Antero Midstream (AM) 10-Q 31 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 26, 2018
Document and Entity Information
Entity Registrant Name	Antero Midstream GP LP
Entity Central Index Key	1,623,925
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		186,219,438
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash	$ 4,246	$ 5,987
Prepaid expenses	56
Deferred financing costs	140
Total current assets	4,442	5,987
Investment in Antero Midstream Partners LP	37,816	23,772
Total assets	42,258	29,759
Current liabilities:
Accounts payable and accrued liabilities	939	293
Income taxes payable	13,223	13,858
Total current liabilities	14,162	14,151
Non-current liabilities:
Liability for equity-based compensation	2,970
Total liabilities	17,132	14,151
Partners' capital:
Common shareholders - public (186,181, 975 shares and 186,199,995 shares issued and outstanding at December 31, 2017 and September 30, 2018, respectively)	(10,163)	(19,866)
IDR LLC Series B units (32, 875 units vested at December 31, 2017 and September 30, 2018)	35,289	35,474
Total partners' capital	25,126	15,608
Total liabilities and partners' capital	$ 42,258	$ 29,759

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - shares	Sep. 30, 2018	Dec. 31, 2017
Condensed Consolidated Balance Sheets
Partner’ capital, shares issued	186,199,995	186,181,975
Partner’ capital, shares outstanding	186,209,369	186,181,975
IDR LLC Series B units vested	32,875	32,875

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Consolidated Statements of Operations and Comprehensive Income
Equity in earnings of Antero Midstream Partners LP	$ 37,816	$ 19,067	$ 99,414	$ 45,948
Total income	37,816	19,067	99,414	45,948
General and administrative expense	2,229	615	5,557	5,922
Equity-based compensation	8,574	8,317	26,319	26,271
Total operating expenses	10,803	8,932	31,876	32,193
Operating income	27,013	10,135	67,538	13,755
Interest expense, net	(68)		(82)
Income before income taxes	26,945	10,135	67,456	13,755
Provision for income taxes	(8,917)	(7,157)	(22,236)	(17,337)
Net income (loss) and comprehensive income (loss)	18,028	2,978	45,220	(3,582)
Net income attributable to vested Series B units	(598)		(1,517)
Pre-IPO net income attributed to parent				4,939
Net income (loss) attributable to common shareholders	$ 17,430	$ 2,978	$ 43,703	$ 1,357
Net income (loss) per common share - basic and diluted	$ 0.09	$ 0.02	$ 0.23	$ 0.01
Weighted average number of common shares outstanding - basic	186,208	186,173	186,199,000	186,172,000
Weighted average number of common shares outstanding - diluted	186,208,000	191,175,000	186,199,000	191,191,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Partners' Capital - USD ($) $ in Thousands	Common Shares Representing Limited Partner Interests	Antero Resources Midstream Management LLC Members' Equity	Series B Unitholders	Total
Balance at Dec. 31, 2016		$ 10,269		$ 10,269
Partners' Capital
Net income (loss) and comprehensive income (loss)		(3,299)		(3,299)
Equity-based compensation		7,678		7,678
Balance at Mar. 31, 2017		14,648		14,648
Balance at Dec. 31, 2016		10,269		10,269
Partners' Capital
Net income (loss) and comprehensive income (loss)				(3,582)
Balance at Sep. 30, 2017	$ 8,680			8,680
Balance at Mar. 31, 2017		14,648		14,648
Partners' Capital
Pre-IPO net (loss) and comprehensive (loss)		(1,640)		(1,640)
Pre-IPO equity-based compensation		2,559		2,559
Conversion of Antero Resources Midstream Management LLC to a limited partnership	15,567	$ (15,567)
Post-IPO net income (loss) and comprehensive income (loss)	(1,621)			(1,621)
Equity-based compensation	4,994			4,994
Balance at Jun. 30, 2017	18,940			18,940
Partners' Capital
Net income (loss) and comprehensive income (loss)				2,978
Post-IPO net income (loss) and comprehensive income (loss)	2,978			2,978
Equity-based compensation	7,696			7,696
Distributions to Antero Resources Investment LLC	(15,908)			(15,908)
Distributions	(5,026)			(5,026)
Balance at Sep. 30, 2017	8,680			8,680
Balance at Dec. 31, 2017	(19,866)		$ 35,474	15,608
Partners' Capital
Net income (loss) and comprehensive income (loss)	12,392		413	12,805
Equity-based compensation	7,777			7,777
Distributions	(13,964)		(783)	(14,747)
Balance at Mar. 31, 2018	(13,661)		35,104	21,443
Balance at Dec. 31, 2017	(19,866)		35,474	15,608
Partners' Capital
Net income (loss) and comprehensive income (loss)				45,220
Balance at Sep. 30, 2018	(10,163)		35,289	25,126
Balance at Mar. 31, 2018	(13,661)		35,104	21,443
Partners' Capital
Net income (loss) and comprehensive income (loss)	13,881		506	14,387
Equity-based compensation	7,777			7,777
Distributions	(20,109)		(414)	(20,523)
Balance at Jun. 30, 2018	(12,112)		35,196	23,084
Partners' Capital
Net income (loss) and comprehensive income (loss)	17,430		598	18,028
Equity-based compensation	7,795			7,795
Distributions	(23,276)		(505)	(23,781)
Balance at Sep. 30, 2018	$ (10,163)		$ 35,289	$ 25,126

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows provided by operating activities:
Net income (loss)	$ 45,220	$ (3,582)
Adjustment to reconcile net income (loss) to net cash provided by operating activities:
Equity in earnings of Antero Midstream Partners LP	(99,414)	(45,948)
Distributions received from Antero Midstream Partners LP	85,371	34,424
Amortization of deferred financing costs	90
Equity-based compensation	26,319	26,271
Changes in current assets and liabilities:
Prepaid expenses	(56)	(49)
Accounts payable and accrued liabilities	646	185
Income taxes payable	(636)	2,226
Net cash provided by operating activities	57,540	13,527
Cash flows used in financing activities:
Distributions to Antero Resources Investment LLC		(15,691)
Distributions to shareholders	(57,349)	(5,026)
Distributions to Series B unitholders	(1,702)
Payments of deferred financing costs	(230)
Net cash used in financing activities	(59,281)	(20,717)
Net increase (decrease) in cash	(1,741)	(7,190)
Cash, beginning of period	5,987	9,609
Cash, end of period	$ 4,246	$ 2,419

