Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2018	Oct. 26, 2018
Document and Entity Information
Entity Registrant Name	Antero Midstream Partners LP
Entity Central Index Key	0001598968
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	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		187,050,402
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q3

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents		$ 8,363
Accounts receivable - Antero Resources	$ 115,905	110,182
Accounts receivable - third party	16,586	1,170
Prepaid expenses	1,474	670
Total current assets	133,965	120,385
Property and equipment:
Property and equipment, net	2,873,874	2,605,602
Investments in unconsolidated affiliates	392,893	303,302
Other assets, net	14,096	12,920
Total assets	3,414,828	3,042,209
Current liabilities:
Accounts payable - Antero Resources	3,758	6,459
Accounts payable - third party	15,656	8,642
Accrued liabilities	88,258	106,006
Other current liabilities	215	209
Total current liabilities	107,887	121,316
Long-term liabilities:
Long-term debt	1,516,854	1,196,000
Contingent acquisition consideration	219,855	208,014
Asset retirement obligations	3,148
Other	2,522	410
Total liabilities	1,850,266	1,525,740
Partners' capital:
General partner	37,815	23,772
Total partners' capital	1,564,562	1,516,469
Total liabilities and partners' capital	3,414,828	3,042,209
Common Unitholders Public
Partners' capital:
Common unitholders	1,726,112	1,708,379
Total partners' capital	1,726,112	1,708,379
Common Unitholder Antero Resources
Partners' capital:
Common unitholders	(199,365)	(215,682)
Total partners' capital	$ (199,365)	$ (215,682)

Condensed Consolidated Balance Sheets (Parenthetical) - shares shares in Thousands	Sep. 30, 2018	Dec. 31, 2017
Common Unitholders Public
Common unitholders units issued	88,175	88,059
Common unitholders units outstanding	88,175	88,059
Common Unitholder Antero Resources
Common unitholders units issued	98,870	98,870
Common unitholders units outstanding	98,870	98,870

Condensed Consolidated Statements of Operations and Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue
Revenue	$ 266,205	$ 193,629	$ 746,188	$ 562,165
Gain on sale of assets - Antero Resources			583
Total revenue	266,205	193,629	746,771	562,165
Operating expenses:
Direct operating	81,475	63,030	224,354	162,892
General and administrative	15,018	14,316	44,967	43,562
Impairment of property and equipment	1,157		5,771
Depreciation	38,456	30,556	107,321	88,604
Accretion of contingent acquisition consideration	4,020	2,556	11,841	9,672
Accretion of asset retirement obligations	33		101
Total operating expenses	140,159	110,458	394,355	304,730
Operating income	126,046	83,171	352,416	257,435
Interest expense, net	(16,988)	(9,311)	(42,913)	(27,162)
Equity in earnings of unconsolidated affiliates	10,706	7,033	27,832	12,887
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
Net income per limited partner unit - basic and diluted	$ 0.44	$ 0.33
Net income per limited partner unit–basic	$ 0.44	$ 0.33	$ 1.27	$ 1.06
Weighted average limited partner units outstanding - basic	187,044	186,581	186,999	185,240
Weighted average limited partner units outstanding - diluted	187,502	187,145	187,342	185,728
Natural Gas, Gathering, Transportation, Marketing and Processing - Affiliate
Revenue
Revenue	$ 133,202	$ 100,518	$ 359,515	$ 290,675
Natural Gas Water Handling and Treatment - Affiliate
Revenue
Revenue	132,898	$ 93,111	386,018	271,226
Natural Gas, Gathering, Transportation, Marketing and Processing
Revenue
Revenue				$ 264
Natural Gas Water Handling and Treatment
Revenue
Revenue	$ 105		$ 655

Condensed Consolidated Statements of Operations and Comprehensive Income (Parenthetical) - 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-based compensation	$ 4,528	$ 7,199	$ 16,606	$ 20,436

Condensed Consolidated Statements of Partners' Capital - USD ($) $ in Thousands	Common Unitholders Public	Common Unitholder Antero Resources	Subordinated Unitholder Antero Resources	General Partner	Total
Balance at Dec. 31, 2016	$ 1,458,410	$ 26,820	$ (269,963)	$ 7,543	$ 1,222,810
Partner' Capital
Net income and comprehensive income	25,609	37,929		11,553	75,091
Distributions to unitholders	(19,606)	(30,484)		(7,543)	(57,633)
Conversion of subordinated units to common units		(269,963)	269,963
Equity-based compensation	2,149	4,137			6,286
Issuance of common units, net of offering costs	223,119				223,119
Balance at Mar. 31, 2017	1,689,681	(231,561)		11,553	1,469,673
Balance at Dec. 31, 2016	1,458,410	26,820	$ (269,963)	7,543	1,222,810
Partner' Capital
Net income and comprehensive income					243,160
Balance at Sep. 30, 2017	1,708,930	(193,611)		19,067	1,534,386
Balance at Mar. 31, 2017	1,689,681	(231,561)		11,553	1,469,673
Partner' Capital
Net income and comprehensive income	29,769	42,079		15,328	87,176
Distributions to unitholders	(23,167)	(32,661)		(11,553)	(67,381)
Equity-based compensation	2,432	4,519			6,951
Issuance of common units upon vesting of equity-based compensation awards, net of units withheld for income taxes	627	(1,559)			(932)
Issuance of common units, net of offering costs	23,466				23,466
Balance at Jun. 30, 2017	1,722,808	(219,183)		15,328	1,518,953
Partner' Capital
Net income and comprehensive income	25,996	35,830		19,067	80,893
Distributions to unitholders	(24,856)	(34,839)		(15,328)	(75,023)
Equity-based compensation	2,558	4,641			7,199
Sale of units held by Antero Resources to public	(19,940)	19,940
Issuance of common units, net of offering costs	2,364				2,364
Balance at Sep. 30, 2017	1,708,930	(193,611)		19,067	1,534,386
Balance at Dec. 31, 2017	1,708,379	(215,682)		23,772	1,516,469
Partner' Capital
Net income and comprehensive income	37,524	42,128		28,453	108,105
Distributions to unitholders	(32,143)	(36,088)		(23,772)	(92,003)
Equity-based compensation	2,354	3,857			6,211
Issuance of common units upon vesting of equity-based compensation awards, net of units withheld for income taxes	32	(50)			(18)
Other	(5)				(5)
Balance at Mar. 31, 2018	1,716,141	(205,835)		28,453	1,538,759
Balance at Dec. 31, 2017	1,708,379	(215,682)		23,772	1,516,469
Partner' Capital
Net income and comprehensive income					337,335
Balance at Sep. 30, 2018	1,726,112	(199,365)		37,815	1,564,562
Balance at Mar. 31, 2018	1,716,141	(205,835)		28,453	1,538,759
Partner' Capital
Net income and comprehensive income	35,965	40,356		33,145	109,466
Distributions to unitholders	(34,647)	(38,559)		(28,461)	(101,667)
Equity-based compensation	2,141	3,726			5,867
Issuance of common units upon vesting of equity-based compensation awards, net of units withheld for income taxes	2,707	(4,007)			(1,300)
Other	8				8
Balance at Jun. 30, 2018	1,722,315	(204,319)		33,137	1,551,133
Partner' Capital
Net income and comprehensive income	38,629	43,319		37,816	119,764
Distributions to unitholders	(36,614)	(41,031)		(33,138)	(110,783)
Equity-based compensation	1,556	2,972			4,528
Issuance of common units upon vesting of equity-based compensation awards, net of units withheld for income taxes	225	(306)			(81)
Other	1				1
Balance at Sep. 30, 2018	$ 1,726,112	$ (199,365)		$ 37,815	$ 1,564,562

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows provided by (used in) operating activities:
Net income	$ 337,335	$ 243,160
Adjustment to reconcile net income to net cash provided by operating activities:
Depreciation	107,321	88,604
Accretion of contingent acquisition consideration	11,841	9,672
Accretion of asset retirement obligations	101
Impairment of property and equipment	5,771
Equity-based compensation	16,606	20,436
Equity in earnings of unconsolidated affiliates	(27,832)	(12,887)
Distributions from unconsolidated affiliates	29,660	10,120
Amortization of deferred financing costs	2,083	1,906
Gain on sale of assets	(583)
Changes in assets and liabilities:
Accounts receivable – Antero Resources	(10,723)	(19,985)
Accounts receivable - third party	944	75
Prepaid expenses	(804)	(484)
Accounts payable – Antero Resources	(2,009)	857
Accounts payable - third party	4,221	1,181
Accrued liabilities	(2,530)	1,612
Net cash provided by operating activities	471,402	344,267
Cash flows used in investing activities:
Additions to gathering systems and facilities	(337,623)	(254,619)
Additions to water handling and treatment systems	(68,325)	(143,470)
Investments in unconsolidated affiliates	(91,419)	(216,776)
Proceeds from sale of assets	4,470
Change in other assets	(3,138)	(5,877)
Change in other liabilities	2,273
Net cash used in investing activities	(493,762)	(620,742)
Cash flows provided by (used in) financing activities:
Distributions to unitholders	(304,453)	(200,037)
Borrowings on bank credit facilities, net	320,000	217,000
Issuance of common units, net of offering costs		248,949
Employee tax withholding for settlement of equity compensation awards	(1,399)	(932)
Other	(151)	(52)
Net cash provided by financing activities	13,997	264,928
Net increase in cash and cash equivalents	(8,363)	(11,547)
Cash and cash equivalents, beginning of period	8,363	14,042
Cash and cash equivalents, end of period		2,495
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	53,576	42,530
Increase (decrease) in accrued capital expenditures and accounts payable for property and equipment	$ (13,115)	$ 2,936

Business and Organization	9 Months Ended
Business and Organization	Sep. 30, 2018
Business and Organization
Business and Organization	(1) Business and Organization (a) Overview Antero Midstream Partners LP (the “Partnership”) is a growth-oriented master limited partnership formed by Antero Resources Corporation (“Antero Resources”) to own, operate and develop midstream energy infrastructure primarily to service Antero Resources’ increasing production and completion activity in the Appalachian Basin’s Marcellus Shale and Utica Shale located in West Virginia and Ohio. The Partnership’s assets consist of gathering pipelines, compressor stations, interests in processing and fractionation plants, and water handling and treatment assets, through which the Partnership and its affiliates provide midstream services to Antero Resources under long-term, fixed-fee contracts. The Partnership’s unaudited condensed consolidated financial statements as of September 30, 2018 include the accounts of the Partnership and its 100% owned operating subsidiaries: Antero Midstream LLC, Antero Water LLC (“Antero Water”), Antero Treatment LLC (“Antero Treatment”), and Antero Midstream Finance Corporation (“Finance Corp”), all of which are entities under common control. The Partnership also has a 15% equity interest in the gathering system of Stonewall Gas Gathering LLC (“Stonewall”) and a 50% equity interest in a joint venture to develop processing and fractionation assets (the “Joint Venture”) with MarkWest Energy Partners, L.P. (“MarkWest”). See Note 13—Equity Method Investments. The Partnership’s financial statements are consolidated with the financial statements of Antero Resources (NYSE: AR), our primary beneficiary, for financial reporting purposes. (b) Simplification Agreement On October 9, 2018, the Partnership, Antero Midstream GP LP (“AMGP”) 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 the Partnership, with the Partnership surviving the merger as an indirect, wholly owned subsidiary of New AM (the “Merger”) and (3) all the issued and outstanding Series B Units representing limited liability company interests of Antero IDR Holdings LLC (“IDR Holdings”), a subsidiary of AMGP and the holder of all of the Partnership’s incentive distribution rights, will be exchanged for an aggregate of approximately 17.35 million shares of New AM’s common stock (the “Series B Exchange”). 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, the Partnership 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. If the Transactions are completed, (1) each holder of the Partnership’s common units other than Antero Resources (the “AM Public Unitholders”), will be entitled to receive, at its election, one of (i) $3.415 in cash without interest and 1.6350 validly issued, fully paid, nonassessable shares of New AM’s common stock for each of the Partnership’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 the Partnership’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 the Partnership’s common units held (the “Public Cash Consideration”); and (2) in exchange for each of the Partnership’s common units held, Antero Resources will be entitled, subject to certain adjustments (as described below), to receive $3.00 in cash without interest and 1.6023 validly issued, fully paid, nonassessable shares of New AM’s common stock for each of the Partnership’s common units held by Antero Resources (the “AR Mixed Consideration”). The aggregate cash consideration to be paid to Antero Resources and the AM Public Unitholders will be fixed at an amount equal to the aggregate amount of cash that would have been paid and issued if all AM Public Unitholders received $3.415 in cash per common unit and Antero Resources received $3.00 in cash per common unit, which is approximately $598 million (the “Available Cash”). If the Available Cash exceeds the cash consideration elected to be received by the AM Public Unitholders, Antero Resources may elect to increase the total amount of cash consideration to be received as a part of the AR Mixed Consideration up to an amount equal to the excess and the amount of shares it will receive will be reduced accordingly based on the AMGP VWAP. In addition, the consideration to be received each AM Public Unitholder 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 had received the Public Mixed Consideration and Antero Resources received the AR Mixed Consideration. The Merger should be a taxable event for the Partnership’s unitholders, even if a unitholder receives no cash consideration other than cash received in lieu of fractional shares, if any, in the Merger. The amount and character of gain or loss recognized by each unitholder in the Merger will vary depending on such unitholder’s particular situation, including the value of the shares of New AM’s common stock, if any, received by such unitholder, the amount of any cash received by such unitholder, the adjusted tax basis of such unitholder’s common units (and any changes to such tax basis as a result of our allocations of income, gain, loss and deduction to such unitholder for the taxable year that includes the Merger), and the amount of any suspended passive losses that may be available to such unitholder to offset a portion of the gain recognized by such unitholder in connection with the Merger. 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 the Partnership’s common unitholders and AMGP’s shareholders. AMGP and the Partnership expect to fund the cash portion of the merger consideration with borrowings under the Partnership’s revolving credit facility. The revolving credit facility was amended on October 31, 2018 to increase lender commitments from $1.5 billion to $2.0 billion. Also on October 9, 2018, in connection with the entry into the Simplification Agreement, (1) the Partnership 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 Stockholders”) 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 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 U.S. Securities and Exchange Commission (the “SEC”) applicable to interim financial information and should be read in the context of the December 31, 2017 consolidated financial statements and notes thereto for a more complete understanding of the Partnership’s operations, financial position, and accounting policies. The December 31, 2017 consolidated financial statements have been filed with the SEC in the Partnership’s 2017 Form 10-K.

