Athlon Energy (ATHL) 10-Q 12 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Nov. 12, 2014
Document and Entity Information	'	'
Entity Registrant Name	'Athlon Energy Inc.	'
Entity Central Index Key	'0001574648	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	98,459,476
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$4,997	$113,025
Accounts receivable	97,162	48,238
Derivatives, at fair value	16,948	'
Inventory	1,910	928
Deferred taxes	'	380
Other	2,248	1,166
Total current assets	123,265	163,737
Properties and equipment, at cost - full cost method:	'	'
Evaluated, including wells and related equipment	2,525,499	1,244,178
Unevaluated	678,879	89,859
Accumulated depletion, depreciation, and amortization	-277,347	-160,779
Oil and natural gas properties and equipment, net	2,927,031	1,173,258
Derivatives, at fair value	9,327	2,330
Debt issuance costs	25,101	14,679
Other	2,393	1,447
Total assets	3,087,117	1,355,451
Current liabilities:	'	'
Trade accounts payable	220	459
Accrued liabilities:	'	'
Lease operating	10,631	6,563
Production, severance, and ad valorem taxes	10,462	2,550
Development capital	118,105	68,059
Interest	33,337	7,790
Derivatives, at fair value	'	8,354
Revenue payable	35,233	20,513
Deferred taxes	4,450	'
Other	6,573	4,035
Total current liabilities	219,011	118,323
Asset retirement obligations, net of current portion	12,328	6,795
Long-term debt	1,386,000	500,000
Deferred taxes	141,070	92,397
Other	152	101
Total liabilities	1,758,561	717,616
Commitments and contingencies	'	'
Equity:	'	'
Preferred stock, $0.01 par value, 50,000,000 shares authorized, none issued and outstanding	'	'
Common stock, $0.01 par value, 500,000,000 shares authorized 97,134,446 and 82,129,089 issued and outstanding, respectively	971	821
Additional paid-in capital	1,182,006	593,943
Retained earnings	131,644	32,283
Total stockholders' equity	1,314,621	627,047
Noncontrolling interest	13,935	10,788
Total equity	1,328,556	637,835
Total liabilities and equity	$3,087,117	$1,355,451

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
CONSOLIDATED BALANCE SHEETS	'	'
Preferred stock, par value (in dollars per share)	$0.01	$0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	97,134,446	82,129,089
Common stock, shares outstanding	97,134,446	82,129,089

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Revenues:	'	'	'	'
Oil	$139,925	$75,666	$341,144	$175,934
Natural gas	9,795	4,164	25,907	11,894
Natural gas liquids	16,321	8,595	41,169	20,508
Total revenues	166,041	88,425	408,220	208,336
Production:	'	'	'	'
Lease operating	16,677	8,762	42,126	23,774
Production, severance, and ad valorem taxes	11,647	5,498	27,060	13,549
Depletion, depreciation, and amortization	50,246	23,611	116,792	62,022
General and administrative	15,310	6,696	38,718	13,543
Contract termination fee	'	2,408	'	2,408
Acquisition costs	388	29	2,213	180
Derivative fair value loss (gain)	-58,526	27,037	-14,949	21,331
Accretion of discount on asset retirement obligations	273	174	690	485
Total expenses	36,015	74,215	212,650	137,292
Operating income	130,026	14,210	195,570	71,044
Other income (expenses):	'	'	'	'
Interest	-12,502	-10,039	-35,208	-26,595
Other	36	30	62	30
Total other expenses	-12,466	-10,009	-35,146	-26,565
Income before income taxes	117,560	4,201	160,424	44,479
Income tax provision	42,662	1,934	57,916	6,805
Consolidated net income	74,898	2,267	102,508	37,674
Less: net income (loss) attributable to noncontrolling interest	2,205	-215	3,147	616
Net income attributable to stockholders	$72,693	$2,482	$99,361	$37,058
Net income per common share:	'	'	'	'
Basic (in dollars per share)	$0.74	$0.03	$1.08	$0.53
Diluted (in dollars per share)	$0.74	$0.03	$1.08	$0.53
Weighted average common shares outstanding:	'	'	'	'
Basic (in shares)	97,064	76,637	90,904	69,810
Diluted (in shares)	97,064	78,493	90,904	71,666

CONSOLIDATED_STATEMENT_OF_CHAN

CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (USD $)	Total	Total Stockholders' Equity	Common Stock	Additional Paid-in Capital	Retained Earnings	Noncontrolling Interest
In Thousands, except Share data, unless otherwise specified
Balance at Dec. 31, 2013	$637,835	$627,047	$821	$593,943	$32,283	$10,788
Balance (in shares) at Dec. 31, 2013	82,129,089	'	82,129,000	'	'	'
Increase (Decrease) in Equity	'	'	'	'	'	'
Equity-based compensation	17,726	17,726	'	17,726	'	'
Vesting of stock awards	-3,818	-3,818	2	-3,820	'	'
Vesting of stock awards (in shares)	'	'	199,000	'	'	'
Proceeds from issuance of common stock to the public, net of offering costs	570,760	570,760	148	570,612	'	'
Proceeds from issuance of common stock to the public, net of offering costs (in shares)	'	'	14,806,000	'	'	'
Deferred tax impact of change in noncontrolling interest due to issuance of common stock to the public	3,545	3,545	'	3,545	'	'
Consolidated net income	102,508	99,361	'	'	99,361	3,147
Balance at Sep. 30, 2014	$1,328,556	$1,314,621	$971	$1,182,006	$131,644	$13,935
Balance (in shares) at Sep. 30, 2014	97,134,446	'	97,134,000	'	'	'

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:	'	'
Consolidated net income	$102,508	$37,674
Adjustments to reconcile consolidated net income to net cash provided by operating activities:	'	'
Depletion, depreciation, and amortization	116,792	62,022
Deferred taxes	57,047	6,805
Non-cash derivative loss (gain)	-32,300	13,955
Equity-based compensation	16,006	1,799
Other	3,308	4,756
Changes in operating assets and liabilities, net of effects from acquisitions:	'	'
Accounts receivable	-46,897	-21,350
Other current assets	562	-155
Accounts payable	-239	-702
Accrued interest	25,546	15,968
Revenue payable	14,709	9,718
Other current liabilities	12,717	6,285
Other assets	-90	'
Net cash provided by operating activities	269,669	136,775
Cash flows from investing activities:	'	'
Acquisitions of oil and natural gas properties	-1,365,205	-36,533
Development of oil and natural gas properties	-451,360	-257,984
Other	-1,317	-486
Net cash used in investing activities	-1,817,882	-295,003
Cash flows from financing activities:	'	'
Proceeds from long-term debt, net of issuance costs	1,056,243	629,627
Payments on long-term debt	-183,000	-505,926
Proceeds from issuance of common stock to the public, net of offering costs	570,760	296,044
Distributions to Athlon Holdings LP's Class A limited partners	'	-75,000
Vesting of stock awards	-3,818	'
Other	'	1,500
Net cash provided by financing activities	1,440,185	346,245
Increase (decrease) in cash and cash equivalents	-108,028	188,017
Cash and cash equivalents, beginning of period	113,025	8,871
Cash and cash equivalents, end of period	$4,997	$196,888

Formation_of_the_Company_and_D

Formation of the Company and Description of Business	9 Months Ended
	Sep. 30, 2014
Formation of the Company and Description of Business	'
Formation of the Company and Description of Business	'
	Note 1.         Formation of the Company and Description of Business
	Athlon Energy Inc. (together with its subsidiaries, “Athlon”), a Delaware corporation, was formed on April 1, 2013 and is an independent exploration and production company focused on the acquisition, development, and exploitation of unconventional oil and liquids-rich natural gas reserves in the Permian Basin.
	On April 26, 2013, Athlon Holdings LP (together with its subsidiaries, “Holdings”), a Delaware limited partnership, underwent a corporate reorganization and as a result, Holdings became a majority-owned subsidiary of Athlon.  Holdings is considered Athlon’s accounting predecessor.  Athlon operates and controls all of Holdings’ business and affairs and consolidates its financial results.
	Prior to the corporate reorganization, Holdings was a party to a limited partnership agreement with its management team and certain employees and Apollo Athlon Holdings, L.P. (“Apollo”), which is an affiliate of Apollo Global Management, LLC (“Apollo Global”).  Prior to the corporate reorganization, Apollo Investment Fund VII, L.P. and its parallel funds (the “Apollo Funds”) and Holdings’ management team and certain employees owned all of Holdings’ Class A limited partner interests and Holdings’ management team and certain employees owned all of Holdings’ Class B limited partner interests.
	In the corporate reorganization, the Apollo Funds entered into a number of distribution and contribution transactions pursuant to which the Apollo Funds exchanged their Holdings’ Class A limited partner interests for shares of Athlon’s common stock.  The remaining holders of Holdings’ Class A limited partner interests did not exchange their interests in the reorganization transactions.  In addition, the holders of Holdings’ Class B limited partner interests exchanged their interests for shares of Athlon’s common stock subject to the same conditions and vesting terms.
	Initial Public Offering
	On August 7, 2013, Athlon completed its initial public offering (“IPO”) of 15,789,474 shares of its common stock at $20.00 per share and received net proceeds of approximately $295.7 million, after deducting underwriting discounts and commissions and offering expenses.  Upon closing of the IPO, Holdings’ limited partnership agreement was amended and restated to, among other things, modify Holdings’ capital structure by replacing its different classes of interests with a single new class of units, the “New Holdings Units”.  Holdings’ management team and certain employees that held Class A limited partner interests now own 1,855,563 New Holdings Units and entered into an exchange agreement under which (subject to the terms of the exchange agreement) they have the right to exchange their New Holdings Units for shares of Athlon’s common stock on a one-for-one basis, subject to customary conversion rate adjustments for stock splits, stock dividends, and reclassifications.  Please read “Note 13. Related Party Transactions” for additional discussion.  All other New Holdings Units are held by Athlon.
	Merger with Encana
	On September 27, 2014, Athlon entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Encana Corporation (“Encana”) and Alenco Acquisition Company Inc., Encana’s indirect, wholly owned subsidiary (“Alenco”), pursuant to which Alenco will merge with and into Athlon, with Athlon surviving as an indirect, wholly owned subsidiary of Encana (the “Merger”).  The Merger Agreement, which was unanimously approved by Athlon’s Board of Directors and by Encana’s Board of Directors, provides for Encana’s acquisition of all of the issued and outstanding shares of Athlon’s common stock, par value $0.01 per share, for $58.50 per share in cash (the “Offer”).  Completion of the Merger is conditioned upon, among other things, customary closing conditions.