Business and Organization

Business and Organization	9 Months Ended
	Sep. 30, 2018
Business and Organization
Business and Organization	(1 ) Business and Organization (a) Overview Antero Midstream GP LP (“AMGP”) was originally formed as Antero Resources Midstream Management LLC (“ARMM”) in 2013, to become the general partner of Antero Midstream, a master limited partnership that is publicly traded on the New York Stock Exchange (NYSE: AM). On May 4, 2017, ARMM converted from a Delaware limited liability company to a Delaware limited partnership and changed its name to Antero Midstream GP LP in connection with our initial public offering (“IPO”). Unless the context otherwise requires, references to “we” and “our” refer to: (i) for the period prior to May 4, 2017, ARMM, and (ii) beginning on May 4, 2017, AMGP. We own 100% of the membership interests of Antero Midstream Partners GP LLC (“AMP GP”), which owns the non-economic general partner interest in Antero Midstream, and we own all of the Series A capital interests in IDR LLC, which owns the IDRs of Antero Midstream. IDR LLC also has Series B profits interests (“Series B Units”) outstanding that entitle the holders to receive up to 6% of the distributions that Antero Midstream makes on the IDRs in excess of $7.5 million per quarter, subject to certain vesting conditions (see Note 4 – Long-Term Incentive Plans). We are taxed as a corporation for U.S. federal income tax purposes and we refer to our outstanding limited partner interests as common shares. Our only income results from distributions made on the IDRs of Antero Midstream. The Antero Midstream IDRs entitle holders to receive cash distributions from Antero Midstream when distributions exceed certain target amounts (see Note 5 – Distributions from Antero Midstream). We are managed by our general partner, AMGP GP LLC (“AMGP GP”), which establishes the quarterly cash distribution payable to shareholders. AMGP GP has a board of directors appointed by the entities and individuals that collectively own 100% of the membership interest in our general partner. Following the completion of our IPO, certain of our directors and executive officers own AMGP common shares as well as Series B Units in IDR LLC. In addition, certain of our directors and executive officers own a portion of Antero Resources’ (NYSE: AR) common stock and Antero Midstream’s common units. We have an agreement with Antero Resources, under which Antero Resources provides certain general and administrative services to us for a fee of $ 0.5 million per year, subject to annual inflation adjustments. Antero Midstream was formed by Antero Resources to own, operate and develop midstream energy assets to service Antero Resources’ oil and gas producing assets. Both Antero Midstream and Antero Resources’ assets are located in the Marcellus Shale and Utica Shale located in West Virginia and Ohio. Antero Midstream’s assets consist of gathering pipelines, compressor stations, and water handling and treatment systems, which provide midstream services to Antero Resources under long-term, fixed fee contracts. Antero Midstream also has a 15% equity interest in the gathering system of Stonewall Gas Gathering LLC and a 50% equity interest in a joint venture to develop processing and fractionation assets with MarkWest Energy Partners, L.P. Our results of operations, financial position and cash flows are dependent on the results of operations, financial position and cash flows of Antero Midstream. As a result, these unaudited condensed consolidated financial statements should be read in conjunction with Antero Midstream’s audited consolidated financial statements and notes thereto presented in its Annual Report on Form 10-K for the year ended December 31, 2017, as well as Antero Midstream’s unaudited condensed consolidated financial statements presented in its Quarterly Report on Form 10-Q for the quarter ended September 30, 2018. (b) Simplification Agreement On October 9, 2018, AMGP, Antero Midstream and certain of their affiliates entered into a Simplification Agreement (as may be amended from time to time, the “Simplification Agreement”), pursuant to which, among other things, (1) AMGP will be converted from a limited partnership to a corporation under the laws of the State of Delaware, to be named Antero Midstream Corporation (which is referred to as “New AM” and the conversion, the “Conversion”); (2) an indirect, wholly owned subsidiary of New AM will be merged with and into Antero Midstream, with Antero Midstream surviving the merger as an indirect, wholly owned subsidiary of New AM (the “Merger”) and (3) all the issued and outstanding Series B Units will be exchanged for an aggregate of approximately 17.35 million shares of New AM’s common stock (the “Series B Exchange”). The shares of New AM Common Stock to be received will be subject to the same vesting conditions to which the Series B Units are currently subject, with one-third fully vested, one-third scheduled to vest at December 31, 2018 and one-third scheduled to vest at December 31, 2019. With respect to the Series B Units and shares of New AM Common Stock scheduled to vest on December 31, 2019, the holders of Series B Units have agreed to forego any distributions from IDR Holdingas and any dividends from New AM that are paid with respect to such units or shares, as applicable, during the twelve months ended December 31, 2019. The Conversion, the Merger, the Series B Exchange and the other transactions contemplated by the Simplification Agreement are collectively referred to as the “Transactions”. As a result of the Transactions, Antero Midstream will be a wholly owned subsidiary of New AM and former shareholders of AMGP and unitholders of the Partnership will each own New AM’s common stock. At the effective time of the Merger, in exchange for each of Antero Midstream’s common units held by Antero Midstream’s unitholders other than Antero Resources (the “AM Public Unitholders”), (1) each AM Public Unitholder will be entitled to receive, at its election and subject to proration, one of (i) $3.415 in cash without interest and 1.6350 shares of New AM’s common stock for each of Antero Midstream’s common units held (the “Public Mixed Consideration”); (ii) 1.6350 shares of New AM’s common stock plus an additional number of shares of New AM’s common stock equal to the quotient of (A) $3.415 and (B) the average of the 20-day volume-weighted average trading price per AMGP common share prior to the final election day for AM Public Unitholders (the “AMGP VWAP”), for each of Antero Midstream’s common units held (the “Public Stock Consideration”); or (iii) $3.415 in cash plus an additional amount of cash equal to the product of (A) 1.6350 and (B) the AMGP VWAP for each of Antero Midstream’s common units held (the “Public Cash Consideration”); and (2) in exchange for each of Antero Midstream’s common units held, Antero Resources will be entitled to receive, subject to certain adjustments (as described below), $3.00 in cash without interest and 1.6023 shares of New AM’s common stock (the “AR Mixed Consideration”). The aggregate cash to be paid as consideration for the Merger will be fixed at an amount equal to the aggregate amount of cash that would be paid if all AM Public Unitholders received the Public Mixed Consideration and Antero Resources received the AR Mixed Consideration, which is approximately $598 million (the “Available Cash”). However, if Available Cash exceeds the cash consideration elected to be received by the AM Public Unitholders (the amount of such excess, “Excess Available Cash”), Antero Resources may elect to increase the total amount of cash it receives as a part of the AR Mixed Consideration up to an amount equal to the Excess Available Cash. To the extent Antero Resources elects to receive additional cash, the number of shares it receives will be reduced accordingly based on the AMGP VWAP. In addition, the Merger Consideration each AM Public Unitholder will receive may be prorated in the event that more cash or equity is elected to be received than what would otherwise have been paid if all AM Public Unitholders received the Public Mixed Consideration and Antero Resources received the AR Mixed Consideration. The closing of the Transactions is expected in the first quarter of 2019, subject to the satisfaction or waiver of customary closing conditions, including the approval of the Simplification Agreement, the Merger and the other Transactions contemplated thereby, as applicable, by Antero Midstream’s common unitholders and AMGP’s shareholders. AMGP and the Partnership expect to fund the cash portion of the merger consideration with borrowings under Antero Midstream’s revolving credit facility. Also on October 9, 2018, in connection with the entry into the Simplification Agreement, (1) Antero Midstream entered into a voting agreement with AMGP’s shareholders owning a majority of the outstanding AMGP common shares, pursuant to which, among other things, such shareholders agreed to vote in favor of the Transactions, (2) AMGP entered into a voting agreement with Antero Resources, pursuant to which, among other things, Antero Resources agreed to vote in favor of the Transactions and (3) AMGP, Antero Resources, certain funds affiliated with Warburg Pincus LLC and Yorktown Partners LLC (together, the “Sponsor Holders”), Paul M. Rady and Glen C. Warren, Jr. (Messrs. Rady and Warren together, the “Management Holders”) entered into a Stockholders’ Agreement, pursuant to which, among other things, Antero Resources, the Sponsor Holders and the Management Holders will have the ability to designate members of the New AM board of directors under certain circumstances, effective as the closing of the Transactions.