These unaudited condensed consolidated financial statements of the Partnership 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, these unaudited condensed consolidated financial statements include all adjustments (consisting of normal and recurring accruals) considered necessary for a fair presentation of the Partnership’s financial position as of December 31, 2017 and September 30, 2018, and the results of our operations for three and nine months ended September 30, 2017 and 2018, and its cash flows for the nine months ended September 30, 2017 and 2018. The Partnership has no items of other comprehensive income; therefore, its net income is equal to its comprehensive income.

Certain costs of doing business incurred by Antero Resources on the Partnership’s behalf have been reflected in the accompanying unaudited condensed consolidated financial statements. These costs include general and administrative expenses attributed to the Partnership by Antero Resources in exchange for:

·

business services, such as payroll, accounts payable and facilities management;

·

corporate services, such as finance and accounting, legal, human resources, investor relations and public and regulatory policy; and

·

employee compensation, including equity‑based compensation.

Transactions between the Partnership and Antero Resources have been identified in the unaudited condensed consolidated financial statements (see Note 3—Transactions with Affiliates).

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 15 – Subsequent Events.

(b) Revenue Recognition

The Partnership provides gathering and compression and water handling and treatment services under fee-based contracts primarily based on throughput or at cost plus a margin. Under these arrangements, the Partnership receives fees for gathering oil and gas products, compression services, and water handling and treatment services. The revenue the Partnership earns from these arrangements is directly related to (1) in the case of natural gas gathering and compression, the volumes of metered natural gas that it gathers, compresses, and delivers to natural gas compression sites or other transmission delivery points, (2) in the case of oil gathering, the volumes of metered oil that it gathers and delivers to other transmission delivery points, (3) in the case of fresh water services, the quantities of fresh water delivered to its customers for use in their well completion operations, (4) in the case of wastewater treatment services performed by the Partnership, the quantities of wastewater treated for our customers, or (5) in the case of flowback and produced water services provided by third parties, the third party costs the Partnership incurs plus 3%. The Partnership recognizes revenue when it satisfies a performance obligation by delivering a service to a customer.

(c)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 revenues, expenses, assets, liabilities, and the disclosure of contingent assets and liabilities. Items subject to estimates and assumptions include the useful lives of property and equipment, as well as the valuation of accrued liabilities, among others. Although management believes these estimates are reasonable, actual results could differ from these estimates.

(d)Cash and Cash Equivalents

The Partnership considers all liquid investments purchased with an initial maturity of three months or less to be cash equivalents. The carrying value of cash and cash equivalents approximates fair value due to the short-term nature of these instruments. From time to time, the Partnership may be in the position of a “book overdraft” in which outstanding checks exceed cash and cash equivalents. The Partnership classifies book overdrafts within accounts payable within its unaudited condensed consolidated balance sheets, and classifies the change in accounts payable associated with book overdrafts as an operating activity within its unaudited condensed consolidated statements of cash flows. The Partnership classified $2.8 million of book overdrafts within accounts payable as of September 30, 2018.

(e)Property and Equipment

Property and equipment primarily consists of gathering pipelines, compressor stations, fresh water delivery pipelines and facilities, and the wastewater treatment facility and related landfill used for the disposal of waste therefrom, stated at historical cost less accumulated depreciation and amortization. The Partnership capitalizes construction-related direct labor and material costs. The Partnership also capitalized interest on capital costs during the construction phase of the wastewater treatment facility, which was placed in service in May 2018. The Partnership capitalized interest of $3 million for the three months ended September 30, 2017 and no interest for the three months ended September 30, 2018. For the nine months ended September 30, 2017 and 2018, the Partnership capitalized interest of $9 million and $4 million, respectively. Net operating expenses incurred during wastewater treatment facility commissioning were capitalized. Due to delays in reaching contractual treatment capacity of the wastewater treatment facility, the Partnership has and continues to accrue for liquidated damages from the vendor. At September 30, 2018, the Partnership had accrued $16 million for liquidated damages as a receivable and reduction in cost of the facility. Maintenance and repair costs are expensed as incurred.

Depreciation of property and equipment is computed using the straight-line method over the estimated useful lives and salvage values of assets. The depreciation of fixed assets recorded under capital lease agreements is included in depreciation expense. Uncertainties that may impact these estimates of useful lives include, among others, changes in laws and regulations relating to environmental matters, including air and water quality, restoration and abandonment requirements, economic conditions, and supply and demand for our services in the areas in which we operate. When assets are placed into service, management makes estimates with respect to useful lives and salvage values that management believes are reasonable. However, subsequent events could cause a change in estimates, thereby impacting future depreciation amounts.

Amortization of landfill airspace consists of the amortization of landfill capital costs, including those that have been incurred and capitalized and estimated future costs for landfill development and construction, as well as the amortization of asset retirement costs arising from landfill final capping, closure, and post-closure obligations. Amortization expense is recorded on a units-of-consumption basis, applying cost as a rate per-cubic yard. The rate per-cubic yard is calculated by dividing each component of the amortizable basis of the landfill by the number of cubic yards needed to fill the corresponding asset’s airspace. Landfill capital costs and closure and post-closure asset retirement costs are generally incurred to support the operation of the landfill over its entire operating life and are, therefore, amortized on a per-cubic yard basis using a landfill’s total airspace capacity. Estimates of disposal capacity and future development costs are created using input from independent engineers and internal technical teams and are reviewed at least annually. However, future events could cause a change in estimates, thereby impacting future amortization amounts.

Our investment in property and equipment as of the dates presented was as follows (in thousands):


	Estimated	December 31,		September 30,
	useful lives	2017		2018
Land	n/a	$	15,382		18,649
Gathering systems and facilities	20 years		1,781,386		2,075,542
Fresh water permanent buried pipelines and equipment	20 years		472,810		510,374
Wastewater treatment facility	30 years		—		299,567
Fresh water surface pipelines and equipment	5 years		46,139		61,865
Landfill	n/a(1)		—		58,318
Heavy trucks and equipment	5 years		—		4,831
Above ground storage tanks	10 years		4,301		4,824
Construction-in-progress(2)	n/a		654,904		316,545
Total property and equipment			2,974,922		3,350,515
Less accumulated depreciation			(369,320)		(476,641)
Property and equipment, net		$	2,605,602		2,873,874

(1) Amortization of landfill costs is recorded over the life of the landfill on a units-of-consumption basis.

(2) As of December 31, 2017, construction-in-progress included $355 million for the construction of the wastewater treatment facility and landfill, which was placed in service in May 2018.

(f)Asset Retirement Obligations

In December 2017, the Partnership completed the construction of a landfill site to be used for the disposal of waste from its wastewater treatment facility. The landfill began accepting waste in January 2018. The Partnership’s asset retirement obligations relate to its obligation to close, maintain, and monitor landfill cells and support facilities. After the entire landfill has reached capacity and is certified closed, the Partnership must continue to maintain and monitor the landfill for a post-closure period, which generally extends for 30 years. The Partnership records the fair value of its landfill retirement obligations as a liability in the period in which the regulatory obligation to retire a specific asset is triggered. For the Partnership’s individual landfill cells, the required closure and post-closure obligations under the terms of its permits and its intended operation of the landfill cell are triggered and recorded when the cell is placed into service and waste is initially disposed in the landfill cell. The fair value is based on the total estimated costs to close the landfill cell and perform post-closure activities once the landfill cell has reached capacity and is no longer accepting waste. Retirement obligations are increased each year to reflect the passage of time by accreting the balance at the weighted average credit-adjusted risk-free rate that is used to calculate the recorded liability, with accretion charged to direct costs. Actual cash expenditures to perform closure and post-closure activities reduce the retirement obligation liabilities as incurred. After initial measurement, asset retirement obligations are adjusted at the end of each period to reflect changes, if any, in the estimated future cash flows underlying the obligation. Landfill retirement assets are capitalized as the related retirement obligations are incurred, and are amortized on a units-of-consumption basis as the disposal capacity is consumed.

The Partnership is under no legal obligations, neither contractually nor under the doctrine of promissory estoppel, to restore or dismantle its gathering pipelines, compressor stations, water delivery pipelines and facilities and wastewater treatment facility upon abandonment. The Partnership’s gathering pipelines, compressor stations, fresh water delivery pipelines and facilities and wastewater treatment facility have an indeterminate life, if properly maintained. Accordingly, the Partnership is not able to make a reasonable estimate of when future dismantlement and removal dates of its pipelines, compressor stations and facilities will occur. It has been determined by the Partnership’s operational management team that abandoning all other ancillary equipment, outside of the assets stated above, would require minimal costs.

(g)Equity‑Based Compensation

The Partnership’s unaudited condensed consolidated financial statements reflect various equity-based compensation awards granted by Antero Resources, as well as compensation expense associated with the Partnership’s plan. These awards include profits interests awards, restricted stock, stock options, restricted units, and phantom units. In each period, the Partnership recognizes expense in an amount allocated from Antero Resources, with the offset included in partners’ capital. See Note 3—Transactions with Affiliates for additional information regarding Antero Resources’ allocation of expenses to the Partnership.

Under the Antero Midstream Partners LP Long-Term Incentive Plan (“Midstream LTIP”), certain non-employee directors of the general partner and certain officers, employees and consultants the general partner and its affiliates are eligible to receive awards representing equity interests in the Partnership. An aggregate of 10,000,000 common units may be delivered pursuant to awards under the Midstream LTIP, subject to customary adjustments. For accounting purposes, these units are treated as if they are distributed from the Partnership to Antero Resources. Antero Resources recognizes compensation expense for the units awarded to its employees and a portion of that expense is allocated to the Partnership. See Note 8—Equity-Based Compensation.

(h)Income Taxes

Our unaudited condensed consolidated financial statements do not include a provision for income taxes as we are treated as a partnership for federal and state income tax purposes, with each partner being separately taxed on its distributive share of our items of income, gain, loss, or deduction.

(i)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 the Partnership estimates 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. The Partnership’s 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, that are observable for the asset or liability, either directly or indirectly.

The carrying values on the balance sheet of the Partnership’s cash and cash equivalents, accounts receivable—Antero Resources, accounts receivable—third party, prepaid expenses, other assets, accounts payable—Antero Resources, accounts payable, accrued liabilities, other current liabilities, other liabilities and the revolving credit facility approximate fair values due to their short-term maturities.

(j)Investments in Unconsolidated Affiliates

The Partnership uses the equity method to account for its investments in companies if the investment provides the Partnership with the ability to exercise significant influence over, but not control, the operating and financial policies of the investee. The Partnership’s consolidated net income includes the Partnership’s proportionate share of the net income or loss of such companies. The Partnership’s judgment regarding the level of influence over each equity method investee includes considering key factors such as the Partnership’s ownership interest, representation on the board of directors and participation in policy-making decisions of the investee and material intercompany transactions. See Note 13–Equity Method Investments.

(k)Adoption of New Accounting Principle

On May 28, 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU replaces most existing revenue recognition guidance in GAAP when it became effective and was incorporated into GAAP as Accounting Standards Codification (“ASC”) Topic 606. The new standard became effective for us on January 1, 2018. The standard permits the use of either the full retrospective or modified restrospective transition method. The Partnership elected the modified retrospective transition method. The adoption of ASU 2014-09 did not have a material impact on our financial results. See Note 4—Revenue for the Partnership’s required disclosures under ASC 606.

(l)Recently Issued Accounting Standard

On February 25, 2016, the FASB issued ASU No. 2016-02, Leases, which requires all leasing arrangements to be presented in the balance sheet as liabilities along with a corresponding asset. The ASU will replace most existing leases guidance in GAAP when it becomes effective. The new standard becomes effective for the Partnership on January 1, 2019. Although early application is permitted, the Partnership does not plan to early adopt the ASU. The standard requires the use of the modified retrospective transition method. The Partnership is evaluating the effect that ASU 2016-02 will have on its consolidated financial statements and related disclosures. The Partnership is evaluating the standard’s applicability to its various contractual arrangements with Antero Resources, and the Partnership believes that the application of the ASU to its contractual arrangements with Antero Resources could be subject to differing interpretations. The accounting treatment for these arrangements under the ASU could include (i) the recognition of our Antero contracts as leases under the ASU, (ii) characterization of our servicing revenues from gathering, compression, and water handling and treatment as revenues from leasing or financing, and (iii) derecognition of assets on our balance sheet that are used to provide services under contracts containing variable payment terms. Other interpretations and applications of the standard may be possible, including no material changes to the accounting for these contractual arrangements. The Partnership is updating its accounting policies and internal controls that would be impacted by the new guidance and implementing information technology tools to assist with its ongoing lease data collection and analysis to ensure readiness for adoption in the first quarter of 2019. The Partnership continues to monitor relevant industry guidance regarding implementation of ASU 2016-02 and will adjust its implementation of the standard as necessary. The Partnership believes that adoption of the standard will not impact its operational strategies, growth prospects, or cash flow.

