'	-1,035
Balance, Ending	17,652	20,578	17,652	20,578
Derivatives Asset (Liability) [Member]	'	'	'	'
Schedule Of Fair Value Measurements [Line Items]	'	'	'	'
Balance, Beginning	'	'	20,664	3,665
Included in Earnings	'	'	3,752	33,779
Included in Other Comprehensive Income	'	'	'	'
Settlements	'	'	-6,764	-16,866
Purchases	'	'	'	'
Transfers in and out of Level 3	'	'	'	'
Balance, Ending	17,652	20,578	17,652	20,578
Money Market Funds Asset (Liability) [Member]	'	'	'	'
Schedule Of Fair Value Measurements [Line Items]	'	'	'	'
Balance, Beginning	'	'	'	1,035
Included in Earnings	'	'	'	'
Included in Other Comprehensive Income	'	'	'	'
Settlements	'	'	'	'
Purchases	'	'	'	'
Transfers in and out of Level 3	'	'	'	-1,035
Balance, Ending	'	'	'	'

Asset_Retirement_Obligations_S

Asset Retirement Obligations - Schedule of Asset Retirement Obligations (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Asset Retirement Obligation Disclosure [Abstract]	'
ARO at the beginning of the period	$8,400
Liabilities incurred during period	1,033
Liabilities settled during period	-1,354
Accretion expense	430
ARO at the end of the period	$8,509

Asset_Retirement_Obligations_A

Asset Retirement Obligations - Additional Information (Detail) (USD $)	Sep. 30, 2013
In Millions, unless otherwise specified
Asset Retirement Obligation Disclosure [Abstract]	'
Current portion of ARO	$1.80
Long-term portion of ARO	$6.70

LongTerm_Debt_Additional_Infor

Long-Term Debt - Additional Information (Detail) (USD $)	9 Months Ended		9 Months Ended					0 Months Ended	9 Months Ended
	Sep. 30, 2013	Apr. 15, 2010	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	2-May-13	Sep. 30, 2013	Sep. 30, 2013	Apr. 15, 2010
			Minimum [Member]	Maximum [Member]	Alternative Base Rate [Member]	Alternative Base Rate [Member]	Amended and Restated Senior Revolving Credit Agreement [Member]	5.625% Senior Notes Due 2021 [Member]	5.625% Senior Notes Due 2021 [Member]	9.500% Senior Notes Due 2018 [Member]	9.500% Senior Notes Due 2018 [Member]
					Minimum [Member]	Maximum [Member]
Line of Credit Facility [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Borrowing base increased	$1,500,000,000	'	'	'	'	'	$800,000,000	'	'	'	'
Maturity date	12-Apr-18	'	'	'	'	'	'	'	'	'	'
Amount outstanding	'	'	'	'	'	'	275,000,000	'	'	'	'
Available borrowing capacity	'	'	'	'	'	'	525,000,000	'	'	'	'
Debt instrument, interest rate, stated percentage	'	9.50%	1.50%	2.50%	0.50%	1.50%	'	5.63%	5.63%	9.50%	'
Weighted average borrowing rate under Restated Revolver	3.28%	'	'	'	'	'	'	'	'	'	'
Pre-tax SEC PV-10 reserve value, percentage	80.00%	'	'	'	'	'	'	'	'	'	'
Pledge of membership and limited partnership interests percentage	100.00%	'	'	'	'	'	'	'	'	'	'
Current ratio	2.70%	'	1.00%	'	'	'	'	'	'	'	'
Leverage ratio	2.00%	'	'	4.00%	'	'	'	'	'	'	'
Senior notes	'	'	'	'	'	'	'	'	700,000,000	200,000,000	200,000,000
Debt maturity date	'	'	'	'	'	'	'	'2021	'2021	'2018	'
Redemption of long term debt	'	'	'	'	'	'	'	'	'	104.75	'
Issuance of aggregate principal amount	'	'	'	'	'	'	'	700,000,000	'	'	'
Total outstanding borrowings	$1,175,000,000	'	'	'	'	'	'	'	'	'	'
Weighted average borrowing rate	5.95%	'	'	'	'	'	'	'	'	'	'