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2014
Basis of Presentation	'
Basis of Presentation	'
	Note 2.         Basis of Presentation
	Athlon’s consolidated financial statements include the accounts of its wholly owned and majority-owned subsidiaries.  All material intercompany balances and transactions have been eliminated in consolidation.
	In the opinion of management, the accompanying unaudited consolidated financial statements include all adjustments necessary to present fairly, in all material respects, Athlon’s financial position as of September 30, 2014, results of operations for the three and nine months ended September 30, 2014 and 2013, and cash flows for the nine months ended September 30, 2014 and 2013.  All adjustments are of a normal recurring nature.  These interim results are not necessarily indicative of results for an entire year.
	Certain amounts and disclosures have been condensed and omitted from the unaudited consolidated financial statements pursuant to the rules and regulations of the United States Securities and Exchange Commission.  Therefore, these unaudited consolidated financial statements should be read in conjunction with Athlon’s audited consolidated financial statements and related notes thereto included in Athlon’s 2013 Annual Report on Form 10-K.
	Noncontrolling Interest
	As of September 30, 2014 and December 31, 2013, Athlon’s management team and certain employees owned approximately 1.9% and 2.2% of Holdings, respectively.  Holdings’ general partner, Athlon Holdings GP LLC, is a wholly owned subsidiary of Athlon.  Considering the presumption of control, Athlon has fully consolidated the financial position, results of operations, and cash flows of Holdings.
	As presented in the accompanying Consolidated Balance Sheets, “Noncontrolling interest” as of September 30, 2014 and December 31, 2013 of approximately $13.9 million and $10.8 million, respectively, represents Athlon’s management team and certain employees’ ownership of Holdings.  As presented in the accompanying Consolidated Statements of Operations, “Net income (loss) attributable to noncontrolling interest” of approximately $2.2 million and $3.1 million for the three and nine months ended September 30, 2014, respectively, and approximately $(0.2) million and $0.6 million for the three and nine months ended September 30, 2013, respectively, represents Holdings’ net income attributable to Athlon’s management team and certain employees.
	The following table summarizes the effects of changes in Athlon’s partnership interest in Holdings on Athlon’s equity for the periods indicated:
		Three months ended				Nine months ended
		September 30,				September 30,
		2014		2013		2014		2013
		(in thousands)
	Net income attributable to stockholders	$	72,693	$	2,482	$	99,361	$	37,058
	Transfer from noncontrolling interest:
	Increase in Athlon’s paid-in capital for deferred tax impact of change in noncontrolling interest due to issuance of common stock to the public	4,155		—		3,545		—
	Increase in Athlon’s paid-in capital for corporate reorganization	—		—		—		290,950
	Increase in Athlon’s paid-in capital for issuance of common stock to the public	63		295,473		570,612		295,473
	Net transfer from noncontrolling interest	4,218		295,473		574,157		586,423
	Change from net income attributable to stockholders and transfers from noncontrolling interest	$	76,911	$	297,955	$	673,518	$	623,481
	New Accounting Pronouncements
	In May 2014, the Financial Accounting Standards Board issued Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers”.  ASU 2014-09 supersedes most of the existing revenue recognition requirements in accounting principles generally accepted in the United States (“GAAP”) and requires (i) an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration the entity expects to be entitled to in exchange for those goods or services and (ii) requires expanded disclosures regarding the nature, amount, timing, and certainty of revenue and cash flows from contracts with customers.  ASU 2014-09 is effective retrospectively for annual and interim reporting periods beginning after December 15, 2016, with early application not permitted.  Athlon is evaluating the impact, if any, that the adoption of ASU 2014-09 will have on its financial position, results of operations, and liquidity.
	No other new accounting pronouncements issued or effective from January 1, 2014 through the date of this Report, had or are expected to have a material impact on Athlon’s unaudited consolidated financial statements.

Acquisitions

Acquisitions	9 Months Ended
	Sep. 30, 2014
Acquisitions	'
Acquisitions	'
	Note 3.         Acquisitions
	On June 2, 2014, Athlon acquired certain oil and natural gas properties and related assets in the Midland Basin from Hibernia Holdings, LLC (“Hibernia”) for approximately $394.0 million in cash, which was financed with a portion of the net proceeds from debt and equity offerings.  Please read “Note 7. Long-Term Debt” and “Note 8. Stockholders’ Equity” for additional discussion of these offerings.  The operations of these properties have been included in the accompanying Consolidated Statements of Operations with those of Athlon from the date of acquisition.  Athlon has included revenues of $30.3 million and direct operating expenses of $3.5 million for the period June 2, 2014 to September 30, 2014 due to the Hibernia acquisition in the accompanying Consolidated Statements of Operations.  The disclosure of net earnings is impracticable to calculate due to the full cost method of depletion.  Athlon incurred approximately $0.7 million of transaction costs related to the Hibernia acquisition, which are included in “Acquisition costs” in the accompanying Consolidated Statements of Operations.
	On June 3, 2014, Athlon acquired certain oil and natural gas properties and related assets in the Midland Basin from Piedra Energy II, LLC (“Piedra”) for approximately $292.8 million in cash, which was financed with a portion of the net proceeds from debt and equity offerings.  Please read “Note 7. Long-Term Debt” and “Note 8. Stockholders’ Equity” for additional discussion of these offerings.  The operations of these properties have been included in the accompanying Consolidated Statements of Operations with those of Athlon from the date of acquisition.  Athlon has included revenues of $12.4 million and direct operating expenses of $1.8 million for the period June 3, 2014 to September 30, 2014 due to the Piedra acquisition in the accompanying Consolidated Statements of Operations.  The disclosure of net earnings is impracticable to calculate due to the full cost method of depletion.  Athlon incurred approximately $0.6 million of transaction costs related to the Piedra acquisition, which are included in “Acquisition costs” in the accompanying Consolidated Statements of Operations.
	On August 28, 2014, Athlon acquired certain oil and natural gas properties and related assets in the Midland Basin from Summit West Resources LP and Summit Group (“Summit”) for approximately $202.5 million in cash, which was financed with cash on hand and borrowings under Athlon’s credit agreement.  The operations of these properties have been included in the accompanying Consolidated Statements of Operations with those of Athlon from the date of acquisition.  Athlon has included revenues of $2.4 million and direct operating expenses of $0.5 million for the period August 28, 2014 to September 30, 2014 due to the Summit acquisition in the accompanying Consolidated Statements of Operations.  The disclosure of net earnings is impracticable to calculate due to the full cost method of depletion.  Athlon incurred approximately $0.1 million of transaction costs related to the Summit acquisition, which are included in “Acquisition costs” in the accompanying Consolidated Statements of Operations.
	Based on currently available information, the estimated allocation of the purchase price to the fair value of the assets acquired and liabilities assumed from Hibernia, Piedra, and Summit was as follows as of September 30, 2014:
		Hibernia		Piedra		Summit		Total
		(in thousands)
	Evaluated, including wells and related equipment	$	248,363	$	173,317	$	93,899	$	515,579
	Unevaluated	145,984		119,504		109,570		375,058
	Inventory	499		759		132		1,390
	Total assets acquired	394,846		293,580		203,601		892,027
	Other current liabilities	107		289		659		1,055
	Asset retirement obligations	706		536		437		1,679
	Total liabilities assumed	813		825		1,096		2,734
	Fair value of net assets acquired	$	394,033	$	292,755	$	202,505	$	889,293
	At September 30, 2014, Athlon was awaiting final close on the Hibernia and Summit acquisitions, which will contain certain customary purchase price adjustments.
	The following unaudited pro forma condensed financial data was derived from the historical financial statements of Athlon and from the accounting records of Hibernia, Piedra, and Summit to give effect to the acquisitions as if they had occurred on January 1, 2013.  The unaudited pro forma condensed financial information has been included for comparative purposes only and is not necessarily indicative of the results that might have occurred had the acquisitions taken place on January 1, 2013 and is not intended to be a projection of future results.
		Three months ended September 30,				Nine months ended September 30,
		2014		2013		2014		2013
		(in thousands, except per share amounts)
	Pro forma total revenues	$	171,740	$	116,169	$	471,830	$	271,420
	Pro forma net income attributable to stockholders	$	75,259	$	4,398	$	111,592	$	38,197
	Pro forma net income per common share:
	Basic	$	0.76	$	0.05	$	1.14	$	0.45
	Diluted	$	0.76	$	0.05	$	1.14	$	0.45

Evaluated_Properties

Evaluated Properties	9 Months Ended
	Sep. 30, 2014
Evaluated Properties	'
Evaluated Properties	'
	Note 4. Evaluated Properties
	Amounts shown in the accompanying Consolidated Balance Sheets as “Evaluated, including wells and related equipment” consisted of the following as of the dates indicated:
		September 30,		December 31,
		2014		2013
		(in thousands)
	Evaluated leasehold costs	$	1,156,611	$	448,689
	Wells and related equipment - completed	1,314,766		748,900
	Wells and related equipment - in process	54,122		46,589
	Total evaluated	$	2,525,499	$	1,244,178

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2014
Fair Value Measurements	'
Fair Value Measurements	'
	Note 5.  Fair Value Measurements
	The book values of cash and cash equivalents, accounts receivable, and accounts payable approximate fair value due to the short-term nature of these instruments.  Commodity derivative contracts are marked-to-market each quarter and are thus stated at fair value in the accompanying Consolidated Balance Sheets.  As of September 30, 2014, the fair value of Athlon’s 73/8% senior notes due 2021 was approximately $542.5 million and the fair value of Athlon’s 6% senior notes due 2022 was approximately $698.8 million using open market quotes (“Level 1” input).
	Derivative Policy
	Athlon uses various financial instruments for non-trading purposes to manage and reduce price volatility and other market risks associated with its oil production.  These arrangements are structured to reduce Athlon’s exposure to commodity price decreases, but they can also limit the benefit Athlon might otherwise receive from commodity price increases.  Athlon’s risk management activity is generally accomplished through over-the-counter commodity derivative contracts with large financial institutions, most of which are lenders under Athlon’s credit agreement.
	Athlon applies the provisions of the “Derivatives and Hedging” topic of the Accounting Standards Codification, which requires each derivative instrument to be recorded in the accompanying Consolidated Balance Sheets at fair value.  If a derivative has not been designated as a hedge or does not otherwise qualify for hedge accounting, it must be adjusted to fair value through earnings.  Athlon elected not to designate its current portfolio of commodity derivative contracts as hedges for accounting purposes.  Therefore, changes in fair value of these derivative instruments are recognized in earnings and included in “Derivative fair value loss (gain)” in the accompanying Consolidated Statements of Operations.
	Athlon enters into commodity derivative contracts for the purpose of economically fixing the price of its anticipated oil production even though Athlon does not designate the derivatives as hedges for accounting purposes.  Athlon classifies cash flows related to derivative contracts based on the nature and purpose of the derivative.  As the derivative cash flows are considered an integral part of Athlon’s oil and natural gas operations, they are classified as cash flows from operating activities in the accompanying Consolidated Statements of Cash Flows.
	Commodity Derivative Contracts
	Commodity prices are often subject to significant volatility due to many factors that are beyond Athlon’s control, including but not limited to: prevailing economic conditions, supply and demand of hydrocarbons in the marketplace, actions by speculators, and geopolitical events such as wars or natural disasters.  Athlon manages oil price risk with swaps, which provide a fixed price for a notional amount of sales volumes.  The following table summarizes Athlon’s open commodity derivative contracts as of September 30, 2014:
	Period	Average		Weighted-			Net Asset Fair
		Daily		Average			Market Value
		Swap		Swap Price
		Volume
		(Bbl)		(per Bbl)			(in thousands)
	Q4 2014	10,961		$	92.31		$	2,168
	Q1 2015	12,800		92.12
	Q2 2015	12,800		92.12
	Q3 2015	11,800		93.69
	Q4 2015	11,800		93.69
	2015	12,296		92.88			22,727
	Q1 2016	2,500		92.35
	Q2 2016	2,500		92.35
	2016	1,243		92.35			2,718
							$	27,613
	Athlon is also a party to Midland-Cushing basis differential swaps for 6,000 Bbls/D at $5.19/Bbl for 2015.  At September 30, 2014, the fair value of these contracts was a net liability of approximately $1.3 million.
	Counterparty Risk. At September 30, 2014, Athlon had committed 10% or greater (in terms of fair market value) of its oil derivative contracts in asset positions from the following counterparties:
		Fair Market Value of
		Oil Derivative
		Contracts
	Counterparty	Committed
		(in thousands)
	Citibank	$	7,524
	Barclays PLC	6,187
	Scotiabank	4,953
	J Aron	4,397
	Athlon does not require collateral from its counterparties for entering into derivative instruments, so in order to mitigate the credit risk associated with such derivative instruments, Athlon enters into an International Swap Dealers Association Master Agreement (“ISDA Agreement”) with each of its counterparties.  The ISDA Agreement is a standardized, bilateral contract between a given counterparty and Athlon.  Instead of treating each derivative transaction between the counterparty and Athlon separately, the termination provision of the ISDA Agreement enables the counterparty and Athlon to aggregate all trades under such agreement and treat them as a single agreement.  This arrangement is intended to benefit Athlon in two ways: (i) default by a counterparty under a single trade can trigger rights to terminate all trades with such counterparty that are subject to the ISDA Agreement; and (ii) netting of settlement amounts reduces Athlon’s credit exposure to a given counterparty in the event of close-out.  Athlon’s accounting policy is to not offset fair value amounts between different counterparties for derivative instruments in the accompanying Consolidated Balance Sheets.
	Tabular Disclosures of Fair Value Measurements
	The following table summarizes the fair value of Athlon’s derivative instruments not designated as hedging instruments as of the dates indicated:
		Oil			Commodity			Total
	Balance Sheet	Commodity			Derivatives			Commodity
	Location	Derivatives			Netting (a)			Derivatives
		(in thousands)
	As of September 30, 2014
	Assets
	Derivatives - current	$	17,751		$	(803	)	$	16,948
	Derivatives - noncurrent	9,940			(613		)	9,327
	Total assets	27,691			(1,416		)	26,275
	Liabilities
	Derivatives - current	(803		)	803			—
	Derivatives - noncurrent	(613		)	613			—
	Total liabilities	(1,416		)	1,416			—
	Net asset	$	26,275		$	—		$	26,275
	As of December 31, 2013
	Assets
	Derivatives - current	$	143		$	(143	)	$	—
	Derivatives - noncurrent	2,330			—			2,330
	Total assets	2,473			(143		)	2,330
	Liabilities
	Derivatives - current	(8,497		)	143			(8,354		)
	Derivatives - noncurrent	—			—			—
	Total liabilities	(8,497		)	143			(8,354		)
	Net liability	$	(6,024	)	$	—		$	(6,024	)
	(a)     Represents counterparty netting under ISDA Agreements, which allow for netting of commodity derivative contracts.  These derivative instruments are reflected net on the accompanying Consolidated Balance Sheets.
	The following table summarizes the effect of derivative instruments not designated as hedges on the accompanying Consolidated Statements of Operations for the periods indicated:
			Amount of Loss (Gain) Recognized in Income
	Location of Loss (Gain)		Three months ended September 30,						Nine months ended September 30,
Derivatives Not Designated as Hedges	Recognized in Income		2014			2013			2014			2013
			(in thousands)
Commodity derivative contracts	Derivative fair value loss (gain)		$	(58,526	)	$	27,037		$	(14,949	)	$	21,331
Fair Value Hierarchy
Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.  GAAP establishes a three-tier fair value hierarchy, which prioritizes the inputs used to measure fair value.  The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements).  The three levels of the fair value hierarchy are defined as follows:
·         Level 1 — Inputs such as unadjusted, quoted prices that are available in active markets for identical assets or liabilities.
·         Level 2 — Inputs, other than quoted prices within Level 1, that are either directly or indirectly observable, such as quoted prices for similar assets and liabilities or quoted prices in inactive markets.
·         Level 3 — Inputs that are unobservable for use when little or no market data exists requiring the use of valuation methodologies that result in management’s best estimate of fair value.
As required by GAAP, Athlon utilizes the most observable inputs available for the valuation technique used.  The financial assets and liabilities are classified in their entirety based on the lowest level of input that is of significance to the fair value measurement.  Athlon’s assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the valuation of the financial assets and liabilities and their placement within the fair value hierarchy levels.  The following methods and assumptions were used to estimate the fair values of Athlon’s assets and liabilities that are accounted for at fair value on a recurring basis:
·         Level 2 — Fair values of swaps are estimated using a combined income-based and market-based valuation methodology based upon forward commodity price curves obtained from independent pricing services.  Settlement is determined by the average underlying price over a predetermined period of time.  Athlon uses observable inputs to determine fair value such as: (i) current market and contractual prices for the underlying instruments; (ii) quoted forward prices for oil; (iii) interest rates, such as a LIBOR curve for a term similar to the commodity derivative contract; and (iv) appropriate volatilities.
Athlon adjusts the valuations from the valuation model for nonperformance risk.  For commodity derivative contracts which are in an asset position, Athlon adds the counterparty’s credit default swap spread to the risk-free rate.  If a counterparty does not have a credit default swap spread, Athlon uses other companies with similar credit ratings to determine the applicable spread.  For commodity derivative contracts which are in a liability position, Athlon uses the yield on its senior notes less the risk-free rate.  All fair values have been adjusted for nonperformance risk resulting in a decrease in the net commodity derivative asset of approximately $56,000 as of September 30, 2014 and a decrease in the net commodity derivative liability of approximately $39,000 as of December 31, 2013.
The following table sets forth Athlon’s assets and liabilities that were accounted for at fair value on a recurring basis as of the dates indicated:
				Fair Value Measurements at Reporting Date Using
				Quoted Prices in
				Active Markets for			Significant Other			Significant
				Identical Assets			Observable Inputs			Unobservable Inputs
Description	Net Asset/(Liability)			(Level 1)			(Level 2)			(Level 3)
	(in thousands)
As of September 30, 2014
Oil derivative contracts - swaps	$	27,613		$	—		$	27,613		$	—
Oil derivative contracts - basis differential swaps	(1,338		)	—			(1,338		)	—
Total	$	26,275		$	—		$	26,275		$	—
As of December 31, 2013
Oil derivative contracts - swaps	$	(6,024	)	$	—		$	(6,024	)	$	—