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	(2) Summary of Significant Accounting Policies (a) Basis of Presentation These unaudited condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) applicable to interim financial information. The accompanying unaudited condensed consolidated financial statements of AMGP have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and, accordingly, do not include all of the information and footnotes required by GAAP for complete consolidated financial statements. In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments (consisting of normal and recurring accruals) considered necessary to fairly present AMGP’s financial position as of December 31, 2017 and September 30, 2018, and its results of operations for the three and nine months ended September 30, 2017 and 2018 and its cash flows for nine months ended September 30, 2017 and 2018. AMGP has no items of other comprehensive income (loss); therefore, its net income (loss) is identical to its comprehensive income (loss). Operating results for the period ended September 30, 2018 are not necessarily indicative of the results that may be expected for the full year. As of the date these unaudited condensed consolidated financial statements were filed with the SEC, the Partnership completed its evaluation of potential subsequent events for disclosure and no items requiring disclosure were identified other than as disclosed in Note 9 – Subsequent Events. (b) Principles of Consolidation The unaudited condensed consolidated financial statements include the accounts of AMGP, AMP GP (its wholly-owned subsidiary), and IDR LLC. (c) Investment in Antero Midstream AMGP has determined that Antero Midstream is a variable interest entity (“VIE”) for which we are not the primary beneficiary and therefore, do not consolidate. We have concluded that Antero Resources is the primary beneficiary of Antero Midstream and Antero Resources should consolidate Antero Midstream’s financial results. Antero Resources is the primary beneficiary based on its power to direct the activities that most significantly impact Antero Midstream’s economic performance and its obligations to absorb losses or receive benefits of Antero Midstream that could be significant to Antero Midstream. Antero Resources owns approximately 52.9% of the outstanding limited partner interests in Antero Midstream and its officers and management group also act as management of Antero Midstream. Antero Midstream was formed to own, operate, and develop midstream energy assets to service Antero Resources’ production under long term contracts as described herein. We do not own any limited partnership interests in Antero Midstream and have no capital interests in Antero Midstream. We have not provided and do not anticipate providing financial support to Antero Midstream. Antero Resources and Antero Midstream have contracts with 20-year initial terms and automatic renewal provisions, whereby Antero Resources has dedicated the rights for gathering and compression, and water handling and treatment services to Antero Midstream on a fixed-fee basis. Such dedications cover a substantial portion of Antero Resources’ current acreage and future acquired acreage, in each case, except for acreage that was already dedicated to other parties prior to entering into the service contracts or that was acquired subject to a pre-existing dedication. The contracts call for Antero Resources to present, in advance, drilling and completion plans in order for Antero Midstream to put in place gathering and compression, water handling, and gas processing assets to service Antero Resources’ assets. The drilling and completion capital investment decisions made by Antero Resources control the development and operation of all of Antero Midstream’s assets. Antero Resources therefore controls the activities that most significantly impact Antero Midstream’s economic performance. Because of these contractual obligations and the capital requirements related to these obligations, Antero Midstream has devoted and, for the foreseeable future, will devote substantially all of its resources to servicing Antero Resources’ operations. Additionally, revenues from Antero Resources will provide substantially all of Antero Midstream’s financial support and therefore, its ability to finance its operations. Because of the long term contractual commitment to support Antero Resources’ substantial growth plans, Antero Midstream will be practically and physically constrained from providing any substantive amount of services to other parties. AMGP’s ownership of the non-economic general partner interest in Antero Midstream provides it with significant influence over Antero Midstream, but not control over the decisions that most significantly impact the economic performance of Antero Midstream. AMGP’s indirect ownership of the IDRs of Antero Midstream entitles it to receive cash distributions from Antero Midstream when distributions exceed certain target amounts. Our ownership of these interests does not require us to provide financial support to Antero Midstream. We obtained these interests upon its formation for no consideration. Therefore, they have no cost basis and are classified as long term investments. Our share of Antero Midstream’s earnings as a result of our ownership of the IDRs is accounted for using the equity method of accounting. AMGP recognizes distributions earned from Antero Midstream as “Equity in earnings of Antero Midstream Partners LP” on its statement of operations in the period in which they are earned and are allocated to its capital account. Our long term interest in the IDRs on the balance sheet is recorded in “Investment in Antero Midstream Partners LP.” The ownership of the general partner interests and IDRs do not provide AMGP with any claim to the assets of Antero Midstream other than the balance in its Antero Midstream capital account. Income related to the IDRs is recognized as earned and increases AMGP’s capital account and equity investment. When these distributions are paid to us, they reduce our capital account and our equity investment in Antero Midstream. See Note 5—Distributions from Antero Midstream. (d) Use of Estimates The preparation of the unaudited condensed consolidated financial statements and notes in conformity with GAAP requires that management formulate estimates and assumptions that affect income, expenses, assets, and liabilities. Changes in facts and circumstances or discovery of new information may result in revised estimates, and actual results could differ from those estimates. (e) Income Taxes AMGP regularly reviews its tax positions in each significant taxing jurisdiction during the process of evaluating our tax provision. AMGP makes adjustments to its tax provision when: (i) facts and circumstances regarding a tax position change, causing a change in management’s judgment regarding that tax position; and/or (ii) a tax position is effectively settled with a tax authority at a differing amount. Equity-based compensation expense related to the Series B Units and certain IPO costs that are not deductible for federal income tax purposes. These non-deductible expenses and costs, along with the effect of state taxes, account for the difference between the federal tax rate of 35% and 21% for the three and nine months ended September 30, 2017 and 2018, respectively, and the effective rate of income tax expense for financial reporting purposes. (f) General and Administrative Expenses General and administrative costs incurred pre-IPO in 2017 primarily relate to legal and other costs incurred in connection with our IPO. Post-IPO general and administrative expense consists primarily of management fees paid to Antero Resources, and other legal and administrative expenses. Additionally, in connection with the formation of a conflicts committee of the board of directors of the Partnership’s general partner to consider potential transactions involving us in connection with Antero Resources’ and Antero Midstream’s efforts to explore, review, and evaluate potential measures related to its valuation, the conflicts committee retained an investment advisor and attorneys. The agreement with the investment advisor calls for a $2 million retainer fee, which has been expensed. Attorneys’ fees related to this matter are charged to expense as incurred. (g) Fair Value Measures The Financial Accounting Standards Board (the “FASB”) Accounting Standards Codification Topic 820, Fair Value Measurements and Disclosures , clarifies the definition of fair value, establishes a framework for measuring fair value, and expands disclosures about fair value measurements. This guidance also relates to all nonfinancial assets and liabilities that are not recognized or disclosed on a recurring basis (e.g., the initial recognition of asset retirement obligations and impairments of long‑lived assets). The fair value is the price that we estimate would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. A fair value hierarchy is used to prioritize inputs to valuation techniques used to estimate fair value. An asset or liability subject to the fair value requirements is categorized within the hierarchy based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. The highest priority (Level 1) is given to unadjusted quoted market prices in active markets for identical assets or liabilities, and the lowest priority (Level 3) is given to unobservable inputs. Level 2 inputs are data, other than quoted prices included within Level 1, which are observable for the asset or liability, either directly or indire ctly. (h) Net Income per Common Share Net income per common share – basic for each period is computed by dividing net income attributable to common shareholders by the basic weighted average number of common shares outstanding during the period. Net income per common share – diluted for each period is computed after giving consideration to the potential dilution from outstanding Series B Units, calculated using the if-converted method. During the periods in which AMGP incurs a net loss, diluted weighted average shares outstanding are equal to basic weighted average common shares outstanding because the effect of all equity awards is anti-dilutive. Based on AMGP’s market capitalization as of September 30, 2018, 4,091,741 AMGP shares would be issuable upon conversion of all outstanding Series B Units. The effect of these awards is anti-dilutive for the three and nine months ended September 30, 2018 , and thus, our diluted net income per common share for the three and nine months ended September 30, 2018 is equal to its basic net income per common share. (i) Recently Adopted Accounting Standard On June 20, 2018, the FASB issued Accounting Standards Update (“ASU”) No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting , which aligns the accounting for employee and nonemployee share-based payments. The new standard becomes effective for AMGP on January 1, 2019. Early adoption of the standard is permitted. The standard requires a cumulative-effect adjustment to partners’ capital at the beginning of the fiscal year of adoption. AMGP has elected to adopt the standard as of October 1, 2018. No cumulative-effect adjustment to partners’ capital will be required as the awards were remeasured to fair value as of September 30, 2018. As a result of adopting this standard, AMGP will reclassify its $3 million liability for equity-based compensation to partners’ capital as of September 30, 2018 in the fourth quarter of 2018. See Note 4 – Long-Term Incentive Plans.