Transactions with Affiliates	9 Months Ended
Transactions with Affiliates	Sep. 30, 2018
Transactions with Affiliates
Transactions with Affiliates	(3) Transactions with Affiliates (a)Revenues All revenues earned in the three and nine months ended September 30, 2017 and 2018, except revenues earned from third parties, were earned from Antero Resources, under various agreements for gathering and compression and water handling and treatment services. (b)Accounts receivable—Antero Resources and Accounts payable—Antero Resources Accounts receivable—Antero Resources represents amounts due from Antero Resources, primarily related to gathering and compression services and water handling and treatment services. Accounts payable—Antero Resources represents amounts due to Antero Resources for general and administrative and other costs. (c)Allocation of Costs The employees supporting the Partnership’s operations are employees of Antero Resources. Direct operating expense includes allocated costs of $2.6 million and $1.8 million during the three months ended September 30, 2017 and 2018, and $5.0 million and $5.3 million during the nine months ended September 30, 2017 and 2018 respectively, related to labor charges for Antero Resources employees associated with the operation of our gathering lines, compressor stations, and water handling and treatment assets. General and administrative expense includes allocated costs of $13.0 million and $12.8 million during the three months ended September 30, 2017 and 2018, and $39.8 million and $39.9 million during the nine months ended September 30, 2017 and 2018, respectively. These costs relate to: (i) various business services, including payroll processing, accounts payable processing and facilities management, (ii) various corporate services, including legal, accounting, treasury, information technology and human resources and (iii) compensation, including equity-based compensation (see Note 8—Equity-Based Compensation for more information). These expenses are charged or allocated to the Partnership based on the nature of the expenses and are allocated based on a combination of the Partnership’s proportionate share of gross property and equipment, capital expenditures and labor costs, as applicable. The Partnership reimburses Antero Resources directly for all general and administrative costs allocated to it, with the exception of noncash equity compensation allocated to the Partnership for awards issued under the Antero Resources long-term incentive plan or the Midstream LTIP.

Revenue

9 Months Ended

Sep. 30, 2018

Revenue

Revenue

(4) Revenue

(a) Revenue from Contracts with Customers

All of the Partnership’s revenues are derived from service contracts with customers, and are recognized when the Partnership satisfies a performance obligation by delivering a service to a customer. Antero Resources is the Partnership’s most significant customer, and the Partnership expects to derive substantially all of its revenues from Antero Resources for the foreseeable future. The following sets forth the nature, timing of satisfaction of performance obligations, and significant payment terms of the Partnership’s contracts with Antero Resources.

Gathering and Compression Agreement

Antero Resources has dedicated all of its current and future acreage in West Virginia, Ohio and Pennsylvania to the Partnership for gathering and compression services except for acreage attributable to existing third-party commitments. The Partnership also has an option to gather and compress natural gas produced by Antero Resources on any acreage it acquires in the future outside of West Virginia, Ohio and Pennsylvania on the same terms and conditions. Under the gathering and compression agreement, the Partnership receives a low pressure gathering fee of $0.30 per Mcf, a high pressure gathering fee of $0.18 per Mcf, and a compression fee of $0.18 per Mcf, in each case subject to CPI-based adjustments since 2014. In addition, the agreement stipulates that the Partnership receives a reimbursement for the actual cost of electricity used at its compressor stations.

The Partnership satisfies its performance obligations and recognizes revenue when low pressure volumes are delivered to a compressor station, high pressure volumes are delivered to a processing plant or transmission pipeline, and compression volumes are delivered to a high pressure line. The Partnership invoices the customer the month after each service is performed, and payment is due in the same month.

Water Handling and Treatment Agreement

In connection with Antero Resources’ contribution of Antero Water and certain wastewater treatment assets to the Partnership in September 2015 (the “Water Acquisition”), the Partnership entered into a water services agreement with Antero Resources whereby the Partnership agreed to provide certain water handling and treatment services to Antero Resources within an area of dedication in defined service areas in Ohio and West Virginia. Antero Resources agreed to pay the Partnership for all water handling and treatment services provided by the Partnership in accordance with the terms of the water services agreement. The initial term of the water services agreement is 20 years from September 23, 2015 and from year to year thereafter until terminated by either party. Under the agreement, the Partnership receives a fixed fee of $3.685 per barrel in West Virginia and $3.635 per barrel in Ohio and all other locations for fresh water deliveries by pipeline directly to the well site, as well as $3.116 per barrel for fresh water delivered by truck to high-rate transfer facilities. All of these fees have been subject to annual CPI adjustments since the inception of the agreement in 2015. Antero Resources also agreed to pay the Partnership a fixed fee of $4.00 per barrel for wastewater treatment at the advanced wastewater treatment complex, in each case subject to annual CPI-based adjustments and additional fees based on certain costs.

Under the water services agreement, the Partnership may also contract with third parties to provide water services to Antero Resources. Antero Resources reimburses the Partnership for third party out-of-pocket costs plus a 3% markup.

The Partnership satisfies its performance obligations and recognizes revenue when the fresh water volumes have been delivered to the hydration unit of a specified well pad and the wastewater volumes have been delivered to the Partnership’s wastewater treatment facility. The Partnership invoices the customer the month after water services are performed, and payment is due in the same month. For services contracted through third party providers, the Partnership’s performance obligation is satisfied when the service to be performed by the third party provider has been completed. The Partnership invoices the customer after the third party provider billing is received, and payment is due in the same month.

Minimum Volume Commitments

Both the gathering and compression and water handling and treatment agreements include certain minimum volume commitment provisions, which are intended to support the stability of our cash flows. If and to the extent Antero Resources requests that the Partnership constructs new high pressure lines and compressor stations, the gathering and compression agreement contains minimum volume commitments that require Antero Resources to utilize or pay for 75% and 70%, respectively, of the capacity of such new construction for 10 years. Antero Resources also committed to pay a fee on a minimum volume of fresh water deliveries in calendar years 2016 through 2019. Antero Resources is obligated to pay a minimum volume fee to the Partnership in the event the aggregate volume of fresh water delivered to Antero Resources under the water services agreement is less than 120,000 barrels per day in 2018 and 2019. The Partnership recognizes revenue related to these minimum volume commitments at the time it is determined that the volumes will not be consumed by Antero Resources, and the amount of the shortfall is known.

Minimum revenue amounts under the minimum volume commitments are as follows (in thousands):


	Remainder		Year Ended December 31,
	of 2018		2019	2020	2021	2022	2023	Thereafter	Total
Minimum revenue under the Gathering and Compression Agreement	$	24,351	158,725	159,160	158,725	158,725	158,725	498,917	1,317,328
Minimum revenue under the Water Handling and Treatment Agreement		—	165,564	—	—	—	—	—	165,564
Total	$	24,351	324,289	159,160	158,725	158,725	158,725	498,917	1,482,892

(b) Disaggregation of Revenue

In the following table, revenue is disaggregated by type of service and type of fee (in thousands). The table also identifies the reportable segment to which the disaggregated revenues relate. For more information on reportable segments, see Note 14—Reportable Segments.


	Three Months Ended September 30,				Nine Months Ended September 30,				Segment to which
	2017		2018		2017		2018		revenues relate
Revenue from contracts with customers
Type of service
Gathering—low pressure	$	46,153		63,884	$	141,783		174,539	Gathering and Processing
Gathering—high pressure		33,365		38,409		90,095		102,714	Gathering and Processing
Compression		21,000		30,909		58,997		82,262	Gathering and Processing
Condensate gathering		—		—		64		—	Gathering and Processing
Fresh water delivery		48,352		68,144		156,635		222,367	Water Handling and Treatment
Wastewater treatment		—		5,260		—		8,431	Water Handling and Treatment
Other fluid handling		44,759		59,599		114,591		155,875	Water Handling and Treatment
Total	$	193,629		266,205	$	562,165		746,188
Type of contract
Fixed Fee	$	100,518		133,202	$	290,939		359,515	Gathering and Processing
Fixed Fee		48,352		73,404		156,635		230,798	Water Handling and Treatment
Cost plus 3%		44,759		59,599		114,591		155,875	Water Handling and Treatment
Total	$	193,629		266,205	$	562,165		746,188

Gain on sale of assets		—		—		—		583	Gathering and Processing
Total revenue	$	193,629		266,205		562,165		746,771

(c) Transaction Price Allocated to Remaining Performance Obligations

The majority of the Partnership’s service contracts have a term greater than one year. As such, the Partnership has utilized the practical expedient in ASC 606, which states that a company is not required to disclose the transaction price allocated to remaining performance obligations if the variable consideration is allocated entirely to a wholly unsatisfied performance obligation. Under the Partnership’s service contracts, each unit of product delivered to the customer represents a separate performance obligation; therefore, future volumes are wholly unsatisfied and disclosure of the transaction price allocated to remaining performance obligations is not required.

The remainder of our service contracts, which relate to contracts with third parties, are short-term in nature with a contract term of one year or less. The Partnership has utilized an additional practical expedient in ASC 606, which exempts the Partnership from disclosure of the transaction price allocated to remaining performance obligations if the performance obligation is part of a contract that has an original expected duration of one year or less.

(d) Contract Balances

Under the Partnership’s service contracts, the Partnership invoices customers after its performance obligations have been satisfied, at which point payment is unconditional. Accordingly, the Partnership’s service contracts do not give rise to contract assets or liabilities under ASC 606. At December 31, 2017 and September 30, 2018, the Partnership’s receivables with customers were $110 million and $116 million, respectively.

Long-term Debt

9 Months Ended

Sep. 30, 2018

Long-term Debt.

Long-term Debt

(5)Long-Term Debt

Long-term debt was as follows at December 31, 2017 and September 30, 2018 (in thousands):


	December 31, 2017		September 30, 2018
Credit Facility (a)	$	555,000		875,000
5.375% senior notes due 2024 (b)		650,000		650,000
Net unamortized debt issuance costs		(9,000)		(8,146)
Total long-term debt	$	1,196,000		1,516,854

(a) Revolving Credit Facility

On October 26, 2017, the Partnership entered into an amended and restated senior revolving credit facility (our “Credit Facility” or “revolving credit facility”). The Credit Facility provides for fall away covenants and lower interest rates that are triggered if and when the Partnership elects to enter into an Investment Grade Period, as described below.

Lender commitments under the Credit Facility are $1.5 billion and the maturity date of the Credit Facility is October 26, 2022. Under the Credit Facility, “Investment Grade Period” is a period that, as long as no event of default has occurred and the Partnership is in pro forma compliance with the financial covenants under the Credit Facility, commences when the Partnership elects to give notice to the Administrative Agent that the Partnership has received at least one of either (i) a BBB- or better rating from Standard and Poor’s or (ii) a Baa3 or better from Moody’s (provided that the non-investment grade rating from the other rating agency is at least either Ba1 if Moody’s or BB+ if Standard and Poor’s (an “Investment Grade Rating”)). An Investment Grade Period can end at the Partnership’s election.

During a period that is not an Investment Grade Period, the Credit Facility is ratably secured by mortgages on substantially all of the Partnership’s properties, including the properties of its subsidiaries, and guarantees from its subsidiaries. During an Investment Grade Period, the liens securing the obligations thereunder shall be automatically released (subject to the provisions of the Credit Facility).

The revolving credit facility contains certain covenants including restrictions on indebtedness, and requirements with respect to leverage and interest coverage ratios; provided, however, that during an Investment Grade Period, such covenants become less restrictive on the Partnership. The revolving credit facility permits distributions to the holders of the Partnership’s equity interests in accordance with the cash distribution policy adopted by the board of directors of the general partner in connection with the Partnership’s initial public offering, provided that no event of default exists or would be caused thereby, and only to the extent permitted by our organizational documents. The Partnership was in compliance with all of the financial covenants under the Credit Facility as of December 31, 2017 and September 30, 2018.

Principal amounts borrowed are payable on the maturity date with such borrowings bearing interest that is payable quarterly or, in the case of Eurodollar Rate Loans, at the end of the applicable interest period if shorter than six months. Interest is payable at a variable rate based on LIBOR or the base rate, determined by election at the time of borrowing, plus an applicable margin rate. Interest at the time of borrowing is determined with reference to (i) during any period that is not an Investment Grade Period, the Partnership’s then-current leverage ratio and (ii) during an Investment Grade Period, with reference to the rating given to the Partnership by Moody’s or Standard and Poor’s. During any period that is not an Investment Grade Period, the applicable margin rates range from 25 basis points to 225 basis points. During an Investment Grade Period, the applicable margin rates range from 12.5 basis points to 200 basis points. Commitment fees on the unused portion of the revolving credit facility are due quarterly at rates ranging from 0.25% to 0.375% based on the leverage ratio, during a period that is not an Investment Grade Period, and 0.175% to 0.375% based on the Partnership’s rating during an Investment Grade Period.

At December 31, 2017 and September 30, 2018, the Partnership had borrowings under the Credit Facility of $555 million and $875 million, respectively, with a weighted average interest rate of 2.81% and 3.39%, respectively. No letters of credit were outstanding at December 31, 2017 or September 30, 2018 under the Credit Facility.