Asset_Retirement_Obligations

Asset Retirement Obligations	9 Months Ended
	Sep. 30, 2014
Asset Retirement Obligations	'
Asset Retirement Obligations	'
	Note 6. Asset Retirement Obligations
	Asset retirement obligations relate to future plugging and abandonment expenses on oil and natural gas properties and related facilities disposal.  The following table summarizes the changes in Athlon’s asset retirement obligations for the nine months ended September 30, 2014 (in thousands):
	Balance at January 1	$	6,855
	Liabilities assumed in acquisitions	3,140
	Liabilities incurred from new wells	1,463
	Liabilities settled	(103		)
	Accretion of discount	690
	Revisions of previous estimates	292
	Balance at September 30	12,337
	Less: current portion	9
	Asset retirement obligations - long-term	$	12,328

LongTerm_Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2014
Long-Term Debt.	'
Long-Term Debt	'
	Note 7. Long-Term Debt
	Long-term debt consisted of the following as of the dates indicated:
		Maturity		September 30,			December 31,
		Date		2014			2013
				(in thousands)
	Credit agreement	3/19/18		$	236,000		$	—
	73/8% senior notes	4/15/21		500,000			500,000
	6% senior notes	5/1/22		650,000			—
	Total			$	1,386,000		$	500,000
	Senior Notes
	In April 2013, Holdings issued $500 million aggregate principal amount of 73/8% senior unsecured notes due 2021 (the “2021 Notes”).  Athlon is an unconditional guarantor of the 2021 Notes.  Under the indenture, starting on April 15, 2016, Athlon will be able to redeem some or all of the 2021 Notes at a premium that will decrease over time, plus accrued and unpaid interest to the date of redemption.  Prior to April 15, 2016, Athlon will be able, at its option, to redeem up to 35% of the aggregate principal amount of the 2021 Notes at a price of 107.375% of the principal thereof, plus accrued and unpaid interest to the date of redemption, with an amount equal to the net proceeds from certain equity offerings.  In addition, at Athlon’s option, prior to April 15, 2016, Athlon may redeem some or all of the 2021 Notes at a redemption price equal to 100% of the principal amount of the 2021 Notes, plus an “applicable premium”, plus accrued and unpaid interest to the date of redemption.  Certain asset dispositions or a change in control will be triggering events that may require Athlon to repurchase all or any part of a noteholder’s 2021 Notes at a purchase price in cash equal to 101% of the principal amount thereof, plus accrued and unpaid interest, if any, to but excluding the date of repurchase.  Interest on the 2021 Notes is payable in cash semi-annually in arrears, commencing on October 15, 2013, through maturity.
	On May 1, 2014, Holdings completed a private placement of $650 million aggregate principal amount of 6% senior unsecured notes due 2022 (the “2022 Notes”) and received net proceeds of approximately $639.1 million, after deducting initial purchasers’ discounts and debt issuance costs.  Athlon is an unconditional guarantor of the 2022 Notes.  Under the indenture, starting on May 1, 2017, Athlon will be able to redeem some or all of the 2022 Notes at a premium that will decrease over time, plus accrued and unpaid interest to the date of redemption.  Prior to May 1, 2017, Athlon will be able, at its option, to redeem up to 35% of the aggregate principal amount of the 2022 Notes at a price of 106% of the principal thereof, plus accrued and unpaid interest to the date of redemption, with an amount equal to the net proceeds from certain equity offerings.  In addition, at Athlon’s option, prior to May 1, 2017, Athlon may redeem some or all of the 2022 Notes at a redemption price equal to 100% of the principal amount of the 2022 Notes, plus an “applicable premium”, plus accrued and unpaid interest to the date of redemption.  If a change of control occurs on or prior to July 15, 2015, Athlon may redeem all, but not less than all, of the 2022 Notes at 110% of the principal amount thereof plus accrued and unpaid interest to, but not including, the redemption date.  Certain asset dispositions or a change of control that occurs after July 15, 2015 will be triggering events that may require Athlon to repurchase all or any part of a noteholder’s 2022 Notes at a purchase price in cash equal to 101% of the principal amount thereof, plus accrued and unpaid interest, if any, up to but excluding the date of repurchase.  Interest on the 2022 Notes is payable in cash semi-annually in arrears, commencing on November 1, 2014, through maturity.
	The indentures governing Athlon’s senior notes contain covenants, including, among other things, covenants that restrict Athlon’s ability to:
	·         make distributions, investments, or other restricted payments if Athlon’s fixed charge coverage ratio is less than 2.0 to 1.0;
	·         incur additional indebtedness if Athlon’s fixed charge coverage ratio would be less than 2.0 to 1.0; and
	·         create liens, sell assets, consolidate or merge with any other person, or engage in transactions with affiliates.
	These covenants are subject to a number of important qualifications, limitations, and exceptions.  In addition, the indenture contains other customary terms, including certain events of default upon the occurrence of which Athlon’s senior notes may be declared immediately due and payable.
	As of September 30, 2014, Athlon was in compliance with all covenants of its senior notes.
	Credit Agreement
	Athlon is a party to an amended and restated credit agreement dated March 19, 2013 (the “Credit Agreement”), which matures on March 19, 2018.  The Credit Agreement provides for revolving credit loans to be made to Athlon from time to time and letters of credit to be issued from time to time for the account of Athlon or any of its restricted subsidiaries.  The aggregate amount of the commitments of the lenders under the Credit Agreement is $1.0 billion.  Availability under the Credit Agreement is subject to a borrowing base, which is redetermined semi-annually and upon requested special redeterminations.  Borrowings under the Credit Agreement may be repaid from time to time without penalty.  As of September 30, 2014, the borrowing base was $837.5 million and there were $236 million of outstanding borrowings, $601.5 million of borrowing capacity, and no outstanding letters of credit under the Credit Agreement.
	Obligations under the Credit Agreement are secured by a first-priority security interest in substantially all of Holdings’ proved reserves.
	Loans under the Credit Agreement are subject to varying rates of interest based on (i) outstanding borrowings in relation to the borrowing base and (ii) whether the loan is a Eurodollar loan or a base rate loan.  Eurodollar loans under the Credit Agreement bear interest at the Eurodollar rate plus the applicable margin indicated in the following table, and base rate loans under the Credit Agreement bear interest at the base rate plus the applicable margin indicated in the following table.  Athlon also incurs a quarterly commitment fee on the unused portion of the Credit Agreement indicated in the following table:
	Ratio of Outstanding Borrowings to Borrowing Base	Unused		Applicable		Applicable
		Commitment Fee		Margin for		Margin for Base
				Eurodollar Loans		Rate Loans
	Less than or equal to .30 to 1	0.375	%	1.5	%	0.5	%
	Greater than .30 to 1 but less than or equal to .60 to 1	0.375	%	1.75	%	0.75	%
	Greater than .60 to 1 but less than or equal to .80 to 1	0.5	%	2	%	1	%
	Greater than .80 to 1 but less than or equal to .90 to 1	0.5	%	2.25	%	1.25	%
	Greater than .90 to 1	0.5	%	2.5	%	1.5	%
	The “Eurodollar rate” for any interest period (either one, two, three, or six months, as selected by Athlon) is the rate equal to the British Bankers Association London Interbank Offered Rate (“LIBOR”) for deposits in dollars for a similar interest period.  The “Base Rate” is calculated as the highest of: (i) the annual rate of interest announced by Bank of America, N.A. as its “prime rate”; (ii) the federal funds effective rate plus 0.5%; or (iii) except during a “LIBOR Unavailability Period”, the Eurodollar rate (for dollar deposits for a one-month term) for such day plus 1.0%.
	The Credit Agreement contains covenants including, among others, the following:
	·         a prohibition against incurring additional debt, subject to permitted exceptions;
	·         a restriction on creating liens on Athlon’s assets and the assets of its operating subsidiaries, subject to permitted exceptions;
	·         restrictions on merging and selling assets outside the ordinary course of business;
	·         restrictions on use of proceeds, investments, transactions with affiliates, or change of principal business;
	·         a requirement that Athlon maintain a ratio of consolidated total debt to EBITDAX (as defined in the Credit Agreement) of not more than 4.5 to 1.0; and
	·         a provision limiting commodity derivative contracts to a volume not exceeding 85% of projected production from proved reserves for a period not exceeding 66 months from the date the commodity derivative contract is entered into.
	As of September 30, 2014, Athlon was in compliance with all covenants of the Credit Agreement.
	The Credit Agreement contains customary events of default, including our failure to comply with the financial ratios described above, which would permit the lenders to accelerate the debt if not cured within applicable grace periods.  If an event of default occurs and is continuing, lenders with a majority of the aggregate commitments may require Bank of America, N.A. to declare all amounts outstanding under the Credit Agreement to be immediately due and payable.