Credit Facility

Credit Facility	9 Months Ended
	Sep. 30, 2018
Credit Facility
Credit Facility	(3) Credit Facility On May 9, 2018, AMGP entered into a credit facility (the “Credit Facility”) with Wells Fargo Bank, National Association as lender (the “ Lender ”), which provides for a line of credit of up to $12 million. The maturity date of the Credit Facility is May 6, 2019. The Credit Facility is guaranteed by IDR LLC and secured by a pledge of the Series A capital interests in IDR LLC and the membership interests in AMP GP. Interest is payable on borrowings at a variable rate based on the base rate plus a margin rate of interest equal to 1.00% per annum. The base rate is the highest of (i) the Federal Funds Rate plus ½ of 1%, (ii) the rate of interest in effect for such day as publicly announced from time to time by the Lender as its “prime rate” and (iii) the Eurodollar Rate plus 1.00%. The Credit Facility contains customary events of default and various affirmative and negative covenants, including restrictions on incurring indebtedness, making investments and disposing of assets, and a requirement to completely repay amounts outstanding under the line of credit at least once each fiscal quarter. At September 30, 2018, AMGP had no borrowings under the Credit Facility.

Long-Term Incentive Plans

Long-Term Incentive Plans	9 Months Ended
	Sep. 30, 2018
Long-Term Incentive Plans
Long-Term Incentive Plans	(4) Long-Term Incentive Plans As of September 30, 2018, IDR LLC had 98,600 Series B Units authorized and outstanding that entitle the holders to receive up to 6% of the amount of the distributions that Antero Midstream makes on its IDRs in excess of $7.5 million per quarter, subject to certain vesting conditions. Series B Units issued to common law employees of AMGP, including officers of AMGP and Antero Resources employees who provide services directly to AMGP, are classified as equity awards. Series B Units issued to Antero Resources employees who are not common law employees of AMGP are classified as liability awards. IDR LLC has granted 92,000 Series B Units that are equity classified awards and 8,000 Series B Units that are liability classified awards. As of September 30, 2018, 500 Series B Units that were equity classified awards have been forfeited, and 900 Series B Units that were liability classified awards have been forfeited. The Series B Units vest ratably over a three year period. As of September 30, 2018, 32,875 Series B Units have vested. The holders of vested Series B Units have the right to exchange the units for common shares with a value equal to their pro rata share of up to 6% of our equity value in excess of $2.0 billion. In no event will the aggregate number of newly issued common shares exceed 6% of the total number of our issued and outstanding common shares. For equity classified awards, AMGP recognizes expense for the grant date fair value of the awards over the vesting period of the awards. Forfeitures are accounted for as they occur by reversing expense previously recognized for awards that were forfeited during the period. The grant date fair value of the Series B Unit awards was estimated using a Monte Carlo simulation using various assumptions including a floor equity value of $2.0 billion, expected volatility of 43% based on historical volatility of a peer group of publicly traded partnerships, a risk free rate of 2.45%, and expected IDR distributions based on internal estimates discounted based on a weighted average cost of capital assumption of 7.25%. Based on these assumptions, the estimated value of each Series B Unit was $999 when they were issued. The fair value measurement is based on significant inputs not observable in the market and thus, represents a Level 3 measurement within the fair value hierarchy. Any significant increases or decreases in management estimates and assumptions may result in a significantly higher or lower fair value measurement. The actual amount that may ultimately be realized by the holders of the Series B Unit awards in the future could be significantly higher or lower depending on AMGP’s market capitalization at the relevant time during the ten-year term when the Series B Units may be exchanged for our common shares, considering both share price and total number of shares outstanding at that time. For a discussion of the Series B Exchange in the event that the Transactions are consummated, see Note 1 – Business and Organization. For liability classified awards, AMGP recognized expense for the fair value of the awards over the vesting period of the awards. Forfeitures are accounted for as they occur by reversing expense previously recognized for awards that were forfeited during the period. AGMP updates its assumptions each reporting period based on new developments and adjusts such amounts to fair value based on revised assumptions, if applicable, over the vesting period. At September 30, 2018, the fair value of the liability classified Series B Unit awards was estimated using a Monte Carlo simulation using various assumptions including an equity value of $ 3.3 billion, expected volatility of 38% based on historical volatility of a peer group of publicly traded partnerships, a risk free rate of 3.00%, and expected IDR distributions based on internal estimates discounted based on a weighted average cost of capital assumption of 7.25%. Based on these assumptions, the estimated value of each Series B Unit at September 30, 2018 was $ 1,673 . The fair value measurement is based on significant inputs not observable in the market and thus, represents a Level 3 measurement within the fair value hierarchy. AMGP recognized expense of $8.4 million, of which $7.6 million was for equity classified awards and $0.8 million was for liability classified awards, during the three months ended September 30, 2018. AMGP recognized expense of $8.2 million, of which $7.6 million was for equity classified awards and $0.6 million was for liability classified awards, during the three months ended September 30, 2017. AMGP recognized expense of $25.8 million, of which $22.8 million was for equity classified awards and $3.0 million was for liability classified awards, during the nine months ended September 30, 2018. AMGP recognized expense of $26.2 million, of which $22.9 million was for equity classified awards and $3.3 million was for liability classified awards, during the nine months ended September 30, 2017. As of September 30, 2018, there was $43.0 million of unamortized compensation expense related to nonvested Series B Units that is expected to be recognized over the next 1.2 5 years. On April 17, 2017, AMGP adopted the Antero Midstream GP LP Long-Term Incentive Plan (“2017 LTIP”), pursuant to which certain non-employee directors of our general partner and certain officers, employees and consultants of Antero Resources are eligible to receive awards representing equity interests in AMGP. An aggregate of 930,851 common shares may be delivered pursuant to awards under the 2017 LTIP, subject to customary adjustments. As of September 30, 2018, 39,156 common shares have been granted. We recognized $0.1 million and $0.2 million in expense related to these grants in the three months ended September 30, 2017 and 2018 , respectively. We recognized $0.1 million and $0. 5 million in expense related to these grants in the nine months ended September 30, 2017 and 2018 , respectively. As of September 30, 2018, 891,695 common shares remain available for grant under the 2017 LTIP.