(b) 5.375% Senior Notes Due 2024

On September 13, 2016, the Partnership and its wholly-owned subsidiary, Finance Corp, as co-issuers, issued $650 million in aggregate principal amount of 5.375% senior notes due September 15, 2024 (the “2024 Notes”) at par. The 2024 Notes are unsecured and effectively subordinated to the revolving credit facility to the extent of the value of the collateral securing the revolving credit facility. The 2024 Notes are fully and unconditionally guaranteed on a joint and several senior unsecured basis by the Partnership’s wholly-owned subsidiaries (other than Finance Corp) and certain of its future restricted subsidiaries. Interest on the 2024 Notes is payable on March 15 and September 15 of each year. The Partnership may redeem all or part of the 2024 Notes at any time on or after September 15, 2019 at redemption prices ranging from 104.031% on or after September 15, 2019 to 100.00% on or after September 15, 2022. In addition, prior to September 15, 2019, the Partnership may redeem up to 35% of the aggregate principal amount of the 2024 Notes with an amount of cash not greater than the net cash proceeds of certain equity offerings, if certain conditions are met, at a redemption price of 105.375% of the principal amount of the 2024 Notes, plus accrued and unpaid interest. At any time prior to September 15, 2019, the Partnership may also redeem the 2024 Notes, in whole or in part, at a price equal to 100% of the principal amount of the 2024 Notes plus a “make-whole” premium and accrued and unpaid interest. If the Partnership undergoes a change of control, the holders of the 2024 Notes will have the right to require the Partnership to repurchase all or a portion of the notes at a price equal to 101% of the principal amount of the 2024 Notes, plus accrued and unpaid interest.

Accrued Liabilities

9 Months Ended

Sep. 30, 2018

Accrued Liabilities

Accrued Liabilities

(6) Accrued Liabilities

Accrued liabilities as of December 31, 2017 and September 30, 2018 consisted of the following items (in thousands):


	December 31,		September 30,
	2017		2018
Capital expenditures	$	63,286		48,067
Operating expenses		29,905		35,607
Interest expense		10,508		1,988
Other		2,307		2,596
Total accrued liabilities	$	106,006		88,258

Asset Retirement Obligations

9 Months Ended

Sep. 30, 2018

Asset Retirement Obligations

Asset Retirement Obligations

(7) Asset Retirement Obligations

The following is a reconciliation of our asset retirement obligations for the period shown below (in thousands):


Asset retirement obligations—December 31, 2017	$	—
Obligations incurred		3,047
Accretion expense		101
Asset retirement obligations—September 30, 2018	$	3,148

Equity-Based Compensation

9 Months Ended

Sep. 30, 2018

Equity-Based Compensation

Equity-Based Compensation

(8)Equity-Based Compensation

The Partnership’s general and administrative expenses include equity-based compensation costs allocated to it by Antero Resources for grants made pursuant to Antero Resources’ long‑term incentive plan and the Midstream LTIP. Equity‑based compensation expense allocated to the Partnership was $7.2 million and $4.5 million for the three months ended September 30, 2017 and 2018, respectively, and $20.4 million and $16.6 million for the nine months ended September 30, 2017 and 2018, respectively. These expenses were allocated to the Partnership based on its proportionate share of Antero Resources’ labor costs. Antero Resources has unamortized expense totaling approximately $79 million as of September 30, 2018 related to its various equity-based compensation plans, which includes the Midstream LTIP. A portion of this will be allocated to the Partnership as it is amortized over the remaining service period of the related awards. The Partnership does not reimburse Antero Resources for noncash equity compensation allocated to it for awards issued under the Antero Resources long-term incentive plan or the Midstream LTIP.

Midstream LTIP

The Partnership’s general partner manages its operations and activities, and Antero Resources employs the personnel who provide support to the Partnership’s operations. The general partner has adopted the Midstream LTIP, pursuant to which non‑employee directors of the general partner and certain officers, employees and consultants of the general partner and its affiliates are eligible to receive awards representing limited partner interests in the Partnership. An aggregate of 10,000,000 common units may be delivered pursuant to awards under the Midstream LTIP, subject to customary adjustments. A total of 7,752,232 common units are available for future grant under the Midstream LTIP as of September 30, 2018. Restricted units and phantom units granted under the Midstream LTIP vest subject to the satisfaction of service requirements, upon the completion of which common units in the Partnership are delivered to the holder of the restricted units or phantom units. Phantom units also contain distribution equivalent rights, which entitle the holder of vested common units to receive a “catch up” payment equal to common unit distributions paid during the vesting period of the phantom unit award. Compensation related to each restricted unit and phantom unit award is recognized on a straight-line basis over the requisite service period of the entire award. The grant date fair values of these awards are determined based on the closing price of the Partnership’s common units on the date of grant. These units are accounted for as if they are distributed by the Partnership to Antero Resources. Antero Resources recognizes compensation expense for the units awarded and a portion of that expense is allocated to the Partnership. Antero Resources allocates equity-based compensation expense to the Partnership based on our proportionate share of Antero Resources’ labor costs. The Partnership’s portion of the equity-based compensation expense is included in general and administrative expenses, and recorded as a credit to the applicable classes of partners’ capital.

A summary of restricted unit and phantom unit awards activity during the nine months ended September 30, 2018 is as follows:


		Weighted average		Aggregate
	Number of	grant date		intrinsic value
	units	fair value		(in thousands)
Total awarded and unvested—December 31, 2017	1,042,963	$	28.69	$	30,288
Granted	247,692	$	25.84
Vested	(144,620)	$	30.17
Forfeited	(93,419)	$	28.64
Total awarded and unvested—September 30, 2018	1,052,616	$	28.15	$	30,168

Intrinsic values are based on the closing price of the Partnership’s common units on the referenced dates. Midstream LTIP unamortized expense of $16.3 million at September 30, 2018, is expected to be recognized over a weighted average period of approximately 2.5 years and the Partnership’s proportionate share will be allocated to it as it is recognized.

Partnership Equity and Distributions

9 Months Ended

Sep. 30, 2018

Partnership Equity and Distributions

Partnership Equity and Distributions

(9)Partnership Equity and Distributions

Our Minimum Quarterly Distribution

Our partnership agreement provides for a minimum quarterly distribution of $0.17 per unit for each quarter, or $0.68 per unit on an annualized basis.

If cash distributions to the Partnership’s unitholders exceed $0.1955 per common unit in any quarter, the Partnership’s unitholders and the holder of the Partnership’s incentive distribution rights (“IDRs”), will receive distributions according to the following percentage allocations:



	Marginal Percentage
Total Quarterly Distribution	Interest in Distributions
Target Amount	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	%

General Partner Interest

Our general partner owns a non-economic general partner interest in us, which does not entitle it to receive cash distributions. However, our general partner is under common control with the holder of the IDRs and may in the future own common units or other equity interests in us and would be entitled to receive distributions on any such interests.

Cash Distributions

Cash distributions to the Partnership’s unitholders have been as follows:


			Distributions
Quarter and Year	Record Date	Distribution Date	Common unitholders		Holder of IDRs		Total		Distributions per unit
Q4 2016	February 1, 2017	February 8, 2017	$	50,090		7,543		57,633	$	0.280
*	April 21, 2017	April 30, 2017		75		—		75		*
Q1 2017	May 3, 2017	May 10, 2017		55,753		11,553		67,306		0.300
Q2 2017	August 3, 2017	August 16, 2017		59,695		15,328		75,023		0.320
Q3 2017	November 1, 2017	November 16, 2017		63,454		19,067		82,521		0.340
*	November 12, 2017	November 17, 2017		1,392		—		1,392		*
	Total 2017		$	230,459		53,491		283,950

Q4 2017	February 1, 2018	February 13, 2018	$	68,231		23,772		92,003	$	0.365
*	April 15, 2018	April 20, 2018		263		—		263		*
Q1 2018	May 3, 2018	May 18, 2018		72,943		28,461		101,404		0.390
*	July 15, 2018	July 31, 2018		21		—		21		*
Q2 2018	August 2, 2018	August 17, 2018		77,624		33,138		110,762		0.415
	Total 2018		$	219,082		85,371		304,453

* Distribution equivalent rights on limited partner interests that vested under the Midstream LTIP.

Net Income Per Limited Partner Unit

9 Months Ended

Sep. 30, 2018

Net Income Per Limited Partner Unit

Net Income Per Limited Partner Unit

(10) Net Income Per Limited Partner Unit

The Partnership’s net income is attributed to the general partners and limited partners, in accordance with their respective ownership percentages, and when applicable, giving effect to incentive distributions paid to the holder of the incentive distribution rights. Basic and diluted net income per limited partner unit is calculated by dividing limited partners’ interest in net income, less incentive distributions, by the weighted average number of outstanding limited partner units during the period.

The Partnership computes earnings per unit using the two-class method for master limited partnerships. Under the two-class method, earnings per unit is calculated as if all of the earnings for the period were distributed under the terms of the partnership agreement, regardless of whether the general partner has discretion over the amount of distributions to be made in any particular period, whether those earnings would actually be distributed during a particular period from an economic or practical perspective, or whether the general partner has other legal or contractual limitations on its ability to pay distributions that would prevent it from distributing all of the earnings for a particular period.

The Partnership calculates net income available to limited partners based on the distributions pertaining to the current period’s net income. After adjusting for the appropriate period’s distributions, the remaining undistributed earnings or excess distributions over earnings, if any, are attributed in accordance with the contractual terms of the partnership agreement under the two-class method.

Basic earnings per unit is computed by dividing net earnings attributable to unitholders by the weighted average number of units outstanding during each period. Diluted net income per limited partner unit reflects the potential dilution that could occur if agreements to issue common units, such as awards under long-term incentive plans, were exercised, settled or converted into common units. When it is determined that potential common units resulting from an award should be included in the diluted net income per limited partner unit calculation, the impact is reflected by applying the treasury stock method. Earnings per common unit assuming dilution for the three months ended September 30, 2018 was calculated based on the diluted weighted average number of units outstanding of 187,501,733 including 457,795 dilutive units attributable to non-vested restricted unit and phantom unit awards. Earnings per common unit assuming dilution for the nine months ended September 30, 2018 was calculated based on the diluted weighted average number of units outstanding of 187,342,199, including 343,227 dilutive units attributable to non-vested restricted unit and phantom unit awards. For the three and nine months ended September 30, 2018 there were no non-vested phantom unit and restricted unit awards that were anti-dilutive and therefore excluded from the calculation of diluted earnings per unit.

The Partnership’s calculation of net income per limited partner unit for the periods indicated is as follows (in thousands, except per unit data):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2018		2017		2018
Net income	$	80,893		119,764	$	243,160		337,335
Less:
Net income attributable to incentive distribution rights		(19,067)		(37,816)		(45,948)		(99,414)
Limited partner interest in net income	$	61,826		81,948	$	197,212		237,921

Net income per limited partner unit–basic and diluted	$	0.33		0.44	$	1.06		1.27

Weighted average limited partner units outstanding–basic		186,581		187,044		185,240		186,999

Weighted average limited partner units outstanding–diluted		187,145		187,502		185,728		187,342

Sale of Common Units Under Equity Distribution Agreement	9 Months Ended
	Sep. 30, 2018
Sale of Common Units Under Equity Distribution Agreement
Sale of Common Units Under Equity Distribution Agreement	(11) Sale of Common Units Under Equity Distribution Agreement During the third quarter of 2016, the Partnership entered into an Equity Distribution Agreement (the “Distribution Agreement”), pursuant to which the Partnership may sell, from time to time through brokers acting as its sales agents, common units representing limited partner interests having an aggregate offering price of up to $250 million. The program is registered with the SEC on an effective registration statement on Form S-3. Sales of the common units may be made by means of ordinary brokers’ transactions on the New York Stock Exchange, at market prices, in block transactions, or as otherwise agreed to between the Partnership and the sales agents. Proceeds are expected to be used for general partnership purposes, which may include repayment of indebtedness and funding working capital or capital expenditures. The Partnership is under no obligation to offer and sell common units under the Distribution Agreement. The Partnership did not issue or sell any common units under the Distribution Agreement during the three and nine months ended September 30, 2018. As of September 30, 2018, additional common units under the Distribution Agreement up to an aggregate sales price of $157.3 million were available for issuance.

Fair Value Measurement

9 Months Ended

Sep. 30, 2018

Fair Value Measurement

Fair Value Measurement

(12) Fair Value Measurement

In connection with the Water Acquisition, the Partnership agreed to pay Antero Resources (a) $125 million in cash if the Partnership delivers 176,295,000 barrels or more of fresh water during the period between January 1, 2017 and December 31, 2019 and (b) an additional $125 million in cash if the Partnership delivers 219,200,000 barrels or more of fresh water during the period between January 1, 2018 and December 31, 2020. This contingent consideration liability is valued based on Level 3 inputs related to expected average volumes and weighted average cost of capital.

The following table provides a reconciliation of changes in Level 3 financial liabilities measured at fair value on a recurring basis for the period shown below (in thousands):


Contingent acquisition consideration—December 31, 2017	$	208,014
Accretion and change in fair value		11,841
Contingent acquisition consideration—September 30, 2018	$	219,855

The Partnership accounts for contingent consideration in accordance with applicable accounting guidance pertaining to business combinations. The Partnership is contractually obligated to pay Antero Resources contingent consideration in connection with the Water Acquisition, and therefore recorded this contingent consideration liability at the time of the Water Acquisition. The Partnership updates its assumptions each reporting period based on new developments and adjusts such amounts to fair value based on revised assumptions, if applicable, until such consideration is satisfied through payment upon achievement of the specified objectives or it is eliminated upon failure to achieve the specified objectives.

As of September 30, 2018, the Partnership expects to pay the entire amount of the contingent consideration. 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. The fair value of the contingent consideration liability associated with future milestone payments was based on the risk adjusted present value of the contingent consideration payout.

The carrying values of accounts receivable and accounts payable at December 31, 2017 and September 30, 2018 approximated fair value because of their short-term nature. The carrying value of the amounts under the revolving credit facility at December 31, 2017 and September 30, 2018 approximated fair value because the variable interest rates are reflective of current market conditions.

Based on Level 2 market data inputs, the fair value of the Partnership’s 2024 Notes was approximately $652.4 million at September 30, 2018.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Equity Method Investments

9 Months Ended

Sep. 30, 2018

Equity Method Investments

Equity Method Investments

(13) Equity Method Investments

In the second quarter of 2016, the Partnership purchased a 15% equity interest in Stonewall, which operates the 67-mile Stonewall pipeline on which Antero Resources is an anchor shipper.