Stockholders_Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2014
Stockholders' Equity	'
Stockholders' Equity	'
	Note 8. Stockholders’ Equity
	On April 23, 2014, Athlon completed a public offering of 14,806,250 shares of its common stock at $40.00 per share and received net proceeds of approximately $570.8 million, after deducting underwriting discounts and commissions and offering expenses.  Upon consummation of the offering, Athlon’s ownership percentage of Holdings increased, resulting in a decrease in the noncontrolling interest from approximately 2.2% to approximately 1.9%.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2014
Income Taxes	'
Income Taxes	'
	Note 9.         Income Taxes
	As a result of the corporate reorganization on April 26, 2013, Athlon (a C-corporation) obtained substantially all of Holdings’ interests, Athlon’s accounting predecessor, which is a limited partnership not subject to federal income taxes.
	The components of income tax provision were as follows for the periods indicated:
		Nine months ended
		September 30,
		2014			2013
		(in thousands)
	Federal:
	Current	$	869		$	—
	Deferred	54,992			6,202
	Total federal	55,861			6,202
	State, net of federal benefit:
	Deferred	2,055			603
	Total state	2,055			603
	Income tax provision	$	57,916		$	6,805
	The following table reconciles income tax provision with income tax at the Federal statutory rate for the periods indicated:
		Nine months ended September 30,
		2014			2013
		(in thousands)
	Income before income taxes	$	160,424		$	44,479
	Less: net income prior to corporate reorganization	—			(26,780		)
	Less: net income attributable to noncontrolling interest	(3,147		)	(616		)
	Income before income taxes and noncontrolling interest subsequent to corporate reorganization	$	157,277		$	17,083
	Income taxes at the Federal statutory rate	$	55,047		$	5,979
	State income taxes, net of federal benefit	2,055			603
	Provision to return adjustment	191			59
	Permanent and other	623			164
	Income tax provision	$	57,916		$	6,805
	As of September 30, 2014 and December 31, 2013, all of Athlon’s tax positions met the “more-likely-than-not” threshold.  During the nine months ended September 30, 2014 and 2013, Athlon did not have any interest assessed by the taxing authorities or incur any penalties related to income taxes.

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2014
Earnings Per Share	'
Earnings Per Share	'
	Note 10. Earnings Per Share
	Prior to the consummation of the IPO, Athlon had 960,907 shares of outstanding common stock.  In conjunction with the closing of the IPO, certain of Holdings’ Class A and Class B limited partners that exchanged their interests for shares of Athlon’s common stock were subject to an adjustment based on the IPO price of $20.00 per share and an actual 65.266-for-1 stock split.  Following this adjustment and stock split, the number of outstanding shares of Athlon’s common stock increased from 960,907 shares to 66,339,615 shares.  The one-to-one conversion of Holdings’ interests in April 2013 to 960,907 shares of Athlon’s common stock is akin to a stock split and has been treated as such in Athlon’s earnings per share (“EPS”) calculations.  Accordingly, Athlon assumes that 66,339,615 shares of common stock were outstanding during periods prior to the IPO for purposes of calculating EPS.
	The following table reflects the allocation of net income to common stockholders and EPS computations for the periods indicated:
		Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
		(in thousands, except per share amounts)
	Basic EPS
	Numerator:
	Undistributed net income attributable to stockholders	$	72,693		$	2,482		$	99,361		$	37,058
	Participation rights of unvested stock awards in undistributed earnings	(1,135		)	(6		)	(1,147		)	(6		)
	Basic undistributed net income attributable to stockholders	$	71,558		$	2,476		$	98,214		$	37,052
	Denominator:
	Basic weighted average shares outstanding	97,064			76,637			90,904			69,810
	Basic EPS attributable to stockholders	$	0.74		$	0.03		$	1.08		$	0.53
	Diluted EPS
	Numerator:
	Undistributed net income attributable to stockholders	$	72,693		$	2,482		$	99,361		$	37,058
	Participation rights of unvested stock awards in undistributed earnings	(1,135		)	(6		)	(1,147		)	(6		)
	Effect of conversion of New Holdings Units to shares of Athlon’s common stock (a)	—			(215		)	—			616
	Diluted undistributed net income attributable to stockholders	$	71,558		$	2,261		$	98,214		$	37,668
	Denominator:
	Basic weighted average shares outstanding	97,064			76,637			90,904			69,810
	Effect of conversion of New Holdings Units to shares of Athlon’s common stock (a)	—			1,856			—			1,856
	Diluted weighted average shares outstanding	97,064			78,493			90,904			71,666
	Diluted EPS attributable to stockholders	$	0.74		$	0.03		$	1.08		$	0.53
	(a)     For the three and nine months ended September 30, 2014, 1,855,563 New Holdings Units were outstanding but excluded from the EPS calculations because their effect would have been antidilutive.

Incentive_Stock_Plans

Incentive Stock Plans	9 Months Ended
	Sep. 30, 2014
Incentive Stock Plans	'
Incentive Stock Plans	'
	Note 11.  Incentive Stock Plans
	In August 2013, Athlon adopted the Athlon Energy Inc. 2013 Incentive Award Plan (the “Plan”).  The principal purpose of the Plan is to attract, retain, and engage selected employees, consultants, and directors through the granting of equity and equity-based compensation awards.  Employees, consultants, and directors of Athlon and its subsidiaries are eligible to receive awards under the Plan.  The Compensation Committee will administer the Plan unless the Board of Directors assumes direct authority for administration.  The Plan provides for the grant of stock options (including non-qualified stock options and incentive stock options), restricted stock, dividend equivalents, stock payments, restricted stock units, performance awards, stock appreciation rights, and other equity-based and cash-based awards, or any combination thereof.
	The initial aggregate number of shares of common stock reserved for issuance pursuant to awards granted under the Plan is the sum of 8,400,000 shares, subject to adjustment as described below plus an annual increase on the first day of each calendar year beginning January 1, 2014 and ending on and including the last January 1 prior to the expiration date of the Plan, equal to the lessor of (i) 12,000,000 shares, (ii) 4% of the shares outstanding (on an as-converted basis) on the final day of the immediately preceding calendar year, and (iii) such smaller number of shares as determined by the Board of Directors.  This number will also be adjusted due to the following shares becoming eligible to be used again for grants under the Plan:
	·         shares subject to awards or portions of awards granted under the Plan which are forfeited, expire, or lapse for any reason, or are settled for cash without the delivery of shares, to the extent of such forfeiture, expiration, lapse, or cash settlement; and
	·         shares that Athlon repurchases prior to vesting so that such shares are returned to Athlon.
	On January 1, 2014, the aggregate number of shares of common stock reserved for issuance pursuant to awards granted under the Plan increased to 11,759,386.  As of September 30, 2014, there were 9,815,681 shares available for issuance under the Plan.
	The Plan does not provide for individual limits on awards that may be granted to any individual participant under the Plan.  Rather, the amount of awards to be granted to individual participants are determined by the Board of Directors or the Compensation Committee from time to time, as part of their compensation decision-making processes, provided, however, that the Plan does not permit awards having a grant date fair value in excess of $700,000 to be granted to Athlon’s non-employee directors in any year.
	During the nine months ended September 30, 2014 and 2013, Athlon recorded non-cash equity-based compensation expense related to the Plan of $16.0 million and $0.5 million, respectively, which was allocated to lease operating expense and general and administrative expense in the accompanying Consolidated Statements of Operations based on the allocation of the respective employees’ compensation.  During the nine months ended September 30, 2014 and 2013, Athlon capitalized non-cash equity-based compensation expense related to the Plan of $1.7 million and $37,000, respectively, as a component of “Evaluated, including wells and related equipment” in the accompanying Consolidated Balance Sheets.
	Stock awards are scheduled to vest over three years.  Certain awards granted to Athlon’s management team vest subject to the relative performance of Athlon’s common stock to that of a designated peer group.  The following table summarizes the changes in Athlon’s unvested stock awards for the nine months ended September 30, 2014 (presented at the target level):
				Weighted -
				Average
		Number of		Grant Date
		Shares		Fair Value
	Outstanding at January 1	638,913		$	34.88
	Granted	1,317,907		45.03
	Vested	(209,540	)	37.8
	Forfeited	(13,114	)	32.01
	Outstanding at September 30	1,734,166		42.27
	As of September 30, 2014, there were 1,139,907 unvested stock awards, 872,444 of which were granted during 2014, in which the vesting is dependent only on the passage of time and continued employment.  Additionally, as of September 30, 2014, there were 594,259 unvested stock awards, 442,592 of which were granted during 2014, in which the vesting is dependent not only on the passage of time and continued employment, but also on the relative performance of Athlon’s common stock to that of a designated peer group (presented at the target level).
	During the nine months ended September 30, 2014, there were 285,373 stock awards that vested for which Athlon withheld 86,266 shares of common stock to satisfy employees’ minimum tax withholding obligations related thereto.  The total fair value of stock awards that vested during the nine months ended September 30, 2014 was $12.7 million.
	None of Athlon’s unvested stock awards are subject to variable accounting.  As of September 30, 2014, Athlon had approximately $53.9 million of total unrecognized compensation cost related to unvested stock awards, which is expected to be recognized over a weighted-average period of approximately 2.7 years.
	Class B Interests
	Holdings’ limited partnership agreement provided for the issuance of Class B limited partner interests.  As discussed in “Note 1. Formation of the Company and Description of Business”, in connection with the corporate reorganization, Holdings’ Class B limited partners exchanged their interests for shares of Athlon’s common stock subject to the same conditions and vesting terms.  Upon the consummation of the IPO on August 1, 2013, the remaining unvested common stock awards, which were formerly Holdings’ Class B interests, vested and Athlon recognized non-cash equity-based compensation expense of approximately $1.2 million, which was allocated to lease operating expense and general and administrative expenses in the accompanying Consolidated Statements of Operations based on the allocation of the respective employees’ compensation, and capitalized non-cash equity-based compensation expense of $0.4 million as a component of “Evaluated, including wells and related equipment” in the accompanying Consolidated Balance Sheets.
	During the nine months ended September 30, 2013, Athlon recorded non-cash equity-based compensation expense related to Class B interests of $1.3 million, which was allocated to lease operating expense and general and administrative expenses in the accompanying Consolidated Statements of Operations based on the allocation of the respective employees’ compensation.  During the nine months ended September 30, 2013, Athlon capitalized non-cash equity-based compensation expense related to Class B interests of $0.4 million as a component of “Evaluated, including wells and related equipment” in the accompanying Consolidated Balance Sheets.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies.	'
Commitments and Contingencies	'
	Note 12. Commitments and Contingencies
	From time to time, Athlon is a party to ongoing legal proceedings in the ordinary course of business, including workers’ compensation claims and employment-related disputes.  Management does not believe the results of these proceedings, individually or in the aggregate, will have a material adverse effect on Athlon’s business, financial position, results of operations, or liquidity.
	Additionally, Athlon has contractual obligations related to future plugging and abandonment expenses on oil and natural gas properties and related facilities disposal, long-term debt, commodity derivative contracts, operating leases, and development commitments.