Distributions from Antero Midst

Distributions from Antero Midstream	9 Months Ended
	Sep. 30, 2018
Distributions from Antero Midstream
Distributions from Antero Midstream	(5) Distributions from Antero Midstream Antero Midstream’s partnership agreement provides for a target minimum quarterly distribution of $0.17 per common unit for each quarter, or $0.68 per unit on an annualized basis. If cash distributions to Antero Midstream’s unitholders exceed $0.1955 per common unit in any quarter, IDR LLC, as the holder of Antero Midstream’s IDRs, will receive distributions according to the following percentage allocations: Marginal Percentage Interest in Distributions Total Quarterly Distribution Antero Midstream Common Unitholders Holder of IDRs above $0.1955 up to $0.2125 85 % 15 % above $0.2125 up to $0.2550 75 % 25 % above $0.2550 50 % 50 % Distributions per common unit and distributions related to the IDRs were as follows for the periods indicated: Quarter Distribution Date Antero Midstream Distribution Amount Income Attributable to IDRs Q1 2017 May 10, 2017 $ $ 11,553 Q2 2017 August 16, 2017 $ $ 15,328 Q3 2017 November 16, 2017 $ $ 19,067 Q4 2017 February 13, 2018 $ $ 23,772 Q1 2018 May 18, 2018 $ $ 28,460 Q2 2018 August 17, 2018 $ $ 33,138 The board of directors of Antero Midstream’s general partner has declared a cash distribution of $0.44 per unit for the quarter ended September 30, 2018. The distribution will be payable on November 16, 2018 to unitholders of record as of November 2, 2018. The distribution attributable to the IDRs for the quarter ended September 30, 2018 is $ 37.8 million. Distributions attributable to the IDRs which relate to periods prior to May 9, 2017, the closing of our IPO, were distributed to Antero Investment prior to its liquidation.

Cash Distributions to Sharehold

Cash Distributions to Shareholders	9 Months Ended
	Sep. 30, 2018
Cash Distributions to Shareholders
Cash Distribution to Shareholders	(6) Cash Distributions to Shareholders The following table details the amount of quarterly distributions AMGP paid with respect to the quarter indicated (in thousands, except per share data): Distributions Quarter Record Date Distribution Date Common shareholders Antero Resources Investment Total Distributions per common share * May 9, 2017 September 13, 2017 $ — 15,908 15,908 * Q2 2017 August 3, 2017 August 23, 2017 5,026 — 5,026 $ Q3 2017 November 1, 2017 November 23, 2017 10,985 — 10,985 $ Total 2017 $ 16,011 15,908 31,919 Q4 2017 February 1, 2018 February 20, 2018 $ 13,964 — 13,964 $ Q1 2018 May 3, 2018 May 23, 2018 20,109 — 20,109 $ Q2 2018 August 2, 2018 August 22, 2018 23,276 — 23,276 $ Total 2018 $ 57,349 — 57,349 * Income relating to periods prior to May 9, 2017, the closing of our IPO, was distributed to Antero Investment prior to its liquidation.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2018
Related Party Transactions
Related Party Transactions	(7) Related Party Transactions Certain of AMGP’s shareholders, including members of its executive management group, own a significant interest in AMGP and, either through their representatives or directly, serve as members of the Board of Directors of Antero Resources and the Boards of Directors of the general partners of Antero Midstream and AMGP. These same groups or individuals own common stock in Antero Resources and limited partner interests in Antero Midstream. AMGP’s executive management group also manages the operations and business affairs of Antero Resources and Antero Midstream. For a discussion of the Series B Exchange in the event that the Transactions are consummated, see Note 1 - Business and Organization. Accrued liabilities and accounts payable at December 31, 2017 and September 30, 2018 includes less than $0.1 million and $0.1 million, respectively, payable to Antero Resources for general and administrative expenses.

Summarized Financial Informatio

Summarized Financial Information for Antero Midstream	9 Months Ended
	Sep. 30, 2018
Summarized Financial Information for Antero Midstream
Summarized Financial Information for Antero Midstream	(8) Summarized Financial Information for Antero Midstream Summarized financial information for Antero Midstream, our investee accounted for using the equity method of accounting, is included in this note. The following tables present summarized income statement and balance sheet information for Antero Midstream (in thousands). Summarized Antero Midstream Income Statement Information Three Months Ended September 30, Nine Months Ended September 30, 2017 2018 2017 2018 Revenues $ 193,629 266,205 562,165 746,771 Operating expenses 110,458 140,159 304,730 394,355 Operating income $ 83,171 126,046 257,435 352,416 Net income and comprehensive income 80,893 119,764 243,160 337,335 Net income attributable to incentive distribution rights (19,067) (37,816) (45,948) (99,414) Limited partners' interest in net income $ 61,826 81,948 197,212 237,921 Summarized Antero Midstream Balance Sheet Information December 31, 2017 September 30, 2018 Current assets $ 120,385 133,965 Non-current assets 2,921,824 3,280,863 Current liabilities 121,316 107,887 Non-current liabilities 1,404,424 1,742,379 Partners' capital $ 1,516,469 1,564,562