On February 6, 2017, we formed the Joint Venture to develop processing and fractionation assets in Appalachia with MarkWest, a wholly owned subsidiary of MPLX, LP. The Partnership and MarkWest each own a 50% equity interest in the Joint Venture and MarkWest operates the Joint Venture assets, which consist of processing plants in West Virginia, and a one-third interest in a MarkWest fractionator in Ohio.

The Partnership’s net income includes its proportionate share of the net income of the Joint Venture and Stonewall. When the Partnership records its proportionate share of net income, it increases equity income in the unaudited condensed consolidated statements of operations and comprehensive income and the carrying value of that investment on its balance sheet. When distributions on the Partnership’s proportionate share of net income are received, they are recorded as reductions to the carrying value of the investment on the balance sheet and are classified as cash inflows from operating activities in accordance with the nature of the distribution approach under ASU No. 2016-15. The Partnership uses the equity method of accounting to account for its investments in Stonewall and the Joint Venture because it exercises significant influence, but not control, over the entities. The Partnership’s judgment regarding the level of influence over its equity investments includes considering key factors such as its ownership interest, representation on the board of directors and participation in policy-making decisions of Stonewall and the Joint Venture.

The following table is a reconciliation of our investments in these unconsolidated affiliates (in thousands):


			MarkWest	Total Investment in
		Stonewall	Joint Venture	Unconsolidated Affiliates
Balance at December 31, 2017	$	67,128	236,174	303,302
Additional investments		—	91,419	91,419
Equity in net income of unconsolidated affiliates		8,346	19,486	27,832
Distributions from unconsolidated affiliates		(7,515)	(22,145)	(29,660)
Balance at September 30, 2018	$	67,959	324,934	392,893

Reporting Segments

9 Months Ended

Sep. 30, 2018

Reporting Segments

Reporting Segments

(14) Reporting Segments

The Partnership’s operations are located in the United States and are organized into two reporting segments: (1) gathering and processing and (2) water handling and treatment.

Gathering and Processing

The gathering and processing segment includes a network of gathering pipelines and compressor stations that collect and process production from Antero Resources’ wells in West Virginia and Ohio. The gathering and processing segment also includes equity in earnings from the Partnership’s investments in the Joint Venture with MarkWest and in Stonewall.

Water Handling and Treatment

The Partnership’s water handling and treatment segment includes two independent systems that deliver fresh water from sources including the Ohio River, local reservoirs as well as several regional waterways. The water handling and treatment segment also includes a wastewater treatment facility that was placed in service in May 2018, as well as other fluid handling services, which includes high rate transfer, wastewater transportation, disposal and treatment. See Note 2—Summary of Significant Accounting Polices, Property and Equipment.

These segments are monitored separately by management for performance and are consistent with internal financial reporting. These segments have been identified based on the differing products and services, regulatory environment and the expertise required for these operations. Management evaluates the performance of the Partnership’s business segments based on operating income. Interest expense is primarily managed and evaluated on a consolidated basis.

Summarized financial information concerning the Partnership’s segments for the periods indicated is shown in the following table (in thousands):


			Water
	Gathering and		Handling and		Consolidated
	Processing		Treatment		Total
Three Months Ended September 30, 2017
Revenues:
Revenue–Antero Resources	$	100,518		93,111		193,629
Total revenues		100,518		93,111		193,629

Operating expenses:
Direct operating		10,560		52,470		63,030
General and administrative (before equity-based compensation)		4,225		2,892		7,117
Equity-based compensation		5,111		2,088		7,199
Depreciation		21,803		8,753		30,556
Accretion of contingent acquisition consideration		—		2,556		2,556
Total expenses		41,699		68,759		110,458
Operating income	$	58,819		24,352		83,171

Equity in earnings of unconsolidated affiliates	$	7,033		—		7,033
Total assets	$	2,142,409		752,982		2,895,391
Additions to property and equipment	$	99,254		48,019		147,273

Three Months Ended September 30, 2018
Revenues:
Revenue–Antero Resources	$	133,202		132,898		266,100
Revenue–third-party		—		105		105
Total revenues		133,202		133,003		266,205

Operating expenses:
Direct operating		12,317		69,158		81,475
General and administrative (before equity-based compensation)		8,117		2,373		10,490
Equity-based compensation		3,666		862		4,528
Impairment of property and equipment		1,157		—		1,157
Depreciation		25,830		12,626		38,456
Accretion of contingent acquisition consideration		—		4,020		4,020
Accretion of asset retirement obligations		—		33		33
Total expenses		51,087		89,072		140,159
Operating income	$	82,115		43,931		126,046

Equity in earnings of unconsolidated affiliates	$	10,706		—		10,706
Total assets	$	2,483,494		931,334		3,414,828
Additions to property and equipment	$	130,870		19,271		150,141


			Water
	Gathering and		Handling and		Consolidated
	Processing		Treatment		Total
Nine months ended September 30, 2017
Revenues:
Revenue–Antero Resources	$	290,675		271,226		561,901
Revenue–third-party		264		—		264
Total revenues		290,939		271,226		562,165

Operating expenses:
Direct operating		28,596		134,296		162,892
General and administrative (before equity-based compensation)		15,242		7,884		23,126
Equity-based compensation		14,937		5,499		20,436
Depreciation		63,773		24,831		88,604
Accretion of contingent acquisition consideration		—		9,672		9,672
Total expenses		122,548		182,182		304,730
Operating income	$	168,391		89,044		257,435

Equity in earnings of unconsolidated affiliates	$	12,887		—		12,887
Total assets	$	2,142,409		752,982		2,895,391
Additions to property and equipment	$	254,619		143,470		398,089

Nine months ended September 30, 2018
Revenues:
Revenue–Antero Resources	$	359,515		386,018		745,533
Revenue–third-party		—		655		655
Gain on sale of assets–third-party		583		—		583
Total revenues		360,098		386,673		746,771

Operating expenses:
Direct operating		36,103		188,251		224,354
General and administrative (before equity-based compensation)		21,062		7,299		28,361
Equity-based compensation		13,078		3,528		16,606
Impairment of property and equipment		5,771		—		5,771
Depreciation		73,502		33,819		107,321
Accretion of contingent acquisition consideration		—		11,841		11,841
Accretion of asset retirement obligations		—		101		101
Total expenses		149,516		244,839		394,355
Operating income	$	210,582		141,834		352,416

Equity in earnings of unconsolidated affiliates	$	27,832		—		27,832
Total assets	$	2,483,494		931,334		3,414,828
Additions to property and equipment	$	337,623		68,325		405,948

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2018
Subsequent Events
Subsequent Events	(15) Subsequent Events On October 9, 2018, Antero Midstream, AMGP 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 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.

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 U.S. Securities and Exchange Commission (the “SEC”) applicable to interim financial information and should be read in the context of the December 31, 2017 consolidated financial statements and notes thereto for a more complete understanding of the Partnership’s operations, financial position, and accounting policies. The December 31, 2017 consolidated financial statements have been filed with the SEC in the Partnership’s 2017 Form 10-K.

These unaudited condensed consolidated financial statements of the Partnership 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, these unaudited condensed consolidated financial statements include all adjustments (consisting of normal and recurring accruals) considered necessary for a fair presentation of the Partnership’s financial position as of December 31, 2017 and September 30, 2018, and the results of our operations for three and nine months ended September 30, 2017 and 2018, and its cash flows for the nine months ended September 30, 2017 and 2018. The Partnership has no items of other comprehensive income; therefore, its net income is equal to its comprehensive income.

Certain costs of doing business incurred by Antero Resources on the Partnership’s behalf have been reflected in the accompanying unaudited condensed consolidated financial statements. These costs include general and administrative expenses attributed to the Partnership by Antero Resources in exchange for:

·

business services, such as payroll, accounts payable and facilities management;

·

corporate services, such as finance and accounting, legal, human resources, investor relations and public and regulatory policy; and

·

employee compensation, including equity‑based compensation.

Transactions between the Partnership and Antero Resources have been identified in the unaudited condensed consolidated financial statements (see Note 3—Transactions with Affiliates).

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 15 – Subsequent Events.

Revenue Recognition

(b) Revenue Recognition

The Partnership provides gathering and compression and water handling and treatment services under fee-based contracts primarily based on throughput or at cost plus a margin. Under these arrangements, the Partnership receives fees for gathering oil and gas products, compression services, and water handling and treatment services. The revenue the Partnership earns from these arrangements is directly related to (1) in the case of natural gas gathering and compression, the volumes of metered natural gas that it gathers, compresses, and delivers to natural gas compression sites or other transmission delivery points, (2) in the case of oil gathering, the volumes of metered oil that it gathers and delivers to other transmission delivery points, (3) in the case of fresh water services, the quantities of fresh water delivered to its customers for use in their well completion operations, (4) in the case of wastewater treatment services performed by the Partnership, the quantities of wastewater treated for our customers, or (5) in the case of flowback and produced water services provided by third parties, the third party costs the Partnership incurs plus 3%. The Partnership recognizes revenue when it satisfies a performance obligation by delivering a service to a customer.

Use of Estimates

(c)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 revenues, expenses, assets, liabilities, and the disclosure of contingent assets and liabilities. Items subject to estimates and assumptions include the useful lives of property and equipment, as well as the valuation of accrued liabilities, among others. Although management believes these estimates are reasonable, actual results could differ from these estimates.

Cash and Cash Equivalents

(d)Cash and Cash Equivalents

The Partnership considers all liquid investments purchased with an initial maturity of three months or less to be cash equivalents. The carrying value of cash and cash equivalents approximates fair value due to the short-term nature of these instruments. From time to time, the Partnership may be in the position of a “book overdraft” in which outstanding checks exceed cash and cash equivalents. The Partnership classifies book overdrafts within accounts payable within its unaudited condensed consolidated balance sheets, and classifies the change in accounts payable associated with book overdrafts as an operating activity within its unaudited condensed consolidated statements of cash flows. The Partnership classified $2.8 million of book overdrafts within accounts payable as of September 30, 2018.

Property and Equipment

(e)Property and Equipment

Property and equipment primarily consists of gathering pipelines, compressor stations, fresh water delivery pipelines and facilities, and the wastewater treatment facility and related landfill used for the disposal of waste therefrom, stated at historical cost less accumulated depreciation and amortization. The Partnership capitalizes construction-related direct labor and material costs. The Partnership also capitalized interest on capital costs during the construction phase of the wastewater treatment facility, which was placed in service in May 2018. The Partnership capitalized interest of $3 million for the three months ended September 30, 2017 and no interest for the three months ended September 30, 2018. For the nine months ended September 30, 2017 and 2018, the Partnership capitalized interest of $9 million and $4 million, respectively. Net operating expenses incurred during wastewater treatment facility commissioning were capitalized. Due to delays in reaching contractual treatment capacity of the wastewater treatment facility, the Partnership has and continues to accrue for liquidated damages from the vendor. At September 30, 2018, the Partnership had accrued $16 million for liquidated damages as a receivable and reduction in cost of the facility. Maintenance and repair costs are expensed as incurred.

Depreciation of property and equipment is computed using the straight-line method over the estimated useful lives and salvage values of assets. The depreciation of fixed assets recorded under capital lease agreements is included in depreciation expense. Uncertainties that may impact these estimates of useful lives include, among others, changes in laws and regulations relating to environmental matters, including air and water quality, restoration and abandonment requirements, economic conditions, and supply and demand for our services in the areas in which we operate. When assets are placed into service, management makes estimates with respect to useful lives and salvage values that management believes are reasonable. However, subsequent events could cause a change in estimates, thereby impacting future depreciation amounts.

Amortization of landfill airspace consists of the amortization of landfill capital costs, including those that have been incurred and capitalized and estimated future costs for landfill development and construction, as well as the amortization of asset retirement costs arising from landfill final capping, closure, and post-closure obligations. Amortization expense is recorded on a units-of-consumption basis, applying cost as a rate per-cubic yard. The rate per-cubic yard is calculated by dividing each component of the amortizable basis of the landfill by the number of cubic yards needed to fill the corresponding asset’s airspace. Landfill capital costs and closure and post-closure asset retirement costs are generally incurred to support the operation of the landfill over its entire operating life and are, therefore, amortized on a per-cubic yard basis using a landfill’s total airspace capacity. Estimates of disposal capacity and future development costs are created using input from independent engineers and internal technical teams and are reviewed at least annually. However, future events could cause a change in estimates, thereby impacting future amortization amounts.

Our investment in property and equipment as of the dates presented was as follows (in thousands):


	Estimated	December 31,		September 30,
	useful lives	2017		2018
Land	n/a	$	15,382		18,649
Gathering systems and facilities	20 years		1,781,386		2,075,542
Fresh water permanent buried pipelines and equipment	20 years		472,810		510,374
Wastewater treatment facility	30 years		—		299,567
Fresh water surface pipelines and equipment	5 years		46,139		61,865
Landfill	n/a(1)		—		58,318
Heavy trucks and equipment	5 years		—		4,831
Above ground storage tanks	10 years		4,301		4,824
Construction-in-progress(2)	n/a		654,904		316,545
Total property and equipment			2,974,922		3,350,515
Less accumulated depreciation			(369,320)		(476,641)
Property and equipment, net		$	2,605,602		2,873,874

(1) Amortization of landfill costs is recorded over the life of the landfill on a units-of-consumption basis.

(2) As of December 31, 2017, construction-in-progress included $355 million for the construction of the wastewater treatment facility and landfill, which was placed in service in May 2018.