Related_Party_Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2014
Related Party Transactions	'
Related Party Transactions	'
	Note 13. Related Party Transactions
	Services Agreement
	Athlon was a party to a Services Agreement which required it to compensate Apollo quarterly for consulting and advisory services, subject to certain quarterly and annual limits.  The Services Agreement also provided for reimbursement to Apollo for any reasonable out-of-pocket expenses incurred while performing services under the Services Agreement.  During the nine months ended September 30, 2013, Athlon incurred $0.5 million of advisory fees pursuant to the Services Agreement, which are included in “General and administrative expenses” in the accompanying Consolidated Statements of Operations.  Upon the consummation of the IPO, the Services Agreement was terminated and, in connection with the termination, Athlon paid $2.4 million to Apollo.  Such payment corresponded to the present value as of the date of termination of the aggregate annual fees that would have been payable during the remaining term of the Services Agreement.
	Exchange Agreement
	Upon the consummation of the IPO, Athlon entered into an exchange agreement (the “Exchange Agreement”) with its management team and certain employees who hold New Holdings Units.  Under the Exchange Agreement, each such holder (and certain permitted transferees thereof) may, under certain circumstances (subject to the terms of the exchange agreement), exchange their New Holdings Units for shares of Athlon’s common stock on a one-for-one basis (an “Exchange”), subject to customary conversion rate adjustments for stock splits, stock dividends, and reclassifications.  As a holder exchanges its New Holdings Units, Athlon’s interest in Holdings will be correspondingly increased.
	Tax Receivable Agreement
	Upon the consummation of the IPO, Athlon entered into a tax receivable agreement (the “TRA”) with its management team and certain employees who hold New Holdings Units (the “TRA Holders”) that provides for the payment from time to time by Athlon to such TRA Holders of 85% of the amount of the tax benefits, if any, that Athlon actually realizes as a result of increases in tax basis and certain other tax benefits related to exchanges of New Holdings Units pursuant to the Exchange Agreement, including tax benefits attributable to payments under the TRA.  These payment obligations are obligations of Athlon and not of Holdings.  For purposes of the TRA, the benefit deemed realized by Athlon will be computed by comparing its actual income tax liability (calculated with certain assumptions) to the amount of such taxes that Athlon would have been required to pay had there been no increase to the tax basis of Holdings’ assets as a result of the exchanges and had Athlon not entered into the TRA.  If Athlon elects to terminate the TRA early, it would be required to make an immediate payment equal to the net present value of the anticipated future tax benefits subject to the TRA (based upon certain assumptions and deemed events set forth in the TRA).  In addition, payments due under the TRA will be similarly accelerated following certain mergers, other changes of control, and early payments rights if exercised by the TRA Holders following an Exchange.
	On September 27, 2014, concurrently with the execution of the Merger Agreement, Athlon entered into a non-exchange agreement (the “Non-Exchange Agreement”) with the TRA Holders pursuant to which each TRA Holder shall be deemed to have exercised his or her rights under the Exchange Agreement and effected an Exchange in respect of all of his or her New Holdings Units immediately prior to the effective time of the Merger.  The Non-Exchange Agreement terminates automatically upon the termination of the Merger Agreement in accordance with its terms.
	Participation of Apollo Global in Debt and Equity Offerings
	Apollo Global received a portion of the gross spread as an initial purchaser of the 2022 Notes of $0.5 million.  Apollo Global was also an underwriter in Athlon’s April 2014 common stock offering and received a portion of the discounts and commissions paid to the underwriters of approximately $1.0 million.  Apollo Global received a portion of the gross spread as an initial purchaser of the 2021 Notes of $0.5 million.  Apollo Global was also an underwriter in the IPO and received a portion of the discounts and commissions paid to the underwriters of approximately $0.9 million.

Subsequent_Events

Subsequent Events	9 Months Ended
	Sep. 30, 2014
Subsequent Events	'
Subsequent Events	'
	Note 14. Subsequent Events
	In November 2014, lenders under the Credit Agreement completed their redetermination of the borrowing base resulting in an increase from $837.5 million to $1.0 billion.

Basis_of_Presentation_Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2014
Basis of Presentation	'
Consolidation	'
	Athlon’s consolidated financial statements include the accounts of its wholly owned and majority-owned subsidiaries.  All material intercompany balances and transactions have been eliminated in consolidation.
	In the opinion of management, the accompanying unaudited consolidated financial statements include all adjustments necessary to present fairly, in all material respects, Athlon’s financial position as of September 30, 2014, results of operations for the three and nine months ended September 30, 2014 and 2013, and cash flows for the nine months ended September 30, 2014 and 2013.  All adjustments are of a normal recurring nature.  These interim results are not necessarily indicative of results for an entire year.
	Certain amounts and disclosures have been condensed and omitted from the unaudited consolidated financial statements pursuant to the rules and regulations of the United States Securities and Exchange Commission.  Therefore, these unaudited consolidated financial statements should be read in conjunction with Athlon’s audited consolidated financial statements and related notes thereto included in Athlon’s 2013 Annual Report on Form 10-K.
Noncontrolling Interest	'
	Noncontrolling Interest
	As of September 30, 2014 and December 31, 2013, Athlon’s management team and certain employees owned approximately 1.9% and 2.2% of Holdings, respectively.  Holdings’ general partner, Athlon Holdings GP LLC, is a wholly owned subsidiary of Athlon.  Considering the presumption of control, Athlon has fully consolidated the financial position, results of operations, and cash flows of Holdings.
	As presented in the accompanying Consolidated Balance Sheets, “Noncontrolling interest” as of September 30, 2014 and December 31, 2013 of approximately $13.9 million and $10.8 million, respectively, represents Athlon’s management team and certain employees’ ownership of Holdings.  As presented in the accompanying Consolidated Statements of Operations, “Net income (loss) attributable to noncontrolling interest” of approximately $2.2 million and $3.1 million for the three and nine months ended September 30, 2014, respectively, and approximately $(0.2) million and $0.6 million for the three and nine months ended September 30, 2013, respectively, represents Holdings’ net income attributable to Athlon’s management team and certain employees.
	The following table summarizes the effects of changes in Athlon’s partnership interest in Holdings on Athlon’s equity for the periods indicated:
		Three months ended				Nine months ended
		September 30,				September 30,
		2014		2013		2014		2013
		(in thousands)
	Net income attributable to stockholders	$	72,693	$	2,482	$	99,361	$	37,058
	Transfer from noncontrolling interest:
	Increase in Athlon’s paid-in capital for deferred tax impact of change in noncontrolling interest due to issuance of common stock to the public	4,155		—		3,545		—
	Increase in Athlon’s paid-in capital for corporate reorganization	—		—		—		290,950
	Increase in Athlon’s paid-in capital for issuance of common stock to the public	63		295,473		570,612		295,473
	Net transfer from noncontrolling interest	4,218		295,473		574,157		586,423
	Change from net income attributable to stockholders and transfers from noncontrolling interest	$	76,911	$	297,955	$	673,518	$	623,481
New Accounting Pronouncements	'
	New Accounting Pronouncements
	In May 2014, the Financial Accounting Standards Board issued Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers”.  ASU 2014-09 supersedes most of the existing revenue recognition requirements in accounting principles generally accepted in the United States (“GAAP”) and requires (i) an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration the entity expects to be entitled to in exchange for those goods or services and (ii) requires expanded disclosures regarding the nature, amount, timing, and certainty of revenue and cash flows from contracts with customers.  ASU 2014-09 is effective retrospectively for annual and interim reporting periods beginning after December 15, 2016, with early application not permitted.  Athlon is evaluating the impact, if any, that the adoption of ASU 2014-09 will have on its financial position, results of operations, and liquidity.
	No other new accounting pronouncements issued or effective from January 1, 2014 through the date of this Report, had or are expected to have a material impact on Athlon’s unaudited consolidated financial statements.

Basis_of_Presentation_Tables

Basis of Presentation (Tables)	9 Months Ended
	Sep. 30, 2014
Basis of Presentation	'
Summary of effects of changes in Athlon's partnership interest in Holdings on Athlon's equity	'
		Three months ended				Nine months ended
		September 30,				September 30,
		2014		2013		2014		2013
		(in thousands)
	Net income attributable to stockholders	$	72,693	$	2,482	$	99,361	$	37,058
	Transfer from noncontrolling interest:
	Increase in Athlon’s paid-in capital for deferred tax impact of change in noncontrolling interest due to issuance of common stock to the public	4,155		—		3,545		—
	Increase in Athlon’s paid-in capital for corporate reorganization	—		—		—		290,950
	Increase in Athlon’s paid-in capital for issuance of common stock to the public	63		295,473		570,612		295,473
	Net transfer from noncontrolling interest	4,218		295,473		574,157		586,423
	Change from net income attributable to stockholders and transfers from noncontrolling interest	$	76,911	$	297,955	$	673,518	$	623,481

Acquisitions_Tables

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2014
Acquisitions	'
Schedule of estimated allocation of purchase price to the fair value of assets acquired and liabilities assumed	'
	Based on currently available information, the estimated allocation of the purchase price to the fair value of the assets acquired and liabilities assumed from Hibernia, Piedra, and Summit was as follows as of September 30, 2014:
		Hibernia		Piedra		Summit		Total
		(in thousands)
	Evaluated, including wells and related equipment	$	248,363	$	173,317	$	93,899	$	515,579
	Unevaluated	145,984		119,504		109,570		375,058
	Inventory	499		759		132		1,390
	Total assets acquired	394,846		293,580		203,601		892,027
	Other current liabilities	107		289		659		1,055
	Asset retirement obligations	706		536		437		1,679
	Total liabilities assumed	813		825		1,096		2,734
	Fair value of net assets acquired	$	394,033	$	292,755	$	202,505	$	889,293
Schedule of unaudited pro forma condensed financial data	'
		Three months ended September 30,				Nine months ended September 30,
		2014		2013		2014		2013
		(in thousands, except per share amounts)
	Pro forma total revenues	$	171,740	$	116,169	$	471,830	$	271,420
	Pro forma net income attributable to stockholders	$	75,259	$	4,398	$	111,592	$	38,197
	Pro forma net income per common share:
	Basic	$	0.76	$	0.05	$	1.14	$	0.45
	Diluted	$	0.76	$	0.05	$	1.14	$	0.45

Evaluated_Properties_Tables

Evaluated Properties (Tables)	9 Months Ended
	Sep. 30, 2014
Evaluated Properties	'
Schedule of evaluated, including wells and related equipment	'
		September 30,		December 31,
		2014		2013
		(in thousands)
	Evaluated leasehold costs	$	1,156,611	$	448,689
	Wells and related equipment - completed	1,314,766		748,900
	Wells and related equipment - in process	54,122		46,589
	Total evaluated	$	2,525,499	$	1,244,178

