Business and Organization	12 Months Ended
Dec. 31, 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 consolidated financial statements as of December 31, 2018, include the accounts of the Partnership, Antero Midstream LLC (“Midstream Operating”), 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’s gathering and compression assets consist of high and low pressure gathering pipelines, compressor stations, and processing and fractionation plants that collect and process natural gas and NGLs from Antero Resources’ wells in West Virginia and Ohio. The Partnership’s water handling and treatment assets include two independent systems that deliver fresh water from sources including the Ohio River, local reservoirs as well as several regional waterways, an advanced wastewater treatment facility placed into service in 2018 and a related landfill used for the disposal of waste therefrom. 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 with MarkWest (the “Joint Venture”). See Note 14—Investments in Unconsolidated Affiliates. The Partnership has been determined to be a variable interest entity and its financial statements are consolidated within the financial statements of Antero Resources (NYSE: AR), its primary beneficiary for financial reporting purposes. On April 6, 2017, in connection with its initial public offering, Antero Resources Midstream Management LLC (“ARMM”) formed Antero Midstream Partners GP LLC (“AMP GP” or our “general partner”), a Delaware limited liability company, as a wholly owned subsidiary, and, on April 11, 2017, assigned to AMP GP the general partner interest in us. Concurrent with the assignment, AMP GP was admitted as the Partnership’s sole general partner and ARMM ceased to be our general partner. On May 9, 2017, ARMM closed its initial public offering. In connection with the offering, ARMM was converted into a Delaware limited partnership, and changed its name to Antero Midstream GP LP (“AMGP”). (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 partially owned 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, unitholders of the Partnership and holders of Series B Units 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 (the “Available Cash”) and Antero Resources received $3.00 in cash per common unit, which is approximately $598 million. 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. 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. Special meetings of AMGP shareholders and Antero Midstream unitholders will be held on March 8, 2019 to vote on the Simplification Agreement, the Merger and the other Transactions contemplated thereby, as applicable, and all AMGP shareholders and Antero Midstream unitholders of record as of the close of business on January 11, 2019, which is the record date for the special meetings, will be entitled to vote the AMGP common shares and Antero Midstream common units, respectively, owned by them on the record date. 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.

(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 consolidated financial statements as of December 31, 2018, include the accounts of the Partnership, Antero Midstream LLC (“Midstream Operating”), 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’s gathering and compression assets consist of high and low pressure gathering pipelines, compressor stations, and processing and fractionation plants that collect and process natural gas and NGLs from Antero Resources’ wells in West Virginia and Ohio. The Partnership’s water handling and treatment assets include two independent systems that deliver fresh water from sources including the Ohio River, local reservoirs as well as several regional waterways, an advanced wastewater treatment facility placed into service in 2018 and a related landfill used for the disposal of waste therefrom.

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 with MarkWest (the “Joint Venture”). See Note 14—Investments in Unconsolidated Affiliates.

The Partnership has been determined to be a variable interest entity and its financial statements are consolidated within the financial statements of Antero Resources (NYSE: AR), its primary beneficiary for financial reporting purposes.

On April 6, 2017, in connection with its initial public offering, Antero Resources Midstream Management LLC (“ARMM”) formed Antero Midstream Partners GP LLC (“AMP GP” or our “general partner”), a Delaware limited liability company, as a wholly owned subsidiary, and, on April 11, 2017, assigned to AMP GP the general partner interest in us. Concurrent with the assignment, AMP GP was admitted as the Partnership’s sole general partner and ARMM ceased to be our general partner.

On May 9, 2017, ARMM closed its initial public offering. In connection with the offering, ARMM was converted into a Delaware limited partnership, and changed its name to Antero Midstream GP LP (“AMGP”).

(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 partially owned 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, unitholders of the Partnership and holders of Series B Units 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 (the “Available Cash”) and Antero Resources received $3.00 in cash per common unit, which is approximately $598 million. 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. 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.

Special meetings of AMGP shareholders and Antero Midstream unitholders will be held on March 8, 2019 to vote on the Simplification Agreement, the Merger and the other Transactions contemplated thereby, as applicable, and all AMGP shareholders and Antero Midstream unitholders of record as of the close of business on January 11, 2019, which is the record date for the special meetings, will be entitled to vote the AMGP common shares and Antero Midstream common units, respectively, owned by them on the record date. 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.