Asset Retirement Obligations

(f)Asset Retirement Obligations

In December 2017, the Partnership completed the construction of a landfill site to be used for the disposal of waste from its wastewater treatment facility. The landfill began accepting waste in January 2018. The Partnership’s asset retirement obligations relate to its obligation to close, maintain, and monitor landfill cells and support facilities. After the entire landfill has reached capacity and is certified closed, the Partnership must continue to maintain and monitor the landfill for a post-closure period, which generally extends for 30 years. The Partnership records the fair value of its landfill retirement obligations as a liability in the period in which the regulatory obligation to retire a specific asset is triggered. For the Partnership’s individual landfill cells, the required closure and post-closure obligations under the terms of its permits and its intended operation of the landfill cell are triggered and recorded when the cell is placed into service and waste is initially disposed in the landfill cell. The fair value is based on the total estimated costs to close the landfill cell and perform post-closure activities once the landfill cell has reached capacity and is no longer accepting waste. Retirement obligations are increased each year to reflect the passage of time by accreting the balance at the weighted average credit-adjusted risk-free rate that is used to calculate the recorded liability, with accretion charged to direct costs. Actual cash expenditures to perform closure and post-closure activities reduce the retirement obligation liabilities as incurred. After initial measurement, asset retirement obligations are adjusted at the end of each period to reflect changes, if any, in the estimated future cash flows underlying the obligation. Landfill retirement assets are capitalized as the related retirement obligations are incurred, and are amortized on a units-of-consumption basis as the disposal capacity is consumed.

The Partnership is under no legal obligations, neither contractually nor under the doctrine of promissory estoppel, to restore or dismantle its gathering pipelines, compressor stations, water delivery pipelines and facilities and wastewater treatment facility upon abandonment. The Partnership’s gathering pipelines, compressor stations, fresh water delivery pipelines and facilities and wastewater treatment facility have an indeterminate life, if properly maintained. Accordingly, the Partnership is not able to make a reasonable estimate of when future dismantlement and removal dates of its pipelines, compressor stations and facilities will occur. It has been determined by the Partnership’s operational management team that abandoning all other ancillary equipment, outside of the assets stated above, would require minimal costs.

Equity-Based Compensation

(g)Equity‑Based Compensation

The Partnership’s unaudited condensed consolidated financial statements reflect various equity-based compensation awards granted by Antero Resources, as well as compensation expense associated with the Partnership’s plan. These awards include profits interests awards, restricted stock, stock options, restricted units, and phantom units. In each period, the Partnership recognizes expense in an amount allocated from Antero Resources, with the offset included in partners’ capital. See Note 3—Transactions with Affiliates for additional information regarding Antero Resources’ allocation of expenses to the Partnership.

Under the Antero Midstream Partners LP Long-Term Incentive Plan (“Midstream LTIP”), certain non-employee directors of the general partner and certain officers, employees and consultants the general partner and its affiliates are eligible to receive awards representing equity interests in the Partnership. An aggregate of 10,000,000 common units may be delivered pursuant to awards under the Midstream LTIP, subject to customary adjustments. For accounting purposes, these units are treated as if they are distributed from the Partnership to Antero Resources. Antero Resources recognizes compensation expense for the units awarded to its employees and a portion of that expense is allocated to the Partnership. See Note 8—Equity-Based Compensation.

Income Taxes

(h)Income Taxes

Our unaudited condensed consolidated financial statements do not include a provision for income taxes as we are treated as a partnership for federal and state income tax purposes, with each partner being separately taxed on its distributive share of our items of income, gain, loss, or deduction.

Fair Value Measures

(i)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 the Partnership estimates 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. The Partnership’s 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, that are observable for the asset or liability, either directly or indirectly.

The carrying values on the balance sheet of the Partnership’s cash and cash equivalents, accounts receivable—Antero Resources, accounts receivable—third party, prepaid expenses, other assets, accounts payable—Antero Resources, accounts payable, accrued liabilities, other current liabilities, other liabilities and the revolving credit facility approximate fair values due to their short-term maturities.

Investment in Unconsolidated Entities

(j)Investments in Unconsolidated Affiliates

The Partnership uses the equity method to account for its investments in companies if the investment provides the Partnership with the ability to exercise significant influence over, but not control, the operating and financial policies of the investee. The Partnership’s consolidated net income includes the Partnership’s proportionate share of the net income or loss of such companies. The Partnership’s judgment regarding the level of influence over each equity method investee includes considering key factors such as the Partnership’s ownership interest, representation on the board of directors and participation in policy-making decisions of the investee and material intercompany transactions. See Note 13–Equity Method Investments.

Adoption of New Accounting Principle

(k)Adoption of New Accounting Principle

On May 28, 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU replaces most existing revenue recognition guidance in GAAP when it became effective and was incorporated into GAAP as Accounting Standards Codification (“ASC”) Topic 606. The new standard became effective for us on January 1, 2018. The standard permits the use of either the full retrospective or modified restrospective transition method. The Partnership elected the modified retrospective transition method. The adoption of ASU 2014-09 did not have a material impact on our financial results. See Note 4—Revenue for the Partnership’s required disclosures under ASC 606.

Recently Issued Accounting Standard

(l)Recently Issued Accounting Standard

On February 25, 2016, the FASB issued ASU No. 2016-02, Leases, which requires all leasing arrangements to be presented in the balance sheet as liabilities along with a corresponding asset. The ASU will replace most existing leases guidance in GAAP when it becomes effective. The new standard becomes effective for the Partnership on January 1, 2019. Although early application is permitted, the Partnership does not plan to early adopt the ASU. The standard requires the use of the modified retrospective transition method. The Partnership is evaluating the effect that ASU 2016-02 will have on its consolidated financial statements and related disclosures. The Partnership is evaluating the standard’s applicability to its various contractual arrangements with Antero Resources, and the Partnership believes that the application of the ASU to its contractual arrangements with Antero Resources could be subject to differing interpretations. The accounting treatment for these arrangements under the ASU could include (i) the recognition of our Antero contracts as leases under the ASU, (ii) characterization of our servicing revenues from gathering, compression, and water handling and treatment as revenues from leasing or financing, and (iii) derecognition of assets on our balance sheet that are used to provide services under contracts containing variable payment terms. Other interpretations and applications of the standard may be possible, including no material changes to the accounting for these contractual arrangements. The Partnership is updating its accounting policies and internal controls that would be impacted by the new guidance and implementing information technology tools to assist with its ongoing lease data collection and analysis to ensure readiness for adoption in the first quarter of 2019. The Partnership continues to monitor relevant industry guidance regarding implementation of ASU 2016-02 and will adjust its implementation of the standard as necessary. The Partnership believes that adoption of the standard will not impact its operational strategies, growth prospects, or cash flow.

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2018

Summary of Significant Accounting Policies

Schedule of investment in property and equipment

Our investment in property and equipment as of the dates presented was as follows (in thousands):


	Estimated	December 31,		September 30,
	useful lives	2017		2018
Land	n/a	$	15,382		18,649
Gathering systems and facilities	20 years		1,781,386		2,075,542
Fresh water permanent buried pipelines and equipment	20 years		472,810		510,374
Wastewater treatment facility	30 years		—		299,567
Fresh water surface pipelines and equipment	5 years		46,139		61,865
Landfill	n/a(1)		—		58,318
Heavy trucks and equipment	5 years		—		4,831
Above ground storage tanks	10 years		4,301		4,824
Construction-in-progress(2)	n/a		654,904		316,545
Total property and equipment			2,974,922		3,350,515
Less accumulated depreciation			(369,320)		(476,641)
Property and equipment, net		$	2,605,602		2,873,874

(1) Amortization of landfill costs is recorded over the life of the landfill on a units-of-consumption basis.

(2) As of December 31, 2017, construction-in-progress included $355 million for the construction of the wastewater treatment facility and landfill, which was placed in service in May 2018.

Revenue (Tables)

9 Months Ended

Sep. 30, 2018

Revenue

Schedule of minimum revenue amounts under the minimum volume commitments

Minimum revenue amounts under the minimum volume commitments are as follows (in thousands):


	Remainder		Year Ended December 31,
	of 2018		2019	2020	2021	2022	2023	Thereafter	Total
Minimum revenue under the Gathering and Compression Agreement	$	24,351	158,725	159,160	158,725	158,725	158,725	498,917	1,317,328
Minimum revenue under the Water Handling and Treatment Agreement		—	165,564	—	—	—	—	—	165,564
Total	$	24,351	324,289	159,160	158,725	158,725	158,725	498,917	1,482,892

Schedule of disaggregation of revenue

In the following table, revenue is disaggregated by type of service and type of fee (in thousands). The table also identifies the reportable segment to which the disaggregated revenues relate. For more information on reportable segments, see Note 14—Reportable Segments.


	Three Months Ended September 30,				Nine Months Ended September 30,				Segment to which
	2017		2018		2017		2018		revenues relate
Revenue from contracts with customers
Type of service
Gathering—low pressure	$	46,153		63,884	$	141,783		174,539	Gathering and Processing
Gathering—high pressure		33,365		38,409		90,095		102,714	Gathering and Processing
Compression		21,000		30,909		58,997		82,262	Gathering and Processing
Condensate gathering		—		—		64		—	Gathering and Processing
Fresh water delivery		48,352		68,144		156,635		222,367	Water Handling and Treatment
Wastewater treatment		—		5,260		—		8,431	Water Handling and Treatment
Other fluid handling		44,759		59,599		114,591		155,875	Water Handling and Treatment
Total	$	193,629		266,205	$	562,165		746,188
Type of contract
Fixed Fee	$	100,518		133,202	$	290,939		359,515	Gathering and Processing
Fixed Fee		48,352		73,404		156,635		230,798	Water Handling and Treatment
Cost plus 3%		44,759		59,599		114,591		155,875	Water Handling and Treatment
Total	$	193,629		266,205	$	562,165		746,188

Gain on sale of assets		—		—		—		583	Gathering and Processing
Total revenue	$	193,629		266,205		562,165		746,771

Long-term Debt (Tables)

9 Months Ended

Sep. 30, 2018

Long-term Debt.

Schedule of long-term debt

Long-term debt was as follows at December 31, 2017 and September 30, 2018 (in thousands):


	December 31, 2017		September 30, 2018
Credit Facility (a)	$	555,000		875,000
5.375% senior notes due 2024 (b)		650,000		650,000
Net unamortized debt issuance costs		(9,000)		(8,146)
Total long-term debt	$	1,196,000		1,516,854

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Accrued Liabilities (Tables)

9 Months Ended

Sep. 30, 2018

Accrued Liabilities

Schedule of accrued liabilities

Accrued liabilities as of December 31, 2017 and September 30, 2018 consisted of the following items (in thousands):


	December 31,		September 30,
	2017		2018
Capital expenditures	$	63,286		48,067
Operating expenses		29,905		35,607
Interest expense		10,508		1,988
Other		2,307		2,596
Total accrued liabilities	$	106,006		88,258

Asset Retirement Obligations (Tables)

9 Months Ended

Sep. 30, 2018

Asset Retirement Obligations

Schedule of reconciliation of our asset retirement obligations

The following is a reconciliation of our asset retirement obligations for the period shown below (in thousands):


Asset retirement obligations—December 31, 2017	$	—
Obligations incurred		3,047
Accretion expense		101
Asset retirement obligations—September 30, 2018	$	3,148

Equity-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2018

Equity-Based Compensation

Summary of restricted unit and phantom unit awards activity


		Weighted average		Aggregate
	Number of	grant date		intrinsic value
	units	fair value		(in thousands)
Total awarded and unvested—December 31, 2017	1,042,963	$	28.69	$	30,288
Granted	247,692	$	25.84
Vested	(144,620)	$	30.17
Forfeited	(93,419)	$	28.64
Total awarded and unvested—September 30, 2018	1,052,616	$	28.15	$	30,168

Partnership Equity and Distributions (Tables)

9 Months Ended

Sep. 30, 2018

Partnership Equity and Distributions

Summary of percentage allocations for distributions

If cash distributions to the Partnership’s unitholders exceed $0.1955 per common unit in any quarter, the Partnership’s unitholders and the holder of the Partnership’s incentive distribution rights (“IDRs”), will receive distributions according to the following percentage allocations:



	Marginal Percentage
Total Quarterly Distribution	Interest in Distributions
Target Amount	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

			Distributions
Quarter and Year	Record Date	Distribution Date	Common unitholders		Holder of IDRs		Total		Distributions per unit
Q4 2016	February 1, 2017	February 8, 2017	$	50,090		7,543		57,633	$	0.280
*	April 21, 2017	April 30, 2017		75		—		75		*
Q1 2017	May 3, 2017	May 10, 2017		55,753		11,553		67,306		0.300
Q2 2017	August 3, 2017	August 16, 2017		59,695		15,328		75,023		0.320
Q3 2017	November 1, 2017	November 16, 2017		63,454		19,067		82,521		0.340
*	November 12, 2017	November 17, 2017		1,392		—		1,392		*
	Total 2017		$	230,459		53,491		283,950

Q4 2017	February 1, 2018	February 13, 2018	$	68,231		23,772		92,003	$	0.365
*	April 15, 2018	April 20, 2018		263		—		263		*
Q1 2018	May 3, 2018	May 18, 2018		72,943		28,461		101,404		0.390
*	July 15, 2018	July 31, 2018		21		—		21		*
Q2 2018	August 2, 2018	August 17, 2018		77,624		33,138		110,762		0.415
	Total 2018		$	219,082		85,371		304,453

* Distribution equivalent rights on limited partner interests that vested under the Midstream LTIP.