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Measurements	'
Summary of open commodity derivative contracts	'
	Period	Average		Weighted-			Net Asset Fair
		Daily		Average			Market Value
		Swap		Swap Price
		Volume
		(Bbl)		(per Bbl)			(in thousands)
	Q4 2014	10,961		$	92.31		$	2,168
	Q1 2015	12,800		92.12
	Q2 2015	12,800		92.12
	Q3 2015	11,800		93.69
	Q4 2015	11,800		93.69
	2015	12,296		92.88			22,727
	Q1 2016	2,500		92.35
	Q2 2016	2,500		92.35
	2016	1,243		92.35			2,718
							$	27,613
Schedule of committed 10% or greater (in terms of fair market value) of oil derivative contracts in asset positions from counterparties, or their affiliates	'
	At September 30, 2014, Athlon had committed 10% or greater (in terms of fair market value) of its oil derivative contracts in asset positions from the following counterparties:
		Fair Market Value of
		Oil Derivative
		Contracts
	Counterparty	Committed
		(in thousands)
	Citibank	$	7,524
	Barclays PLC	6,187
	Scotiabank	4,953
	J Aron	4,397
Schedule of fair value of derivative instruments not designated as hedging instruments	'
		Oil			Commodity			Total
	Balance Sheet	Commodity			Derivatives			Commodity
	Location	Derivatives			Netting (a)			Derivatives
		(in thousands)
	As of September 30, 2014
	Assets
	Derivatives - current	$	17,751		$	(803	)	$	16,948
	Derivatives - noncurrent	9,940			(613		)	9,327
	Total assets	27,691			(1,416		)	26,275
	Liabilities
	Derivatives - current	(803		)	803			—
	Derivatives - noncurrent	(613		)	613			—
	Total liabilities	(1,416		)	1,416			—
	Net asset	$	26,275		$	—		$	26,275
	As of December 31, 2013
	Assets
	Derivatives - current	$	143		$	(143	)	$	—
	Derivatives - noncurrent	2,330			—			2,330
	Total assets	2,473			(143		)	2,330
	Liabilities
	Derivatives - current	(8,497		)	143			(8,354		)
	Derivatives - noncurrent	—			—			—
	Total liabilities	(8,497		)	143			(8,354		)
	Net liability	$	(6,024	)	$	—		$	(6,024	)
	(a)     Represents counterparty netting under ISDA Agreements, which allow for netting of commodity derivative contracts.  These derivative instruments are reflected net on the accompanying Consolidated Balance Sheets.
Schedule of effect of derivative instruments not designated as hedges on accompanying consolidated statements of operation	'
				Amount of Loss (Gain) Recognized in Income
		Location of Loss (Gain)		Three months ended September 30,						Nine months ended September 30,
	Derivatives Not Designated as Hedges	Recognized in Income		2014			2013			2014			2013
				(in thousands)
	Commodity derivative contracts	Derivative fair value loss (gain)		$	(58,526	)	$	27,037		$	(14,949	)	$	21,331
Schedule of assets and liabilities that were accounted for at fair value on a recurring basis	'
					Fair Value Measurements at Reporting Date Using
					Quoted Prices in
					Active Markets for			Significant Other			Significant
					Identical Assets			Observable Inputs			Unobservable Inputs
	Description	Net Asset/(Liability)			(Level 1)			(Level 2)			(Level 3)
		(in thousands)
	As of September 30, 2014
	Oil derivative contracts - swaps	$	27,613		$	—		$	27,613		$	—
	Oil derivative contracts - basis differential swaps	(1,338		)	—			(1,338		)	—
	Total	$	26,275		$	—		$	26,275		$	—
	As of December 31, 2013
	Oil derivative contracts - swaps	$	(6,024	)	$	—		$	(6,024	)	$	—

Asset_Retirement_Obligations_T

Asset Retirement Obligations (Tables)	9 Months Ended
	Sep. 30, 2014
Asset Retirement Obligations	'
Summary of changes in asset retirement obligations	'
	The following table summarizes the changes in Athlon’s asset retirement obligations for the nine months ended September 30, 2014 (in thousands):
	Balance at January 1	$	6,855
	Liabilities assumed in acquisitions	3,140
	Liabilities incurred from new wells	1,463
	Liabilities settled	(103		)
	Accretion of discount	690
	Revisions of previous estimates	292
	Balance at September 30	12,337
	Less: current portion	9
	Asset retirement obligations - long-term	$	12,328

LongTerm_Debt_Tables

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2014
Long-Term Debt.	'
Schedule of long-term debt maturities	'
		Maturity		September 30,			December 31,
		Date		2014			2013
				(in thousands)
	Credit agreement	3/19/18		$	236,000		$	—
	73/8% senior notes	4/15/21		500,000			500,000
	6% senior notes	5/1/22		650,000			—
	Total			$	1,386,000		$	500,000
Schedule of quarterly commitment fee on unused portion of the Credit Agreement and applicable margin for Eurodollar and base rate loans	'
	Ratio of Outstanding Borrowings to Borrowing Base	Unused		Applicable		Applicable
		Commitment Fee		Margin for		Margin for Base
				Eurodollar Loans		Rate Loans
	Less than or equal to .30 to 1	0.375	%	1.5	%	0.5	%
	Greater than .30 to 1 but less than or equal to .60 to 1	0.375	%	1.75	%	0.75	%
	Greater than .60 to 1 but less than or equal to .80 to 1	0.5	%	2	%	1	%
	Greater than .80 to 1 but less than or equal to .90 to 1	0.5	%	2.25	%	1.25	%
	Greater than .90 to 1	0.5	%	2.5	%	1.5	%

Income_Taxes_Tables

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2014
Income Taxes	'
Schedule of the components of income tax provision	'
		Nine months ended
		September 30,
		2014			2013
		(in thousands)
	Federal:
	Current	$	869		$	—
	Deferred	54,992			6,202
	Total federal	55,861			6,202
	State, net of federal benefit:
	Deferred	2,055			603
	Total state	2,055			603
	Income tax provision	$	57,916		$	6,805
Schedule of reconciliation of income tax provision with income tax at the Federal statutory rate	'
		Nine months ended September 30,
		2014			2013
		(in thousands)
	Income before income taxes	$	160,424		$	44,479
	Less: net income prior to corporate reorganization	—			(26,780		)
	Less: net income attributable to noncontrolling interest	(3,147		)	(616		)
	Income before income taxes and noncontrolling interest subsequent to corporate reorganization	$	157,277		$	17,083
	Income taxes at the Federal statutory rate	$	55,047		$	5,979
	State income taxes, net of federal benefit	2,055			603
	Provision to return adjustment	191			59
	Permanent and other	623			164
	Income tax provision	$	57,916		$	6,805

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share	'
Schedule of allocation of net income attributable to common stockholders and EPS computations	'
		Three months ended September 30,						Nine months ended September 30,
		2014			2013			2014			2013
		(in thousands, except per share amounts)
	Basic EPS
	Numerator:
	Undistributed net income attributable to stockholders	$	72,693		$	2,482		$	99,361		$	37,058
	Participation rights of unvested stock awards in undistributed earnings	(1,135		)	(6		)	(1,147		)	(6		)
	Basic undistributed net income attributable to stockholders	$	71,558		$	2,476		$	98,214		$	37,052
	Denominator:
	Basic weighted average shares outstanding	97,064			76,637			90,904			69,810
	Basic EPS attributable to stockholders	$	0.74		$	0.03		$	1.08		$	0.53
	Diluted EPS
	Numerator:
	Undistributed net income attributable to stockholders	$	72,693		$	2,482		$	99,361		$	37,058
	Participation rights of unvested stock awards in undistributed earnings	(1,135		)	(6		)	(1,147		)	(6		)
	Effect of conversion of New Holdings Units to shares of Athlon’s common stock (a)	—			(215		)	—			616
	Diluted undistributed net income attributable to stockholders	$	71,558		$	2,261		$	98,214		$	37,668
	Denominator:
	Basic weighted average shares outstanding	97,064			76,637			90,904			69,810
	Effect of conversion of New Holdings Units to shares of Athlon’s common stock (a)	—			1,856			—			1,856
	Diluted weighted average shares outstanding	97,064			78,493			90,904			71,666
	Diluted EPS attributable to stockholders	$	0.74		$	0.03		$	1.08		$	0.53
	(a)     For the three and nine months ended September 30, 2014, 1,855,563 New Holdings Units were outstanding but excluded from the EPS calculations because their effect would have been antidilutive.

Incentive_Stock_Plans_Tables

Incentive Stock Plans (Tables)	9 Months Ended
	Sep. 30, 2014
Incentive Stock Plans	'
Summary of changes in unvested stock awards	'
				Weighted -
				Average
		Number of		Grant Date
		Shares		Fair Value
	Outstanding at January 1	638,913		$	34.88
	Granted	1,317,907		45.03
	Vested	(209,540	)	37.8
	Forfeited	(13,114	)	32.01
	Outstanding at September 30	1,734,166		42.27

Formation_of_the_Company_and_D1

Formation of the Company and Description of Business (Details) (USD $)	0 Months Ended						0 Months Ended	9 Months Ended
In Millions, except Share data, unless otherwise specified	Apr. 23, 2014	Aug. 07, 2013	Apr. 30, 2013	Sep. 30, 2014	Dec. 31, 2013	Sep. 27, 2014	Aug. 07, 2013	Sep. 30, 2014
						Encana	Holdings	Holdings
							Class A limited partners	Class A limited partners
Formation of Company and Description of Business	'	'	'	'	'	'	'	'
Shares of common stock issued	14,806,250	15,789,474	'	'	'	'	'	'
Per share price (in dollars per share)	$40	$20	'	'	'	$58.50	'	'
Net proceeds from IPO, after deducting underwriting discounts and commissions and offering expenses (in dollars)	'	$295.70	'	'	'	'	'	'
Total number of New Holdings Units exchangeable for common stock (in shares)	'	'	'	'	'	'	1,855,563	'
Number of common stock exchangeable against each New Holdings Unit (in shares)	'	'	1	'	'	'	'	1
Common stock, par value (in dollars per share)	'	'	'	$0.01	$0.01	$0.01	'	'

Basis_of_Presentation_Details

Basis of Presentation (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Apr. 23, 2014	Dec. 31, 2013
Noncontrolling interest	'	'	'	'	'	'
Percentage of ownership interest of entity's management team and certain employees	1.90%	'	1.90%	'	2.20%	'
Noncontrolling interest	$13,935	'	$13,935	'	'	$10,788
Net income (loss) attributable to noncontrolling interest	2,205	-215	3,147	616	'	'
Effects of changes in Athlon's partnership interest in Holdings on Athlon's equity	'	'	'	'	'	'
Net income attributable to stockholders	72,693	2,482	99,361	37,058	'	'
Transfer from noncontrolling interest:	'	'	'	'	'	'
Increase in Athlon's paid-in capital for deferred tax impact of change in noncontrolling interest due to issuance of common stock to the public	4,155	'	3,545	'	'	'
Increase in Athlon's paid-in capital for corporate reorganization	'	'	'	290,950	'	'
Increase in Athlon's paid-in capital for issuance of common stock to the public	63	295,473	570,612	295,473	'	'
Net transfer from noncontrolling interest	4,218	295,473	574,157	586,423	'	'
Change from net income attributable to stockholders and transfers from noncontrolling interest	$76,911	$297,955	$673,518	$623,481	'	'
Holdings | Class A limited partners	'	'	'	'	'	'
Noncontrolling interest	'	'	'	'	'	'
Percentage of ownership interest of entity's management team and certain employees	1.90%	'	1.90%	'	'	2.20%

Acquisitions_Details

Acquisitions (Details) (USD $)

3 Months Ended

9 Months Ended

0 Months Ended

4 Months Ended

0 Months Ended

4 Months Ended

0 Months Ended

1 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Jun. 02, 2014

Sep. 30, 2014

Jun. 03, 2014

Sep. 30, 2014

Jun. 03, 2014

Aug. 28, 2014

Sep. 30, 2014

Aug. 28, 2014

Hibernia

Hibernia

Piedra

Piedra

Piedra

Summit

Summit

Summit

Acquisitions

'

'

'

'

'

'

'

'

'

'

'

'

Cash paid for acquisition

'

'

'

'

$394,000,000

'

$292,800,000

'

'

$202,500,000

'

'

Revenues

166,041,000

88,425,000

408,220,000

208,336,000

'

30,300,000

'

12,400,000

'

'

2,400,000

'

Direct operating expenses

36,015,000

74,215,000

212,650,000

137,292,000

'

3,500,000

'

1,800,000

'

'

500,000

'

Transaction costs incurred

'

'

'

'

700,000

'

'

'

600,000

'

'

100,000

Allocation of the purchase price to the fair value of the assets acquired and liabilities assumed

'

'

'

'

'

'

'

'

'

'

'

'

Evaluated, including wells and related equipment

515,579,000

'

515,579,000

'

'

248,363,000

'

173,317,000

'

'

93,899,000

'

Unevaluated

375,058,000

'

375,058,000

'

'

145,984,000

'

119,504,000

'

'

109,570,000

'

Inventory

1,390,000

'

1,390,000

'

'

499,000

'

759,000

'

'

132,000

'

Total assets acquired

892,027,000

'

892,027,000

'

'

394,846,000

'

293,580,000

'

'

203,601,000

'

Other current liabilities

1,055,000

'

1,055,000

'

'

107,000

'