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2019
Subsequent Events
Subsequent Events	(9) Subsequent Events On October 9, 2018, AMGP, Antero Midstream and certain of their affiliates entered into a Simplification Agreement. See Note 1 – Business and Organization. On October 16, 2018, the board of directors of our general partner declared a cash distribution of $0. 144 per share for the quarter ended September 30, 2018. The distribution will be payable on November 21, 2018 to shareholders of record as of November 2, 2018.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Summary of Significant Accounting Policies
Basis of Presentation	(a) Basis of Presentation These unaudited condensed consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) applicable to interim financial information. The accompanying unaudited condensed consolidated financial statements of AMGP have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information and, accordingly, do not include all of the information and footnotes required by GAAP for complete consolidated financial statements. In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments (consisting of normal and recurring accruals) considered necessary to fairly present AMGP’s financial position as of December 31, 2017 and September 30, 2018, and its results of operations for the three and nine months ended September 30, 2017 and 2018 and its cash flows for nine months ended September 30, 2017 and 2018. AMGP has no items of other comprehensive income (loss); therefore, its net income (loss) is identical to its comprehensive income (loss). Operating results for the period ended September 30, 2018 are not necessarily indicative of the results that may be expected for the full year. As of the date these unaudited condensed consolidated financial statements were filed with the SEC, the Partnership completed its evaluation of potential subsequent events for disclosure and no items requiring disclosure were identified other than as disclosed in Note 9 – Subsequent Events.
Principles of Consolidation	(b) Principles of Consolidation The unaudited condensed consolidated financial statements include the accounts of AMGP, AMP GP (its wholly-owned subsidiary), and IDR LLC.
Investment in Antero Midstream	(c) Investment in Antero Midstream AMGP has determined that Antero Midstream is a variable interest entity (“VIE”) for which we are not the primary beneficiary and therefore, do not consolidate. We have concluded that Antero Resources is the primary beneficiary of Antero Midstream and Antero Resources should consolidate Antero Midstream’s financial results. Antero Resources is the primary beneficiary based on its power to direct the activities that most significantly impact Antero Midstream’s economic performance and its obligations to absorb losses or receive benefits of Antero Midstream that could be significant to Antero Midstream. Antero Resources owns approximately 52.9% of the outstanding limited partner interests in Antero Midstream and its officers and management group also act as management of Antero Midstream. Antero Midstream was formed to own, operate, and develop midstream energy assets to service Antero Resources’ production under long term contracts as described herein. We do not own any limited partnership interests in Antero Midstream and have no capital interests in Antero Midstream. We have not provided and do not anticipate providing financial support to Antero Midstream. Antero Resources and Antero Midstream have contracts with 20-year initial terms and automatic renewal provisions, whereby Antero Resources has dedicated the rights for gathering and compression, and water handling and treatment services to Antero Midstream on a fixed-fee basis. Such dedications cover a substantial portion of Antero Resources’ current acreage and future acquired acreage, in each case, except for acreage that was already dedicated to other parties prior to entering into the service contracts or that was acquired subject to a pre-existing dedication. The contracts call for Antero Resources to present, in advance, drilling and completion plans in order for Antero Midstream to put in place gathering and compression, water handling, and gas processing assets to service Antero Resources’ assets. The drilling and completion capital investment decisions made by Antero Resources control the development and operation of all of Antero Midstream’s assets. Antero Resources therefore controls the activities that most significantly impact Antero Midstream’s economic performance. Because of these contractual obligations and the capital requirements related to these obligations, Antero Midstream has devoted and, for the foreseeable future, will devote substantially all of its resources to servicing Antero Resources’ operations. Additionally, revenues from Antero Resources will provide substantially all of Antero Midstream’s financial support and therefore, its ability to finance its operations. Because of the long term contractual commitment to support Antero Resources’ substantial growth plans, Antero Midstream will be practically and physically constrained from providing any substantive amount of services to other parties. AMGP’s ownership of the non-economic general partner interest in Antero Midstream provides it with significant influence over Antero Midstream, but not control over the decisions that most significantly impact the economic performance of Antero Midstream. AMGP’s indirect ownership of the IDRs of Antero Midstream entitles it to receive cash distributions from Antero Midstream when distributions exceed certain target amounts. Our ownership of these interests does not require us to provide financial support to Antero Midstream. We obtained these interests upon its formation for no consideration. Therefore, they have no cost basis and are classified as long term investments. Our share of Antero Midstream’s earnings as a result of our ownership of the IDRs is accounted for using the equity method of accounting. AMGP recognizes distributions earned from Antero Midstream as “Equity in earnings of Antero Midstream Partners LP” on its statement of operations in the period in which they are earned and are allocated to its capital account. Our long term interest in the IDRs on the balance sheet is recorded in “Investment in Antero Midstream Partners LP.” The ownership of the general partner interests and IDRs do not provide AMGP with any claim to the assets of Antero Midstream other than the balance in its Antero Midstream capital account. Income related to the IDRs is recognized as earned and increases AMGP’s capital account and equity investment. When these distributions are paid to us, they reduce our capital account and our equity investment in Antero Midstream. See Note 5—Distributions from Antero Midstream.
Use of Estimates	(d) Use of Estimates The preparation of the unaudited condensed consolidated financial statements and notes in conformity with GAAP requires that management formulate estimates and assumptions that affect income, expenses, assets, and liabilities. Changes in facts and circumstances or discovery of new information may result in revised estimates, and actual results could differ from those estimates.
Income Taxes	(e) Income Taxes AMGP regularly reviews its tax positions in each significant taxing jurisdiction during the process of evaluating our tax provision. AMGP makes adjustments to its tax provision when: (i) facts and circumstances regarding a tax position change, causing a change in management’s judgment regarding that tax position; and/or (ii) a tax position is effectively settled with a tax authority at a differing amount. Equity-based compensation expense related to the Series B Units and certain IPO costs that are not deductible for federal income tax purposes. These non-deductible expenses and costs, along with the effect of state taxes, account for the difference between the federal tax rate of 35% and 21% for the three and nine months ended September 30, 2017 and 2018, respectively, and the effective rate of income tax expense for financial reporting purposes.
General and Administrative Expenses	(f) General and Administrative Expenses General and administrative costs incurred pre-IPO in 2017 primarily relate to legal and other costs incurred in connection with our IPO. Post-IPO general and administrative expense consists primarily of management fees paid to Antero Resources, and other legal and administrative expenses. Additionally, in connection with the formation of a conflicts committee of the board of directors of the Partnership’s general partner to consider potential transactions involving us in connection with Antero Resources’ and Antero Midstream’s efforts to explore, review, and evaluate potential measures related to its valuation, the conflicts committee retained an investment advisor and attorneys. The agreement with the investment advisor calls for a $2 million retainer fee, which has been expensed. Attorneys’ fees related to this matter are charged to expense as incurred.
Fair Value Measures	(g) Fair Value Measures The Financial Accounting Standards Board (the “FASB”) Accounting Standards Codification Topic 820, Fair Value Measurements and Disclosures , clarifies the definition of fair value, establishes a framework for measuring fair value, and expands disclosures about fair value measurements. This guidance also relates to all nonfinancial assets and liabilities that are not recognized or disclosed on a recurring basis (e.g., the initial recognition of asset retirement obligations and impairments of long‑lived assets). The fair value is the price that we estimate would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. A fair value hierarchy is used to prioritize inputs to valuation techniques used to estimate fair value. An asset or liability subject to the fair value requirements is categorized within the hierarchy based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. The highest priority (Level 1) is given to unadjusted quoted market prices in active markets for identical assets or liabilities, and the lowest priority (Level 3) is given to unobservable inputs. Level 2 inputs are data, other than quoted prices included within Level 1, which are observable for the asset or liability, either directly or indire ctly.
Net Income per Common Share	(h) Net Income per Common Share Net income per common share – basic for each period is computed by dividing net income attributable to common shareholders by the basic weighted average number of common shares outstanding during the period. Net income per common share – diluted for each period is computed after giving consideration to the potential dilution from outstanding Series B Units, calculated using the if-converted method. During the periods in which AMGP incurs a net loss, diluted weighted average shares outstanding are equal to basic weighted average common shares outstanding because the effect of all equity awards is anti-dilutive. Based on AMGP’s market capitalization as of September 30, 2018, 4,091,741 AMGP shares would be issuable upon conversion of all outstanding Series B Units. The effect of these awards is anti-dilutive for the three and nine months ended September 30, 2018 , and thus, our diluted net income per common share for the three and nine months ended September 30, 2018 is equal to its basic net income per common share.
Recently Issued Accounting Standards	(i) Recently Adopted Accounting Standard On June 20, 2018, the FASB issued Accounting Standards Update (“ASU”) No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting , which aligns the accounting for employee and nonemployee share-based payments. The new standard becomes effective for AMGP on January 1, 2019. Early adoption of the standard is permitted. The standard requires a cumulative-effect adjustment to partners’ capital at the beginning of the fiscal year of adoption. AMGP has elected to adopt the standard as of October 1, 2018. No cumulative-effect adjustment to partners’ capital will be required as the awards were remeasured to fair value as of September 30, 2018. As a result of adopting this standard, AMGP will reclassify its $3 million liability for equity-based compensation to partners’ capital as of September 30, 2018 in the fourth quarter of 2018. See Note 4 – Long-Term Incentive Plans