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Income Tax Disclosure [Abstract]	'	'	'	'	'
Effective tax rate	36.70%	35.50%	35.50%	36.10%	'
Unrecognized tax benefits	$0	'	$0	'	$0
One-time favorable discrete adjustment	'	'	2.90%	'	'
Effective tax rate excluding discrete item	'	'	36.30%	'	'
Deferred tax asset	$92.80	'	$92.80	'	'

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013
Oil and Gas Delivery Commitments and Contracts [Line Items]	'
Accrued deficiency fees	$6.50
Outstanding commitments	4.6
Minimum remaining contractual commitment	9.5
Reserve related to commercial dispute	$0.50
Oil Commitments (MMBbls) [Member]	'
Oil and Gas Delivery Commitments and Contracts [Line Items]	'
Oil and gas delivery transportation commitments	6,500,000
Natural Gas Commitments (MMBtus) [Member]	'
Oil and Gas Delivery Commitments and Contracts [Line Items]	'
Oil and gas delivery transportation commitments	378,000,000

Commitments_and_Contingencies_2

Commitments and Contingencies - Future Obligations Under Firm Gas and Oil Transportation Agreements (Detail) (USD $)	Sep. 30, 2013
In Thousands, unless otherwise specified
Oil And Gas Delivery Commitments And Contracts Additional Information [Abstract]	'
2013	$8,692
2014	34,486
2015	34,313
2016	33,844
2017	33,388
Thereafter through 2023	133,928
Total future obligations	$278,651

Equity_Schedule_of_Basic_and_D

Equity - Schedule of Basic and Diluted Weighted Average Shares Outstanding (Detail)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]	'	'	'	'
Basic weighted average number of shares outstanding	61,152	52,534	57,656	52,478
Dilution effect of stock option and restricted shares at the end of the period	212	349	268	385
Diluted weighted average number of shares outstanding	61,364	52,883	57,924	52,863
Anti-dilutive stock awards and shares	'	1	'	2

Equity_Additional_Information_

Equity - Additional Information (Detail) (USD $)	9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013
Earnings Per Share [Line Items]	'
Common stock price per share	$42.50
Underwriting discount and structuring fee per share, net	$40.80
Net proceeds from equity issue	$329,008
Underwriters Overallotment Option [Member]	'
Earnings Per Share [Line Items]	'
Public offering of common stock	105,000
Common Stock [Member]	'
Earnings Per Share [Line Items]	'
Public offering of common stock	7,000,000
Net proceeds from equity issue	286,300
Common Stock [Member] | Underwriters Overallotment Option [Member]	'
Earnings Per Share [Line Items]	'
Net proceeds from equity issue	$43,000

StockBased_Compensation_and_Em2

Stock-Based Compensation and Employee Benefits - Schedule of Stock-Based Compensation Expense (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'	'
Total stock-based compensation	$3,621	$6,453	$8,662	$12,258
Capitalized in oil and gas properties	-221	101	-369	-222
Net stock-based compensation expense	$3,400	$6,554	$8,293	$12,036

StockBased_Compensation_and_Em3

Stock-Based Compensation and Employee Benefits - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Stock-based compensation expense recorded	$1.70	$4.60
Unrecognized stock-based compensation expense	10.8	10.8
Percentage of maximum available payout for PSU	'	200.00%
Estimated total compensation expense to be incurred related to PSU awards	'	13.4
Performance Shares [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
PSU award expense	1.9	4
Postretirement Health Care Plans [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Liability related to prior service of employees	'	$0.30

Guarantor_Subsidiaries_Additio

Guarantor Subsidiaries - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2013	Apr. 15, 2010
Guarantor Obligations [Line Items]	'	'
Debt instrument, interest rate, stated percentage	'	9.50%
Number of subsidiaries with restricted assets that exceed 25% of net assets	'None	'
Maximum percentage of non-transferrable net assets	25.00%	'
Senior Notes [Member]	'	'
Guarantor Obligations [Line Items]	'	'
Debt instrument, interest rate, stated percentage	9.50%	'
Five Point Six Two Five Percent Senior Notes [Member]	'	'
Guarantor Obligations [Line Items]	'	'
Debt instrument, interest rate, stated percentage	5.63%	'