289,000

'

'

659,000

'

Asset retirement obligations

1,679,000

'

1,679,000

'

'

706,000

'

536,000

'

'

437,000

'

Total liabilities assumed

2,734,000

'

2,734,000

'

'

813,000

'

825,000

'

'

1,096,000

'

Fair value of net assets acquired

889,293,000

'

889,293,000

'

'

394,033,000

'

292,755,000

'

'

202,505,000

'

Unaudited pro forma condensed financial data

'

'

'

'

'

'

'

'

'

'

'

'

Pro forma total revenues

171,740,000

116,169,000

471,830,000

271,420,000

'

'

'

'

'

'

'

'

Pro forma net income attributable to stockholders

$75,259,000

$4,398,000

$111,592,000

$38,197,000

'

'

'

'

'

'

'

'

Pro forma net income per common share:

'

'

'

'

'

'

'

'

'

'

'

'

Basic (in dollar per share)

$0.76

$0.05

$1.14

$0.45

'

'

'

'

'

'

'

'

Diluted (in dollar per share)

$0.76

$0.05

$1.14

$0.45

'

'

'

'

'

'

'

'

Evaluated_Properties_Details

Evaluated Properties (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Evaluated, including wells and related equipment	'	'
Evaluated leasehold costs	$1,156,611	$448,689
Wells and related equipment - completed	1,314,766	748,900
Wells and related equipment - in process	54,122	46,589
Total evaluated	$2,525,499	$1,244,178

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Apr. 30, 2013	Sep. 30, 2014	1-May-14	Sep. 30, 2014	Sep. 30, 2014
In Millions, unless otherwise specified	2021 Notes	2021 Notes	2021 Notes	2022 Notes	2022 Notes	Level 1 input	Level 1 input
						2021 Notes	2022 Notes
Fair value measurements	'	'	'	'	'	'	'
Interest rate (as a percent)	7.38%	7.38%	7.38%	6.00%	6.00%	7.38%	6.00%
Senior notes	'	'	'	'	'	$542.50	$698.80

Fair_Value_Measurements_Detail1

Fair Value Measurements (Details 2) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Open commodity derivative contracts	'	'
Summary of open commodity derivative contracts	'	'
Net Assets Fair Market Value	$27,613	($6,024)
Open commodity derivative contracts | Q4 2014	'	'
Summary of open commodity derivative contracts	'	'
Net Assets Fair Market Value	2,168	'
Open commodity derivative contracts | 2015	'	'
Summary of open commodity derivative contracts	'	'
Net Assets Fair Market Value	22,727	'
Open commodity derivative contracts | 2016	'	'
Summary of open commodity derivative contracts	'	'
Net Assets Fair Market Value	2,718	'
Commodity derivative contracts with swap price | Q4 2014	'	'
Summary of open commodity derivative contracts	'	'
Average Daily Swap Volume	10,961	'
Weighted-Average Swap Price	92.31	'
Commodity derivative contracts with swap price | Q1 2015	'	'
Summary of open commodity derivative contracts	'	'
Average Daily Swap Volume	12,800	'
Weighted-Average Swap Price	92.12	'
Commodity derivative contracts with swap price | Q2 2015	'	'
Summary of open commodity derivative contracts	'	'
Average Daily Swap Volume	12,800	'
Weighted-Average Swap Price	92.12	'
Commodity derivative contracts with swap price | Q3 2015	'	'
Summary of open commodity derivative contracts	'	'
Average Daily Swap Volume	11,800	'
Weighted-Average Swap Price	93.69	'
Commodity derivative contracts with swap price | Q4 2015	'	'
Summary of open commodity derivative contracts	'	'
Average Daily Swap Volume	11,800	'
Weighted-Average Swap Price	93.69	'
Commodity derivative contracts with swap price | 2015	'	'
Summary of open commodity derivative contracts	'	'
Average Daily Swap Volume	12,296	'
Weighted-Average Swap Price	92.88	'
Commodity derivative contracts with swap price | Q1 2016	'	'
Summary of open commodity derivative contracts	'	'
Average Daily Swap Volume	2,500	'
Weighted-Average Swap Price	92.35	'
Commodity derivative contracts with swap price | Q2 2016	'	'
Summary of open commodity derivative contracts	'	'
Average Daily Swap Volume	2,500	'
Weighted-Average Swap Price	92.35	'
Commodity derivative contracts with swap price | 2016	'	'
Summary of open commodity derivative contracts	'	'
Average Daily Swap Volume	1,243	'
Weighted-Average Swap Price	92.35	'
Midland-Cushing basis differential swaps | 2015	'	'
Summary of open commodity derivative contracts	'	'
Average Daily Swap Volume	6,000	'
Weighted-Average Swap Price	5.19	'
Net Assets Fair Market Value	$1,300	'

Fair_Value_Measurements_Detail2

Fair Value Measurements (Details 3) (ISDA agreements, USD $)	Sep. 30, 2014
In Thousands, unless otherwise specified
Citibank	'
Counterparty risk	'
Fair Market Value of Oil Derivative Contracts Committed	$7,524
Barclays PLC	'
Counterparty risk	'
Fair Market Value of Oil Derivative Contracts Committed	6,187
Scotiabank	'
Counterparty risk	'
Fair Market Value of Oil Derivative Contracts Committed	4,953
J Aron	'
Counterparty risk	'
Fair Market Value of Oil Derivative Contracts Committed	$4,397

Fair_Value_Measurements_Detail3

Fair Value Measurements (Details 4) (Commodity contracts, USD $)	Sep. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Liabilities	'	'
Net assets (liabilities)	$27,613	($6,024)
Derivative instruments not designated as hedging instruments | Oil	'	'
Assets	'	'
Oil Commodity Derivatives, assets	27,691	2,473
Commodity Derivatives Netting, assets	-1,416	-143
Total Commodity Derivatives	26,275	2,330
Liabilities	'	'
Oil Commodity Derivatives, liabilities	-1,416	-8,497
Commodity Derivatives Netting, liabilities	1,416	143
Total Commodity Derivatives	'	-8,354
Net assets (liabilities)	26,275	-6,024
Derivative instruments not designated as hedging instruments | Oil | Derivative assets - current	'	'
Assets	'	'
Oil Commodity Derivatives, assets	17,751	143
Commodity Derivatives Netting, assets	-803	-143
Total Commodity Derivatives	16,948	'
Derivative instruments not designated as hedging instruments | Oil | Derivative assets - noncurrent	'	'
Assets	'	'
Oil Commodity Derivatives, assets	9,940	2,330
Commodity Derivatives Netting, assets	-613	'
Total Commodity Derivatives	9,327	2,330
Derivative instruments not designated as hedging instruments | Oil | Derivative liabilities - current	'	'
Liabilities	'	'
Oil Commodity Derivatives, liabilities	-803	-8,497
Commodity Derivatives Netting, liabilities	803	143
Total Commodity Derivatives	'	-8,354
Derivative instruments not designated as hedging instruments | Oil | Derivative liabilities - noncurrent	'	'
Liabilities	'	'
Oil Commodity Derivatives, liabilities	-613	'
Commodity Derivatives Netting, liabilities	$613	'

Fair_Value_Measurements_Detail4

Fair Value Measurements (Details 5) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair value measurements	'	'	'	'
Amount of Loss (gain) Recognized in Income	($58,526)	$27,037	($14,949)	$21,331
Derivative instruments not designated as hedges | Commodity contracts | Derivative fair value loss (gain)	'	'	'	'
Fair value measurements	'	'	'	'
Amount of Loss (gain) Recognized in Income	($58,526)	$27,037	($14,949)	$21,331

Fair_Value_Measurements_Detail5

Fair Value Measurements (Details 6) (Commodity contracts, USD $)	Sep. 30, 2014	Dec. 31, 2013
Fair Value Hierarchy	'	'
Decrease in net commodity derivative asset and liabilities	$56,000	$39,000
Recurring | Net Asset/(Liability)	'	'
Fair Value Hierarchy	'	'
Total	26,275,000	'
Recurring | Net Asset/(Liability) | Oil | Swaps	'	'
Fair Value Hierarchy	'	'
Total	27,613,000	-6,024,000
Recurring | Net Asset/(Liability) | Oil | Basis differential swaps	'	'
Fair Value Hierarchy	'	'
Total	-1,338,000	'
Recurring | Significant Other Observable Inputs (Level 2)	'	'
Fair Value Hierarchy	'	'
Total	26,275,000	'
Recurring | Significant Other Observable Inputs (Level 2) | Oil | Swaps	'	'
Fair Value Hierarchy	'	'
Total	27,613,000	-6,024,000
Recurring | Significant Other Observable Inputs (Level 2) | Oil | Basis differential swaps	'	'
Fair Value Hierarchy	'	'
Total	($1,338,000)	'

Asset_Retirement_Obligations_D

Asset Retirement Obligations (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Asset retirement obligations	'	'	'	'	'
Balance at the beginning of the period	'	'	$6,855	'	'
Liabilities assumed in acquisitions	'	'	3,140	'	'
Liabilities incurred from new wells	'	'	1,463	'	'
Liabilities settled	'	'	-103	'	'
Accretion of discount	273	174	690	485	'
Revisions of previous estimates	'	'	292	'	'
Balance at the end of the period	12,337	'	12,337	'	'
Less: current portion	9	'	9	'	'
Asset retirement obligations - long-term	$12,328	'	$12,328	'	$6,795

LongTerm_Debt_Details

Long-Term Debt (Details) (USD $)

9 Months Ended

9 Months Ended

0 Months Ended

0 Months Ended

Sep. 30, 2014

Mar. 19, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Dec. 31, 2013

Apr. 30, 2013

Apr. 30, 2014

Apr. 30, 2014

Apr. 30, 2014

Apr. 30, 2014

2-May-14

Sep. 30, 2014

1-May-14

2-May-14

2-May-14

2-May-14

2-May-14

2-May-14

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Credit agreement

Senior notes

2021 Notes

2021 Notes

2021 Notes

2021 Notes

2021 Notes

2021 Notes

2021 Notes

2022 Notes

2022 Notes

2022 Notes

2022 Notes

2022 Notes

2022 Notes

2022 Notes

2022 Notes

Applicable Margin for Eurodollar Loans

Applicable Margin for Eurodollar Loans

Applicable Margin for Base Rate Loans

Applicable Margin for Base Rate Loans

Applicable Margin for Base Rate Loans

Applicable Margin for Base Rate Loans

Applicable Margin for Base Rate Loans

Less than or equal to .30 to 1

Less than or equal to .30 to 1

Less than or equal to .30 to 1

Greater than .30 to 1 but less than or equal to .60 to 1

Greater than .30 to 1 but less than or equal to .60 to 1

Greater than .30 to 1 but less than or equal to .60 to 1

Greater than .60 to 1 but less than or equal to .80 to 1

Greater than .60 to 1 but less than or equal to .80 to 1

Greater than .60 to 1 but less than or equal to .80 to 1

Greater than .80 to 1 but less than or equal to .90 to 1

Greater than .80 to 1 but less than or equal to .90 to 1

Greater than .80 to 1 but less than or equal to .90 to 1

Greater than .90 to 1

Greater than .90 to 1

Greater than .90 to 1

Maximum

Maximum

Maximum

Maximum

Minimum

Minimum

Minimum

Minimum

Maximum

Upon assets disposition triggering events

Prior to April 15, 2016

Prior to April 15, 2016

Maximum

Prior to May 1, 2017

Prior to May 1, 2017

On or prior to July 15, 2015

On or prior to July 15, 2015

Maximum

Eurodollar rate

LIBOR

Eurodollar rate

LIBOR

Base Rate

Prime rate

Federal funds rate

Applicable Margin for Eurodollar Loans

Applicable Margin for Base Rate Loans

Applicable Margin for Eurodollar Loans

Applicable Margin for Base Rate Loans

Applicable Margin for Eurodollar Loans

Applicable Margin for Base Rate Loans

Applicable Margin for Eurodollar Loans

Applicable Margin for Base Rate Loans

Applicable Margin for Eurodollar Loans

Applicable Margin for Base Rate Loans

Less than or equal to .30 to 1

Greater than .30 to 1 but less than or equal to .60 to 1

Greater than .60 to 1 but less than or equal to .80 to 1

Greater than .80 to 1 but less than or equal to .90 to 1

Greater than .30 to 1 but less than or equal to .60 to 1

Greater than .60 to 1 but less than or equal to .80 to 1

Greater than .80 to 1 but less than or equal to .90 to 1

Greater than .90 to 1

Redemption from proceeds of certain equity offerings

Prior to April 15, 2016

Redemption from proceeds of certain equity offerings

Redemption of debt instrument upon change of control

Upon assets disposition triggering events

Prior to May 1, 2017

Redemption from proceeds of certain equity offerings

Redemption from proceeds of certain equity offerings

Long-term debt

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate principal amount of notes issued