Distributions from Antero Mid_2

Distributions from Antero Midstream (Tables)	9 Months Ended
	Sep. 30, 2018
Distributions from Antero Midstream
Summary of percentage allocations for distributions	Marginal Percentage Interest in Distributions Total Quarterly Distribution Antero Midstream Common Unitholders Holder of IDRs above $0.1955 up to $0.2125 85 % 15 % above $0.2125 up to $0.2550 75 % 25 % above $0.2550 50 % 50 %
Summary of quarterly cash distribution to partners	Quarter Distribution Date Antero Midstream Distribution Amount Income Attributable to IDRs Q1 2017 May 10, 2017 $ $ 11,553 Q2 2017 August 16, 2017 $ $ 15,328 Q3 2017 November 16, 2017 $ $ 19,067 Q4 2017 February 13, 2018 $ $ 23,772 Q1 2018 May 18, 2018 $ $ 28,460 Q2 2018 August 17, 2018 $ $ 33,138

Cash Distributions to Shareho_2

Cash Distributions to Shareholders (Tables)	9 Months Ended
	Sep. 30, 2018
Cash Distributions to Shareholders
Schedule of quarterly distributions AMGP paid	The following table details the amount of quarterly distributions AMGP paid with respect to the quarter indicated (in thousands, except per share data): Distributions Quarter Record Date Distribution Date Common shareholders Antero Resources Investment Total Distributions per common share * May 9, 2017 September 13, 2017 $ — 15,908 15,908 * Q2 2017 August 3, 2017 August 23, 2017 5,026 — 5,026 $ Q3 2017 November 1, 2017 November 23, 2017 10,985 — 10,985 $ Total 2017 $ 16,011 15,908 31,919 Q4 2017 February 1, 2018 February 20, 2018 $ 13,964 — 13,964 $ Q1 2018 May 3, 2018 May 23, 2018 20,109 — 20,109 $ Q2 2018 August 2, 2018 August 22, 2018 23,276 — 23,276 $ Total 2018 $ 57,349 — 57,349 * Income relating to periods prior to May 9, 2017, the closing of our IPO, was distributed to Antero Investment prior to its liquidation.

Summarized Financial Informat_2

Summarized Financial Information for Antero Midstream (Tables)	9 Months Ended
	Sep. 30, 2018
Summarized Financial Information for Antero Midstream
Schedule of summarized income statement and balance sheet information for Antero Midstream	. The following tables present summarized income statement and balance sheet information for Antero Midstream (in thousands). Summarized Antero Midstream Income Statement Information Three Months Ended September 30, Nine Months Ended September 30, 2017 2018 2017 2018 Revenues $ 193,629 266,205 562,165 746,771 Operating expenses 110,458 140,159 304,730 394,355 Operating income $ 83,171 126,046 257,435 352,416 Net income and comprehensive income 80,893 119,764 243,160 337,335 Net income attributable to incentive distribution rights (19,067) (37,816) (45,948) (99,414) Limited partners' interest in net income $ 61,826 81,948 197,212 237,921 Summarized Antero Midstream Balance Sheet Information December 31, 2017 September 30, 2018 Current assets $ 120,385 133,965 Non-current assets 2,921,824 3,280,863 Current liabilities 121,316 107,887 Non-current liabilities 1,404,424 1,742,379 Partners' capital $ 1,516,469 1,564,562

Business and Organization (Deta

Business and Organization (Details)	9 Months Ended
	Sep. 30, 2018USD ($)
Antero Midstream Partners GP LLC
Business and Organization
Capital interest (as a percent)	100.00%
IDR LLC
Business and Organization
Percentage of amount of quarterly distribution in excess of threshold limit	6.00%
Threshold limit for quarterly distribution	$ 7,500,000
AMGP GP
Business and Organization
Percentage of ownership of the membership interest in general partner	100
Antero Resources
Business and Organization
General and administrative fee	$ 500,000
Stonewall Gas Gathering LLC
Business and Organization
Ownership percentage	15.00%
Mark West Energy Partners, L. P.
Business and Organization
Capital interest (as a percent)	50.00%

Business and Organization - Sim

Business and Organization - Simplification (Details) - Simplification Agreement - Subsequent event - Forecast $ / shares in Units, $ in Millions	Oct. 09, 2018USD ($)$ / sharesshares
Antero Resources
Business and Organization
Cash without interest | $ / shares	$ 3
Number of new shares issued	1.6023
AM Public Unitholders
Business and Organization
Cash without interest | $ / shares	$ 3.415
Number of new shares issued	1.6350
Threshold days	20 days
New AM
Business and Organization
New AM's Common stock in exchange of Series B units	17,350,000
Percentage of shares fully vested	33.33%
Percentage of shares scheduled to vest at December 31, 2018	33.33%
Percentage of shares scheduled to vest at December 31, 2019	33.33%
Aggregate cash consideration to be paid | $	$ 598

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Significant Accounting Policies
Partners' capital	$ 25,126	$ 8,680	$ 25,126	$ 8,680	$ 23,084	$ 21,443	$ 15,608	$ 18,940	$ 14,648	$ 10,269
Income taxes
Statutory U.S. Federal tax rate (as a percent)	21.00%	35.00%	21.00%	35.00%
General and Administrative Expenses
Investment advisor retainer fee			$ 2,000
Net Income (Loss) per Common Share
Diluted weighted average number of common shares outstanding	186,208,000	191,175,000	186,199,000	191,191,000
Antidilutive securities excluded from computation of earnings per share			4,091,741
Antero Midstream
Significant Accounting Policies
Partners' capital	$ 0		$ 0
Consideration paid			0
Cost basis of interests	$ 0		$ 0
Antero Resources | Antero Midstream
Significant Accounting Policies
Ownership percentage	52.90%		52.90%
Contract term			20 years

Long-Term Debt (Details)

Long-Term Debt (Details) - Credit Facility - USD ($) $ in Millions	May 09, 2018	Sep. 30, 2018
Long-Term debt
Maximum amount of the Credit Facility	$ 12
Borrowings outstanding		$ 0
Base Rate
Long-Term debt
Margin rate added to base rate (as a percent)	1.00%
Federal Funds Rate
Long-Term debt
Margin rate added to base rate (as a percent)	0.50%
Prime Rate
Long-Term debt
Margin rate added to base rate (as a percent)	1.00%