Net Income Per Limited Partner Unit (Tables)

9 Months Ended

Sep. 30, 2018

Net Income Per Limited Partner Unit

Schedule of net income per common and subordinated unit

The Partnership’s calculation of net income per limited partner unit for the periods indicated is as follows (in thousands, except per unit data):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2018		2017		2018
Net income	$	80,893		119,764	$	243,160		337,335
Less:
Net income attributable to incentive distribution rights		(19,067)		(37,816)		(45,948)		(99,414)
Limited partner interest in net income	$	61,826		81,948	$	197,212		237,921

Net income per limited partner unit–basic and diluted	$	0.33		0.44	$	1.06		1.27

Weighted average limited partner units outstanding–basic		186,581		187,044		185,240		186,999

Weighted average limited partner units outstanding–diluted		187,145		187,502		185,728		187,342

Fair Value Measurement (Tables)

9 Months Ended

Sep. 30, 2018

Fair Value Measurement

Schedule of reconciliation of changes in Level 3 financial liabilities measured at fair value on a recurring basis

The following table provides a reconciliation of changes in Level 3 financial liabilities measured at fair value on a recurring basis for the period shown below (in thousands):


Contingent acquisition consideration—December 31, 2017	$	208,014
Accretion and change in fair value		11,841
Contingent acquisition consideration—September 30, 2018	$	219,855

Equity Method Investments (Tables)

9 Months Ended

Sep. 30, 2018

Equity Method Investments

Schedule of reconciliation of investments in unconsolidated affiliates

The following table is a reconciliation of our investments in these unconsolidated affiliates (in thousands):


			MarkWest	Total Investment in
		Stonewall	Joint Venture	Unconsolidated Affiliates
Balance at December 31, 2017	$	67,128	236,174	303,302
Additional investments		—	91,419	91,419
Equity in net income of unconsolidated affiliates		8,346	19,486	27,832
Distributions from unconsolidated affiliates		(7,515)	(22,145)	(29,660)
Balance at September 30, 2018	$	67,959	324,934	392,893

Reporting Segments (Tables)

9 Months Ended

Sep. 30, 2018

Reporting Segments

Schedule of financial information concerning the Partnership's segments

Summarized financial information concerning the Partnership’s segments for the periods indicated is shown in the following table (in thousands):


			Water
	Gathering and		Handling and		Consolidated
	Processing		Treatment		Total
Three Months Ended September 30, 2017
Revenues:
Revenue–Antero Resources	$	100,518		93,111		193,629
Total revenues		100,518		93,111		193,629

Operating expenses:
Direct operating		10,560		52,470		63,030
General and administrative (before equity-based compensation)		4,225		2,892		7,117
Equity-based compensation		5,111		2,088		7,199
Depreciation		21,803		8,753		30,556
Accretion of contingent acquisition consideration		—		2,556		2,556
Total expenses		41,699		68,759		110,458
Operating income	$	58,819		24,352		83,171

Equity in earnings of unconsolidated affiliates	$	7,033		—		7,033
Total assets	$	2,142,409		752,982		2,895,391
Additions to property and equipment	$	99,254		48,019		147,273

Three Months Ended September 30, 2018
Revenues:
Revenue–Antero Resources	$	133,202		132,898		266,100
Revenue–third-party		—		105		105
Total revenues		133,202		133,003		266,205

Operating expenses:
Direct operating		12,317		69,158		81,475
General and administrative (before equity-based compensation)		8,117		2,373		10,490
Equity-based compensation		3,666		862		4,528
Impairment of property and equipment		1,157		—		1,157
Depreciation		25,830		12,626		38,456
Accretion of contingent acquisition consideration		—		4,020		4,020
Accretion of asset retirement obligations		—		33		33
Total expenses		51,087		89,072		140,159
Operating income	$	82,115		43,931		126,046

Equity in earnings of unconsolidated affiliates	$	10,706		—		10,706
Total assets	$	2,483,494		931,334		3,414,828
Additions to property and equipment	$	130,870		19,271		150,141


			Water
	Gathering and		Handling and		Consolidated
	Processing		Treatment		Total
Nine months ended September 30, 2017
Revenues:
Revenue–Antero Resources	$	290,675		271,226		561,901
Revenue–third-party		264		—		264
Total revenues		290,939		271,226		562,165

Operating expenses:
Direct operating		28,596		134,296		162,892
General and administrative (before equity-based compensation)		15,242		7,884		23,126
Equity-based compensation		14,937		5,499		20,436
Depreciation		63,773		24,831		88,604
Accretion of contingent acquisition consideration		—		9,672		9,672
Total expenses		122,548		182,182		304,730
Operating income	$	168,391		89,044		257,435

Equity in earnings of unconsolidated affiliates	$	12,887		—		12,887
Total assets	$	2,142,409		752,982		2,895,391
Additions to property and equipment	$	254,619		143,470		398,089

Nine months ended September 30, 2018
Revenues:
Revenue–Antero Resources	$	359,515		386,018		745,533
Revenue–third-party		—		655		655
Gain on sale of assets–third-party		583		—		583
Total revenues		360,098		386,673		746,771

Operating expenses:
Direct operating		36,103		188,251		224,354
General and administrative (before equity-based compensation)		21,062		7,299		28,361
Equity-based compensation		13,078		3,528		16,606
Impairment of property and equipment		5,771		—		5,771
Depreciation		73,502		33,819		107,321
Accretion of contingent acquisition consideration		—		11,841		11,841
Accretion of asset retirement obligations		—		101		101
Total expenses		149,516		244,839		394,355
Operating income	$	210,582		141,834		352,416

Equity in earnings of unconsolidated affiliates	$	27,832		—		27,832
Total assets	$	2,483,494		931,334		3,414,828
Additions to property and equipment	$	337,623		68,325		405,948

Business and Organization (Details)	9 Months Ended
Business and Organization (Details)	Sep. 30, 2018	Feb. 06, 2017	Jun. 30, 2016
Antero Midstream LLC
Business and Organization
Ownership interest in subsidiaries (as a percent)	100.00%
Antero Water
Business and Organization
Ownership interest in subsidiaries (as a percent)	100.00%
Antero Treatment
Business and Organization
Ownership interest in subsidiaries (as a percent)	100.00%
Stonewall Gas Gathering LLC
Business and Organization
Ownership percentage	15.00%		15.00%
Appalachia Joint venture
Business and Organization
Ownership percentage		50.00%
MarkWest \| Appalachia Joint venture
Business and Organization
Ownership percentage	50.00%	50.00%

Business and Organization - Simplification (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 09, 2018	Oct. 31, 2018	Oct. 30, 2018	Oct. 26, 2017
Revolving credit facility
Business and Organization
Maximum borrowing capacity				$ 1,500
Simplification Agreement \| Revolving credit facility \| Subsequent event
Business and Organization
Maximum borrowing capacity		$ 2,000	$ 1,500
Simplification Agreement \| Antero Resources \| Subsequent event \| Forecast
Business and Organization
Cash without interest	$ 3.00
Number of new shares issued	1.6023
Simplification Agreement \| AM Public Unitholders \| Subsequent event \| Forecast
Business and Organization
Cash without interest	$ 3.415
Number of new shares issued	1.6350
Threshold days	20 days
Simplification Agreement \| New AM \| Subsequent event \| Forecast
Business and Organization
New AM's Common stock in exchange of Series B units	17,350,000
Aggregate cash consideration to be paid	$ 598

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	Dec. 31, 2017
Cash and Cash Equivalents
Book overdrafts	$ 2,800		$ 2,800
Property and equipment:
Total property and equipment	3,350,515		3,350,515		$ 2,974,922
Less accumulated depreciation	(476,641)		(476,641)		(369,320)
Property and equipment, net	2,873,874		2,873,874		2,605,602
Interest cost capitalized	0	$ 3,000	$ 4,000	$ 9,000
Asset Retirement Obligations
Post-closure period for landfill to maintain and monitor			30 years
Impairment of Long-Lived Assets
Impairment of property and equipment	$ 1,157		$ 5,771
Stock-Based Compensation
Margin over out-of-pocket costs related to water handling and treatment for revenue recognition (as a percent)			3.00%
Midstream LTIP
Stock-Based Compensation
Number of stock-based compensation awards authorized	10,000,000		10,000,000
Land
Property and equipment:
Total property and equipment	$ 18,649		$ 18,649		15,382
Gathering systems and facilities
Property and equipment:
Estimated useful lives			20 years
Total property and equipment	2,075,542		$ 2,075,542		1,781,386
Fresh water permanent buried pipelines and equipment
Property and equipment:
Estimated useful lives			20 years
Total property and equipment	510,374		$ 510,374		472,810
Wastewater treatment facility
Property and equipment:
Estimated useful lives			30 years
Total property and equipment	299,567		$ 299,567
Impairment of Long-Lived Assets
Impairment of assets	16,000
Fresh water surface pipelines and equipment
Property and equipment:
Estimated useful lives			5 years
Total property and equipment	61,865		$ 61,865		46,139
Landfill
Property and equipment:
Total property and equipment	58,318		$ 58,318
Heavy trucks and equipment
Property and equipment:
Estimated useful lives			5 years
Total property and equipment	4,831		$ 4,831
Above ground storage tanks
Property and equipment:
Estimated useful lives			10 years
Total property and equipment	4,824		$ 4,824		4,301
Construction-in-progress
Property and equipment:
Total property and equipment	$ 316,545		$ 316,545		654,904
Construction-in-progress - wastewater treatment facility
Property and equipment:
Total property and equipment					$ 355,000

Transactions with Affiliates (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Allocation of costs
General and administrative expense	$ 12.8	$ 13.0	$ 39.9	$ 39.8
Service
Allocation of costs
Direct labor expenses	$ 1.8	$ 2.6	$ 5.3	$ 5.0

Revenue (Details)	9 Months Ended
Revenue (Details)	Sep. 30, 2018 USD ($) item $ / bbl $ / Mcf
Gathering And Compression Agreement
Agreements
Low pressure gathering fee \| $ / Mcf	0.30
High pressure gathering fee \| $ / Mcf	0.18
Compression fee \| $ / Mcf	0.18
Term of new construction	10 years
Gathering And Compression Agreement \| Minimum
Agreements
Minimum volume commitment that require Antero to pay	70.00%
Gathering And Compression Agreement \| Maximum
Agreements
Minimum volume commitment that require Antero to pay	75.00%
Water Services Agreement
Agreements
Term of agreement with Antero	20 years
Water Service Agreement fee \| $ / bbl	3.116
Waste water treatment and high rate transfer operating expenses \| $	$ 4.00
Third party out of pocket costs reimbursement (as a percent)	3.00%
Minimum Obligation
2018 \| item	120,000
2019 \| item	120,000
Water Services Agreement \| West Virginia
Agreements
Water Service Agreement fee \| $ / bbl	3.685
Water Services Agreement \| Ohio
Agreements
Water Service Agreement fee \| $ / bbl	3.635

Revenue - Minimum Volume Commitments (Details) $ in Thousands	Sep. 30, 2018 USD ($)
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 1,482,892
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 24,351
Expected timing of satisfaction period	3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 324,289
Expected timing of satisfaction period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 159,160
Expected timing of satisfaction period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 158,725
Expected timing of satisfaction period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 158,725
Expected timing of satisfaction period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 158,725
Expected timing of satisfaction period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 498,917
Expected timing of satisfaction period
Gathering And Compression Agreement
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 1,317,328
Gathering And Compression Agreement \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 24,351
Expected timing of satisfaction period	3 months
Gathering And Compression Agreement \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 158,725
Expected timing of satisfaction period	12 months
Gathering And Compression Agreement \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 159,160
Expected timing of satisfaction period	12 months
Gathering And Compression Agreement \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 158,725
Expected timing of satisfaction period	12 months
Gathering And Compression Agreement \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 158,725
Expected timing of satisfaction period	12 months
Gathering And Compression Agreement \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 158,725
Expected timing of satisfaction period	12 months
Gathering And Compression Agreement \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 498,917
Expected timing of satisfaction period
Water Services Agreement
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 165,564
Water Services Agreement \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Minimum revenue amounts under the minimum volume commitments
Minimum revenue amounts	$ 165,564
Expected timing of satisfaction period	12 months

Revenue - Disaggregation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Revenue - Disaggregation (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue
Revenue from contracts with customers	$ 266,205	$ 193,629	$ 746,188	$ 562,165
Gain on sale of assets - Antero Resources			583
Total revenue	266,205	193,629	746,771	562,165
Gathering—low pressure
Disaggregation of Revenue
Revenue from contracts with customers	63,884	46,153	174,539	141,783
Gathering—high pressure
Disaggregation of Revenue
Revenue from contracts with customers	38,409	33,365	102,714	90,095
Compression
Disaggregation of Revenue
Revenue from contracts with customers	30,909	21,000	82,262	58,997
Condensate gathering
Disaggregation of Revenue
Revenue from contracts with customers				64
Fresh water delivery
Disaggregation of Revenue
Revenue from contracts with customers	68,144	48,352	222,367	156,635
Wastewater treatment
Disaggregation of Revenue
Revenue from contracts with customers	5,260		8,431
Other fluid handling
Disaggregation of Revenue
Revenue from contracts with customers	59,599	44,759	155,875	114,591
Cost plus 3%
Disaggregation of Revenue
Revenue from contracts with customers	59,599	44,759	155,875	114,591
Gathering And Processing
Disaggregation of Revenue
Gain on sale of assets - Antero Resources			583
Total revenue	133,202	100,518	360,098	290,939
Gathering And Processing \| Fixed Fee
Disaggregation of Revenue
Revenue from contracts with customers	133,202	100,518	359,515	290,939
Water Handling and Treatment
Disaggregation of Revenue
Total revenue	133,003	93,111	386,673	271,226
Water Handling and Treatment \| Fixed Fee
Disaggregation of Revenue
Revenue from contracts with customers	$ 73,404	$ 48,352	$ 230,798	$ 156,635

Revenue - Transaction Price Allocation and Contract Balances (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Revenue
Original expected duration	true
Receivables from contracts with customers	$ 116	$ 110