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$500,000,000

$500,000,000

$500,000,000

'

'

'

'

'

$650,000,000

$650,000,000

'

'

'

'

'

Interest rate (as a percent)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

7.38%

7.38%

7.38%

'

'

'

'

'

6.00%

6.00%

'

'

'

'

'

Percentage of aggregate principal amount of notes that can be redeemed

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

35.00%

'

'

'

'

'

'

'

35.00%

Redemption price of debt instrument (as a percent)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

101.00%

100.00%

107.38%

'

'

'

'

100.00%

106.00%

110.00%

101.00%

'

Net proceeds from the issuance of senior notes due 2022

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

639,100,000

'

'

'

'

'

'

'

Fixed charge coverage ratio

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Maximum amount committed by lender

'

1,000,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Current borrowing base

837,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding borrowings

236,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Remaining borrowing base

601,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding letters of credit

$0

'

'

'

'

'

'

'

'

'

'

'

'

'

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'

'

'

'

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'

'

'

'

'

'

'

Ratio of Outstanding Borrowings to Borrowing Base

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.3

0.6

0.8

0.9

0.3

0.6

0.8

0.9

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unused Commitment Fee (as a percent)

'

'

'

'

'

'

'

'

'

0.38%

'

'

0.38%

'

'

0.50%

'

'

0.50%

'

'

0.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Applicable Margin (as a percent)

'

'

'

'

1.00%

'

'

'

0.50%

'

1.50%

0.50%

'

1.75%

0.75%

'

2.00%

1.00%

'

2.25%

1.25%

'

2.50%

1.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Variable interest rate base

'

'

'Eurodollar rate

'LIBOR

'Eurodollar rate

'LIBOR

'Base Rate

'prime rate

'Federal fund

'

'

'

'

'

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'

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'

'

'

'

'

'

'

'

Ratio of consolidated total debt to EBITDAX

4.5

'

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'

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'

'

'

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'

'

'

'

'

'

'

Maximum projected production that can be hedged (as a percent)

85.00%

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'

'

Period over which hedging limitation requirement of the projected production from proved reserve is required to be maintained

'66 months

'

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'

'

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	0 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Apr. 23, 2014	Aug. 07, 2013	Sep. 30, 2014	Sep. 30, 2013
Stockholders' Equity	'	'	'	'
Shares of common stock issued	14,806,250	15,789,474	'	'
Per share price (in dollars per share)	$40	$20	'	'
Net proceeds from public offering, after deducting underwriting discounts and commissions and offering expenses (in dollars)	$570,800	'	$570,760	$296,044
Percentage of ownership noncontrolling interest	2.20%	'	1.90%	'

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Federal:	'	'	'	'
Current	'	'	$869	'
Deferred	'	'	54,992	6,202
Total federal	'	'	55,861	6,202
State, net of federal benefit:	'	'	'	'
Deferred	'	'	2,055	603
Total state	'	'	2,055	603
Income tax provision	42,662	1,934	57,916	6,805
Reconciliation of income tax provision with income tax at the Federal statutory rate	'	'	'	'
Income before income taxes	117,560	4,201	160,424	44,479
Less: net income prior to corporate reorganization	'	'	'	-26,780
Less: net income attributable to noncontrolling interest	-2,205	215	-3,147	-616
Income before income taxes and noncontrolling interest subsequent to corporate reorganization	'	'	157,277	17,083
Income taxes at the Federal statutory rate	'	'	55,047	5,979
State income taxes, net of federal benefit	'	'	2,055	603
Provision to return adjustment	'	'	191	59
Permanent and other	'	'	623	164
Income tax provision	$42,662	$1,934	$57,916	$6,805

Earnings_Per_Share_Details

Earnings Per Share (Details) (USD $)	0 Months Ended		3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Aug. 07, 2013	Apr. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Apr. 23, 2014
Earnings Per Share	'	'	'	'	'	'	'
Outstanding common stock prior to consummation of IPO (in shares)	'	960,907	'	'	'	'	'
Issue price of IPO (in dollars per share)	$20	'	'	'	'	'	$40
Stock split ratio	65.266	'	'	'	'	'	'
Outstanding common stock shares prior to closing of IPO	66,339,615	'	'	'	'	'	'
Conversion of units into common stock (in units)	'	1	'	'	'	'	'
Numerator:	'	'	'	'	'	'	'
Undistributed net income attributable to stockholders	'	'	$72,693	$2,482	$99,361	$37,058	'
Participation rights of unvested stock awards in undistributed earnings	'	'	-1,135	-6	-1,147	-6	'
Basic undistributed net income attributable to stockholders	'	'	71,558	2,476	98,214	37,052	'
Denominator:	'	'	'	'	'	'	'
Basic weighted average shares outstanding	'	'	97,064,000	76,637,000	90,904,000	69,810,000	'
Basic EPS attributable to stockholders (in dollars per share)	'	'	$0.74	$0.03	$1.08	$0.53	'
Numerator:	'	'	'	'	'	'	'
Undistributed net income attributable to stockholders	'	'	72,693	2,482	99,361	37,058	'
Participation rights of unvested stock awards in undistributed earnings	'	'	-1,135	-6	-1,147	-6	'
Effect of conversion of New Holdings Units to shares of Athlon's common stock	'	'	'	-215	'	616	'
Diluted undistributed net income attributable to stockholders	'	'	$71,558	$2,261	$98,214	$37,668	'
Denominator:	'	'	'	'	'	'	'
Basic weighted average shares outstanding	'	'	97,064,000	76,637,000	90,904,000	69,810,000	'
Effect of conversion of New Holdings Units to shares of Athlon's common stock	'	'	'	1,856,000	'	1,856,000	'
Diluted weighted average shares outstanding	'	'	97,064,000	78,493,000	90,904,000	71,666,000	'
Diluted EPS attributable to stockholders (in dollars per share)	'	'	$0.74	$0.03	$1.08	$0.53	'
Antidilutive New Holdings Units excluded from EPS calculations (in shares)	'	'	1,855,563	'	1,855,563	'	'

Incentive_Stock_Plans_Details

Incentive Stock Plans (Details) (USD $)

9 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Aug. 07, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Aug. 01, 2013

Sep. 30, 2014

2013 Incentive Award Plan

2013 Incentive Award Plan

2013 Incentive Award Plan

2013 Incentive Award Plan

2013 Incentive Award Plan

2013 Incentive Award Plan

Maximum

Maximum

Holdings

Holdings

Stock Awards

Stock Awards

Stock Awards

2013 Incentive Award Plan

2013 Incentive Award Plan

Class B limited partners

Class B limited partners

Vesting of awards subject to time and continued employment

Vesting of awards subject to time, continued employment and performance condition

Non-employee directors

Incentive stock plans

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate shares of common stock available for issuance under the 2013 stock incentive plan

'

'

11,759,386

'

8,400,000

'

'

'

'

'

'

'

Aggregate shares of common stock available for issuance under the 2013 stock incentive plan at January 1, 2014 under first condition

'

'

'

'

'

'

'

'

12,000,000

'

'

'

Percentage increase to shares of common stock available for issuance under the 2013 stock incentive plan at January 1, 2014 under second condition

'

'

'

'

'

'

'

'

4.00%

'

'

'

Grant date fair value of awards

'

'

'

'

'

'

'

'

'

$700,000

'

'

Remaining shares available for grant

'

'

9,815,681

'

'

'

'

'

'

'

'

'

Non-cash equity-based compensation expense

16,006,000

1,799,000

16,000,000

500,000

'

'

'

'

'

'

1,200,000

1,300,000

Capitalized non-cash equity-based compensation expense

'

'

1,700,000

37,000

'

'

'

'

'

'

400,000

400,000

Vesting period of stock awards

'

'

'

'

'

'3 years

'

'

'

'

'

'

Unvested stock awards

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding at beginning of the period (in shares)

'

'

'

'

'

638,913

'

'

'

'

'

'

Vested (in shares)

'

'

'

'

'

-209,540

'

'

'

'

'

'

Forfeited (in shares)

'

'

'

'

'

-13,114

'

'

'

'

'

'

Outstanding at end of the period (in shares)

'

'

'

'

'

1,734,166

1,139,907

594,259

'

'

'

'

Weighted - Average Grant Date Fair Value

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding at beginning of period (in dollars per share)

'

'

'

'

'

$34.88

'

'

'

'

'

'

Granted (in dollars per share)

'

'

'

'

'

$45.03

'

'

'

'

'

'

Vested (in dollars per share)

'

'

'

'

'

$37.80

'

'

'

'

'

'

Forfeited (in dollars per share)

'

'

'

'

'

$32.01

'

'

'

'

'

'

Outstanding at end of the period (in dollars per share)

'

'

'

'

'

$42.27

'

'

'

'

'

'

Additional disclosure

'

'

'

'

'

'

'

'

'

'

'

'

Granted (in shares)

'

'

'

'

'

1,317,907

872,444

442,592

'

'

'

'

Unvested stock awards outstanding (in shares)

'

'

'

'

'

1,734,166

1,139,907

594,259

'

'

'

'

Number of stock awards vested

'

'

'

'

'

209,540

'

'

'

'

'

'

Vested stock awards from which shares were withheld to satisfy employee's tax withholding obligations

'

'

'

'

'

285,373

'

'

'

'

'

'

Number of shares of common stock withheld to satisfy employees' minimum tax withholding obligations

'

'

'

'

'

86,266

'

'

'

'

'

'

Total fair value of stock awards vested

'

'

'

'

'

12,700,000

'

'

'

'

'

'

Unvested stock awards subject to variable accounting (in shares)

'

'

'

'

'

0

'

'

'

'

'

'

Total unrecognized compensation cost related to unvested stock awards

'

'

'

'

'

$53,900,000

'

'

'

'

'

'

Weighted-average period for recognition of unrecognized compensation cost

'

'

'

'

'

'2 years 8 months 12 days

'

'

'

'

'

'

Related_Party_Transactions_Det

Related Party Transactions (Details) (USD $)	0 Months Ended	9 Months Ended	0 Months Ended	9 Months Ended		0 Months Ended	1 Months Ended		0 Months Ended
In Millions, except Share data, unless otherwise specified	Apr. 30, 2013	Sep. 30, 2014	Aug. 07, 2014	Sep. 30, 2014	Sep. 30, 2014	Aug. 07, 2013	Apr. 30, 2014	31-May-14	Apr. 30, 2013
			Apollo	Apollo	Management team and certain employees	Apollo Global	Apollo Global	Apollo Global	Apollo Global
								2022 Notes	2021 Notes
Related party transactions	'	'	'	'	'	'	'	'	'
Advisory fees pursuant to the Services Agreement	'	'	$0.50	'	'	'	'	'	'
Number of common stock exchangeable against each New Holdings Unit	1	'	'	'	1	'	'	'	'
Percentage of income tax benefits distributable to holders of New Holdings Units	'	85.00%	'	'	'	'	'	'	'
Payment of termination costs to related parties	'	'	'	2.4	'	'	'	'	'
Portion of the gross spread received as an initial purchaser of notes issued	'	'	'	'	'	'	'	0.5	0.5
Payment of discounts and commissions to underwriters	'	'	'	'	'	$0.90	$1	'	'

Subsequent_Events_Details

Subsequent Events (Details) (Credit agreement, USD $)	Sep. 30, 2014	Nov. 30, 2014
In Millions, unless otherwise specified		Subsequent event
Subsequent events	'	'
Current borrowing base	$837.50	$1,000