Long-Term Incentive Plan (Detai

Long-Term Incentive Plan (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended		17 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017	Apr. 17, 2017
Aggregate disclosure
Units vested	32,875		32,875		32,875	32,875
2017 LTIP
Aggregate disclosure
Expense recognized	$ 0.2	$ 0.1	$ 0.5	$ 0.1
Number of common shares may be delivered pursuant to awards, subject to customary adjustments							930,851
Awards granted					39,156
Remaining shares granted	891,695		891,695		891,695
IDR LLC
Long-Term Incentive Plan
Percentage of amount of quarterly distribution in excess of threshold limit			6.00%
Threshold limit for quarterly distribution			$ 7.5
Aggregate disclosure
Units vested	32,875		32,875		32,875
IDR LLC | Series B unit awards
Long-Term Incentive Plan
Authorized units	98,600		98,600		98,600
Outstanding units	98,600		98,600		98,600
Threshold limit for quarterly distribution			$ 7.5
Threshold limit for conversion of units to common shares	$ 2,000		$ 2,000		$ 2,000
Assumptions:
Vesting period			3 years
Aggregate disclosure
Expense recognized	8.4	8.2	$ 25.8	26.2
Unamortized compensation expense related to nonvested Series B units	43		$ 43		43
Weighted average period for recognizing unrecognized stock-based compensation expense			1 year 3 months
IDR LLC | Series B unit awards | Maximum
Long-Term Incentive Plan
Percentage of amount of quarterly distribution in excess of threshold limit			6.00%
Percentage of amount of equity value in excess of threshold limit for conversion of units to common shares			6.00%
Percentage of newly issued common shares to the total number of issued and outstanding common shares allowed			6.00%
IDR LLC | Series B Unit Awards classified as equity
Assumptions:
Floor equity value	2,000		$ 2,000		2,000
Vesting period			10 years
Expected volatility (as a percent)			43.00%
Risk free rate (as a percent)			2.45%
Weighted average cost of capital (as a percent)			7.25%
Estimated value (in dollars per unit)			$ 999
Aggregate disclosure
Expense recognized	7.6	7.6	$ 22.8	22.9
Awards granted			92,000
Awards forfeited			500
IDR LLC | Series B Unit Awards classified as liability
Assumptions:
Floor equity value	3,300		$ 3,300		$ 3,300
Expected volatility (as a percent)			38.00%
Risk free rate (as a percent)			3.00%
Weighted average cost of capital (as a percent)			7.25%
Estimated value (in dollars per unit)			$ 1,673
Aggregate disclosure
Expense recognized	$ 0.8	$ 0.6	$ 3	$ 3.3
Awards granted			8,000
Awards forfeited			900

Distributions from Antero Mid_3

Distributions from Antero Midstream (Details) $ / shares in Units, $ in Thousands

Aug. 17, 2018$ / shares

May 23, 2018$ / shares

Feb. 20, 2018$ / shares

Nov. 23, 2017$ / shares

Aug. 23, 2017$ / shares

Sep. 30, 2018USD ($)$ / shares

Jun. 30, 2018USD ($)$ / shares

Mar. 31, 2018USD ($)$ / shares

Dec. 31, 2017USD ($)$ / shares

Sep. 30, 2017USD ($)$ / shares

Jun. 30, 2017USD ($)$ / shares

Mar. 31, 2017USD ($)$ / shares

Sep. 30, 2018$ / shares$ / item

Partnership equity and distributions

Cash distribution paid | $ / shares

$ 0.1250

$ 0.1080

$ 0.0750

$ 0.0590

$ 0.0270

General Partner

Partnership equity and distributions

Total Distribution | $

$ 37,800

$ 33,138

$ 28,460

$ 23,772

$ 19,067

$ 15,328

$ 11,553

Common units

Partnership equity and distributions

Cash distribution declared | $ / shares

$ 0.4150

$ 0.3900

$ 0.3650

$ 0.3400

$ 0.3200

$ 0.3000

$0.2550

Partnership equity and distributions

Pro rata cash distribution to the holders of common and subordinate units

0.2550

Minimum | Above $0.1955 up to $0.2125

Partnership equity and distributions

Pro rata cash distribution to the holders of common and subordinate units

0.1955

Minimum | Above $0.2125 up to $0.2550

Partnership equity and distributions

Pro rata cash distribution to the holders of common and subordinate units

0.2125

Maximum | Above $0.1955 up to $0.2125

Partnership equity and distributions

Pro rata cash distribution to the holders of common and subordinate units

0.2125

Maximum | Above $0.2125 up to $0.2550

Partnership equity and distributions

Pro rata cash distribution to the holders of common and subordinate units

0.2550

Antero Midstream

Partnership equity and distributions

Minimum quarterly cash distribution (per unit)

0.17

Annual cash distribution (per unit)

0.68

Minimum cash distributions to trigger unitholder and general partner distributions | $ / shares

$ 0.1955

Antero Midstream | General Partner

Partnership equity and distributions

Cash distribution declared | $ / shares

$ 0.44

Antero Midstream | Above $0.1955 up to $0.2125

Partnership equity and distributions

Unitholders marginal percentage interest in distribution

85.00%

General Partners marginal percentage interest in distribution

15.00%

Antero Midstream | Above $0.2125 up to $0.2550

Partnership equity and distributions

Unitholders marginal percentage interest in distribution

75.00%

General Partners marginal percentage interest in distribution

25.00%

Antero Midstream | Above $0.2550

Partnership equity and distributions

Unitholders marginal percentage interest in distribution

50.00%

General Partners marginal percentage interest in distribution

50.00%

Cash Distributions to Shareho_3

Cash Distributions to Shareholders (Details) - USD ($) $ / shares in Units, $ in Thousands	Aug. 17, 2018	May 23, 2018	Feb. 20, 2018	Nov. 23, 2017	Sep. 13, 2017	Aug. 23, 2017	Sep. 30, 2018	Dec. 31, 2017
Quarterly distribution paid
Distributions	$ 23,276	$ 20,109	$ 13,964	$ 10,985	$ 15,908	$ 5,026	$ 57,349	$ 31,919
Distributions per common share	$ 0.1250	$ 0.1080	$ 0.0750	$ 0.0590		$ 0.0270
Common shareholders
Quarterly distribution paid
Distributions	$ 23,276	$ 20,109	$ 13,964	$ 10,985		$ 5,026	$ 57,349	16,011
Antero Resources Investment
Quarterly distribution paid
Distributions					$ 15,908			$ 15,908

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Allocation of costs
Payable to related party	$ 0.1
Maximum
Allocation of costs
Payable to related party		$ 0.1

Summarized Financial Informat_3

Summarized Financial Information for Antero Midstream (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Summarized Balance Sheet Information
Current assets	$ 133,965		$ 133,965		$ 120,385
Non-current assets	3,280,863		3,280,863		2,921,824
Current liabilities	107,887		107,887		121,316
Non-current liabilities	1,742,379		1,742,379		1,404,424
Partners' capital	1,564,562		1,564,562		$ 1,516,469
Antero Midstream
Summarized Income Statement Information
Revenues	266,205	$ 193,629	746,771	$ 562,165
Operating expenses	140,159	110,458	394,355	304,730
Operating income	126,046	83,171	352,416	257,435
Net income and comprehensive income	119,764	80,893	337,335	243,160
Net income attributable to incentive distribution rights	(37,816)	(19,067)	(99,414)	(45,948)
Limited partners' interest in net income	$ 81,948	$ 61,826	$ 237,921	$ 197,212

Subsequent Events (Details)

Subsequent Events (Details)	Oct. 16, 2019$ / shares
Subsequent event | AMGP GP
Subsequent events
Cash distributions declared (in dollars per share)	$ 0.144