Long-term Debt (Details)		9 Months Ended
Long-term Debt (Details)	Sep. 13, 2016 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Oct. 26, 2017 USD ($)
Long-term debt
Net unamortized debt issuance costs		$ (8,146,000)	$ (9,000,000)
Long-term debt, net		1,516,854,000	1,196,000,000
Revolving credit facility
Long-term debt
Long-term debt		$ 875,000,000	$ 555,000,000
Maximum borrowing capacity				$ 1,500,000,000
Weighted average interest rate (as a percent)		3.39%	2.81%
Revolving credit facility \| Minimum
Long-term debt
Commitment fees on the unused portion (as a percent)		0.25%
Commitment fees on the unused portion during investment grade period (as a percent)		0.175%
Revolving credit facility \| Maximum
Long-term debt
Commitment fees on the unused portion (as a percent)		0.375%
Commitment fees on the unused portion during investment grade period (as a percent)		0.375%
Revolving credit facility \| Investment Grade Period \| Minimum
Long-term debt
Margin rates		12.5
Revolving credit facility \| Investment Grade Period \| Maximum
Long-term debt
Margin rates		200
Revolving credit facility \| Not Investment Grade Period \| Minimum
Long-term debt
Margin rates		25
Revolving credit facility \| Not Investment Grade Period \| Maximum
Long-term debt
Margin rates		225
Letter of credit
Long-term debt
Outstanding letters of credit		$ 0	$ 0
5.375% Senior Notes due 2024
Long-term debt
Long-term debt		$ 650,000,000	$ 650,000,000
Face amount	$ 650,000,000
Interest rate (as a percent)	5.375%
Debt instrument redemption percentage upon change of control	101.00%
5.375% Senior Notes due 2024 \| Maximum
Long-term debt
Percent of aggregate principal amount that can be redeemed	35.00%
5.375% Senior Notes due 2024 \| Prior to September 15, 2019
Long-term debt
Debt instrument redemption percentage	105.375%
Debt instrument redemption percentage with payment of premium and interest	100.00%
5.375% Senior Notes due 2024 \| On or after September 15, 2019
Long-term debt
Debt instrument redemption percentage	104.031%
5.375% Senior Notes due 2024 \| On or after September 15, 2022
Long-term debt
Debt instrument redemption percentage	100.00%

Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accrued Liabilities
Capital expenditures	$ 48,067	$ 63,286
Operating expenses	35,607	29,905
Interest expense	1,988	10,508
Other	2,596	2,307
Accrued liabilities	$ 88,258	$ 106,006

Asset Retirement Obligations (Details) $ in Thousands	9 Months Ended
Asset Retirement Obligations (Details) $ in Thousands	Sep. 30, 2018 USD ($)
Asset Retirement Obligations
Obligations incurred	$ 3,047
Accretion expense	101
Asset Retirement Obligation, Ending Balance	$ 3,148

Equity Based Compensation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Additional disclosures
Equity-based compensation	$ 4,528	$ 7,199	$ 16,606	$ 20,436
Midstream LTIP
Additional disclosures
Number of stock-based compensation awards authorized	10,000,000		10,000,000
Unamortized expense	$ 16,300		$ 16,300
Number of shares available for future grant under the Plan	7,752,232		7,752,232
Weighted average period for recognizing unrecognized stock-based compensation expense			2 years 6 months
Restricted unit and phantom unit awards
Number of units
Total awarded and unvested at the beginning of the period (in shares)			1,042,963
Granted (in shares)			247,692
Vested (in shares)			(144,620)
Forfeited (in shares)			(93,419)
Total awarded and unvested at the end of the period (in shares)	1,052,616		1,052,616
Weighted average grant date fair value
Total awarded and unvested at the beginning of the period (in dollars per unit)			$ 28.69
Granted (in dollars per unit)			25.84
Vested (in dollars per unit)			30.17
Forfeited (in dollars per unit)			28.64
Total awarded and unvested at the end of the period (in dollars per unit)	$ 28.15		$ 28.15
Aggregate intrinsic value
Total awarded and unvested at the beginning of the period			$ 30,288
Total awarded and unvested at the end of the period	$ 30,168		30,168
Various equity based compensation plans \| Antero Resources
Additional disclosures
Unamortized expense	$ 79,000		$ 79,000

Partnership Equity and Distributions (Details) $ / shares in Units, $ in Thousands													9 Months Ended	12 Months Ended
	Oct. 17, 2018 $ / shares	Aug. 17, 2018 USD ($) $ / shares	Jul. 31, 2018 USD ($)	May 18, 2018 USD ($) $ / shares	Apr. 20, 2018 USD ($)	Feb. 13, 2018 USD ($) $ / shares	Nov. 17, 2017 USD ($)	Nov. 16, 2017 USD ($) $ / shares	Aug. 16, 2017 USD ($) $ / shares	May 10, 2017 USD ($) $ / shares	Apr. 30, 2017 USD ($)	Feb. 08, 2017 USD ($) $ / shares	Sep. 30, 2018 USD ($) $ / shares $ / item	Dec. 31, 2017 USD ($)
Partnership equity and distributions
Annual cash distribution (per unit)													0.68
Minimum cash distributions to trigger unitholder and general partner distributions \| $ / shares													$ 0.1955
Distributions \| $		$ 110,762	$ 21	$ 101,404	$ 263	$ 92,003	$ 1,392	$ 82,521	$ 75,023	$ 67,306	$ 75	$ 57,633	$ 304,453	$ 283,950
Distributions per limited partner unit (in dollars per share) \| $ / shares		$ 0.4150		$ 0.3900		$ 0.3650		$ 0.3400	$ 0.3200	$ 0.3000		$ 0.2800
General Partner
Partnership equity and distributions
Distributions \| $		$ 33,138		$ 28,461		$ 23,772		$ 19,067	$ 15,328	$ 11,553		$ 7,543	85,371	53,491
General Partner \| Subsequent event
Partnership equity and distributions
Cash distribution declared (in dollars per unit) \| $ / shares	$ 0.44
Common units
Partnership equity and distributions
Distributions \| $		$ 77,624	$ 21	$ 72,943	$ 263	$ 68,231	$ 1,392	$ 63,454	$ 59,695	$ 55,753	$ 75	$ 50,090	$ 219,082	$ 230,459
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%
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%
Above $0.2550
Partnership equity and distributions
Unitholders marginal percentage interest in distribution													50.00%
General Partners marginal percentage interest in distribution													50.00%
Minimum
Partnership equity and distributions
Minimum quarterly cash distribution (per unit)													0.17
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
Minimum \| Above $0.2550
Partnership equity and distributions
Pro rata cash distribution to the holders of common and subordinate units													0.2550
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

Net Income Per Limited Partner Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						6 Months Ended	9 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Net income per limited partner unit
Net income	$ 119,764	$ 109,466	$ 108,105	$ 80,893	$ 87,176	$ 75,091		$ 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
Net income per limited partner unit–basic	$ 0.44			$ 0.33				$ 1.27	$ 1.06
Weighted average limited partner units outstanding - basic	187,044,000			186,581,000				186,999,000	185,240,000
Weighted average limited partner units outstanding - diluted	187,502,000			187,145,000				187,342,000	185,728,000
Phantom share units
Net income per limited partner unit
Weighted average limited partner units outstanding - diluted	457,795						343,227
Restricted and phantom unit award
Net income per limited partner unit
Weighted average limited partner units outstanding - diluted							187,342,199
Weighted average units outstanding:
Antidilutive securities excluded from computation of earnings per share	0							0
Common units
Net income per limited partner unit
Weighted average limited partner units outstanding - diluted	187,501,733

Sale of Common Units Under Equity Distribution Agreement (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2016	Sep. 30, 2018
Sale of Common Units Under Equity Distribution Agreement
Maximum aggregate offering price of common limited partners units under an equity distribution agreement	$ 250.0
Remaining capacity to issue additional common units under an equity distribution agreement		$ 157.3

Fair Value Measurement (Details) $ in Thousands	1 Months Ended	9 Months Ended
Fair Value Measurement (Details) $ in Thousands	Sep. 30, 2015 USD ($) bbl	Sep. 30, 2018 USD ($)
Reconciliation of changes in Level 3 financial liabilities measured at fair value on a recurring basis
Beginning balance		$ 208,014
Accretion and change in fair value		11,841
Ending balance		219,855
Level 2 \| 5.375% Senior Notes due 2024
Fair value measurement
Debt instrument fair value		$ 652,400
Contribution Agreement \| Contingent Consideration Period One
Fair value measurement
Contingent consideration	$ 125,000
Threshold number of barrels of water to trigger contingent consideration payment \| bbl	176,295,000
Contribution Agreement \| Contingent Consideration Period Two
Fair value measurement
Contingent consideration	$ 125,000
Threshold number of barrels of water to trigger contingent consideration payment \| bbl	219,200,000

Equity Method Investments (Details) $ in Thousands		3 Months Ended		9 Months Ended
Equity Method Investments (Details) $ in Thousands	Feb. 06, 2017	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2016 mi
Investments in unconsolidated affiliates
Balance at beginning of period				$ 303,302
Additional investments				91,419
Equity in net income of unconsolidated affiliates		$ 10,706	$ 7,033	27,832	$ 12,887
Distributions from unconsolidated affiliates				(29,660)	$ (10,120)
Balance at end of period		392,893		392,893
MarkWest
Investments in unconsolidated affiliates
Balance at beginning of period				236,174
Additional investments				91,419
Equity in net income of unconsolidated affiliates				19,486
Distributions from unconsolidated affiliates				(22,145)
Balance at end of period		324,934		324,934
Stonewall
Investments in unconsolidated affiliates
Balance at beginning of period				67,128
Equity in net income of unconsolidated affiliates				8,346
Distributions from unconsolidated affiliates				(7,515)
Balance at end of period		$ 67,959		$ 67,959
Appalachia Joint venture
Equity Method Investments
Ownership percentage	50.00%
Percentage of interest held by joint venture in third party fractionator in Ohio	33.33%
Appalachia Joint venture \| MarkWest
Equity Method Investments
Ownership percentage	50.00%	50.00%		50.00%
Stonewall Gas Gathering LLC
Equity Method Investments
Ownership percentage		15.00%		15.00%		15.00%
Number of miles \| mi						67

Reporting Segments (Details) $ in Thousands	3 Months Ended		9 Months Ended
Reporting Segments (Details) $ in Thousands	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) segment item	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Reporting Segments
Number of reportable segments \| segment			2
Revenues:
Revenue	$ 266,205	$ 193,629	$ 746,188	$ 562,165
Gain on sale of assets - Antero Resources			583
Total revenue	266,205	193,629	746,771	562,165
Operating expenses:
Direct operating	81,475	63,030	224,354	162,892
General and administrative expense (before equity-based compensation)	10,490	7,117	28,361	23,126
Equity-based compensation	4,528	7,199	16,606	20,436
Impairment of property and equipment	1,157		5,771
Depreciation	38,456	30,556	107,321	88,604
Accretion of contingent acquisition consideration	4,020	2,556	11,841	9,672
Accretion of asset retirement obligations	33		101
Total operating expenses	140,159	110,458	394,355	304,730
Operating income	126,046	83,171	352,416	257,435
Equity in earnings of unconsolidated affiliates	10,706	7,033	27,832	12,887
Total assets	3,414,828	2,895,391	3,414,828	2,895,391	$ 3,042,209
Additions to property and equipment	150,141	147,273	405,948	398,089
Antero Resources
Revenues:
Revenue	266,100	193,629	745,533	561,901
Third party
Revenues:
Revenue	105		655	264
Gathering And Processing
Revenues:
Gain on sale of assets - Antero Resources			583
Total revenue	133,202	100,518	360,098	290,939
Operating expenses:
Direct operating	12,317	10,560	36,103	28,596
General and administrative expense (before equity-based compensation)	8,117	4,225	21,062	15,242
Equity-based compensation	3,666	5,111	13,078	14,937
Impairment of property and equipment	1,157		5,771
Depreciation	25,830	21,803	73,502	63,773
Total operating expenses	51,087	41,699	149,516	122,548
Operating income	82,115	58,819	210,582	168,391
Equity in earnings of unconsolidated affiliates	10,706	7,033	27,832	12,887
Total assets	2,483,494	2,142,409	2,483,494	2,142,409
Additions to property and equipment	130,870	99,254	337,623	254,619
Gathering And Processing \| Antero Resources
Revenues:
Revenue	133,202	100,518	$ 359,515	290,675
Gathering And Processing \| Third party
Revenues:
Revenue				264
Water Handling and Treatment
Reporting Segments
Number of independent fresh water systems \| item			2
Revenues:
Total revenue	133,003	93,111	$ 386,673	271,226
Operating expenses:
Direct operating	69,158	52,470	188,251	134,296
General and administrative expense (before equity-based compensation)	2,373	2,892	7,299	7,884
Equity-based compensation	862	2,088	3,528	5,499
Depreciation	12,626	8,753	33,819	24,831
Accretion of contingent acquisition consideration	4,020	2,556	11,841	9,672
Accretion of asset retirement obligations	33		101
Total operating expenses	89,072	68,759	244,839	182,182
Operating income	43,931	24,352	141,834	89,044
Total assets	931,334	752,982	931,334	752,982
Additions to property and equipment	19,271	48,019	68,325	143,470
Water Handling and Treatment \| Antero Resources
Revenues:
Revenue	132,898	$ 93,111	386,018	$ 271,226
Water Handling and Treatment \| Third party
Revenues:
Revenue	$ 105		$ 655

Subsequent Events (Details)	Oct. 17, 2018 $ / shares
Subsequent event \| General Partner
Subsequent events
Cash distribution declared (in dollars per unit)	$ 0.44